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PCA9557DT - 8-Bit I2C I/O Expander | Texas Instruments
The Texas Instruments PCA9557DT is an 8-bit I2C and SMBus low-power I/O expander with reset and configuration registers, a 2.3 V to 5.5 V operating supply range, and a maximum bus clock frequency of 400 kHz. It is packaged as a 16-pin SOIC in the DT ordering configuration. The device expands one serial I2C interface into eight configurable parallel I/O lines, reducing microcontroller pin count and simplifying control of external digital functions. An I/O expander is an interface IC that translates serial commands from an I2C or SMBus controller into parallel digital inputs or outputs. The PCA9557 belongs to the broader embedded-interface hierarchy: I/O expander -> bus interface device -> interface IC -> semiconductor. It is useful when a system needs additional control or status lines without increasing the pin count of the main microcontroller, embedded processor, or programmable logic device. Key features include eight I/O ports, reset and configuration registers, support for both input and output operation, and low standby current consumption of 1 uA maximum according to the manufacturer data. The verified distributor listing identifies a 400 kHz I2C/SMBus interface and a 16-SOIC package. The PCA9557DT is intended for designs requiring a compact, serial-to-parallel expansion function, although exact pin names, electrical limits, and register behavior should be confirmed in the manufacturer datasheet before layout or firmware implementation. The device is used as an I2C target and communicates with a host controller through addressable registers. A host can configure port direction and then read or write port state, subject to the register definitions and electrical limits in the datasheet. Because I2C bus capacitance, pull-up resistance, address configuration, and peripheral power sequencing affect reliability, the device should be placed with short traces away from noisy switching stages. Typical applications include industrial control modules, sensor and actuator interfaces, programmable digital I/O, instrumentation, embedded control boards, and systems that need eight additional lines without expanding the host controller. The device can also complement a microcontroller such as an STM32H750VBT6TR when its direct GPIO budget is reserved for higher-speed or interrupt-sensitive functions. When selecting a replacement, verify the SOIC-16 footprint, pin mapping, I2C address behavior, reset requirements, output-drive limits, supply range, and register compatibility. PCA9557D is a relevant same-family ordering option, but package suffix and availability must be checked against the manufacturer’s ordering information. This page consolidates manufacturer and distributor sources, identifies the verified operating envelope, and provides practical design guidance for I2C bus design, decoupling, pull-ups, and lifecycle planning. It is intended to support component selection before the complete manufacturer datasheet is used for final electrical and production qualification.
PCA9557PW - 8-Bit I2C I/O Expander | NXP | 16-TSSOP
The NXP Semiconductors PCA9557PW is an 8-bit I2C/SMBus parallel input/output expander operating from 2.3 V to 5.5 V, with a 400 kHz bus rate and a 16-pin TSSOP package. It combines an 8-bit input port register, an 8-bit output port register, and an I2C/SMBus interface, allowing a microcontroller to control or monitor eight additional digital lines. The device also provides low current consumption and a high-impedance open-drain output on IO0. An I/O expander is an interface IC that extends the number of general-purpose inputs and outputs available to a host processor. The PCA9557 belongs to the parallel I/O expander class, connects to the I2C/SMBus hierarchy, and reduces the number of host-controller pins needed for buttons, indicators, relays, logic controls, and other digital peripherals. Its operating voltage range supports both 3.3 V and 5 V system contexts where the host and external signals use compatible logic levels. The verified product information identifies an 8-bit I/O expander, a 400 kHz I2C/SMBus interface, a 2.3 V to 5.5 V VCC range, and a 16-TSSOP package. The controller can configure the port direction and access the input and output registers through the serial bus. IO0 is specifically described as a high-impedance open-drain output, while the remaining port behavior and electrical limits should be confirmed in the manufacturer datasheet before final design release. Typical applications include low-pin-count embedded control, keypad and switch input consolidation, LED or indicator control, relay-interface logic, sensor-gate control, and general industrial or consumer equipment requiring eight remote digital lines. The I2C interface makes the PCA9557 especially useful when the host has limited spare pins but can provide an I2C bus. Firmware must define the device address, register behavior, port direction, pull-up requirements, and any open-drain load arrangement. For PCB implementation, place the device close to the connector or controlled signal group, route SDA and SCL as a short bus pair, and provide pull-up resistors only after checking the bus voltage, capacitance, speed, and number of devices. Do not assume that a mechanically similar 16-TSSOP part is pin-compatible: compare address, register map, pin functions, electrical limits, and I/O behavior against the manufacturer datasheet. This page consolidates the verified NXP product identity, package and bus information, practical application context, and the need for datasheet-level validation. It distinguishes confirmed facts from parameters that require a specific datasheet revision or device variant before being used in a production design.
PCA9557PWR - 8-Bit I2C I/O Expander | NXP | 16-TSSOP (Tape & Reel)
The NXP Semiconductors PCA9557PWR is an 8-bit I2C/SMBus parallel input/output expander operating from 2.3 V to 5.5 V, with a 400 kHz bus rate and a 16-pin TSSOP package. It combines an 8-bit input port register, an 8-bit output port register, and an I2C/SMBus interface, allowing a microcontroller to control or monitor eight additional digital lines. The device also provides low current consumption and a high-impedance open-drain output on IO0. An I/O expander is an interface IC that extends the number of general-purpose inputs and outputs available to a host processor. The PCA9557 belongs to the parallel I/O expander class, connects to the I2C/SMBus hierarchy, and reduces the number of host-controller pins needed for buttons, indicators, relays, logic controls, and other digital peripherals. Its operating voltage range supports both 3.3 V and 5 V system contexts where the host and external signals use compatible logic levels. The verified product information identifies an 8-bit I/O expander, a 400 kHz I2C/SMBus interface, a 2.3 V to 5.5 V VCC range, and a 16-TSSOP package. The controller can configure the port direction and access the input and output registers through the serial bus. IO0 is specifically described as a high-impedance open-drain output, while the remaining port behavior and electrical limits should be confirmed in the manufacturer datasheet before final design release. Typical applications include low-pin-count embedded control, keypad and switch input consolidation, LED or indicator control, relay-interface logic, sensor-gate control, and general industrial or consumer equipment requiring eight remote digital lines. The I2C interface makes the PCA9557 especially useful when the host has limited spare pins but can provide an I2C bus. Firmware must define the device address, register behavior, port direction, pull-up requirements, and any open-drain load arrangement. For PCB implementation, place the device close to the connector or controlled signal group, route SDA and SCL as a short bus pair, and provide pull-up resistors only after checking the bus voltage, capacitance, speed, and number of devices. Do not assume that a mechanically similar 16-TSSOP part is pin-compatible: compare address, register map, pin functions, electrical limits, and I/O behavior against the manufacturer datasheet. This page consolidates the verified NXP product identity, package and bus information, practical application context, and the need for datasheet-level validation. It distinguishes confirmed facts from parameters that require a specific datasheet revision or device variant before being used in a production design.
PCA9600D,118 - 1 MHz I2C-bus Buffer/ReDriver | NXP | 8-SO
The NXP PCA9600D,118 is a dual bidirectional bus buffer/ReDriver designed to isolate I²C-bus capacitance in point-to-point and multipoint applications up to 4000 pF. Housed in an 8-pin SO (SOIC-8) package, it operates at speeds up to at least 1 MHz and provides a non-latching, bidirectional logic interface between a standard I²C-bus and higher-capacitance or different-voltage bus segments. The high-drive side is compatible with the Fast-mode Plus (Fm+) specification, making the PCA9600 a higher-speed upgrade to the legacy P82B96. What is an I²C bus buffer? An I²C-bus buffer/ReDriver is a dedicated interface IC that sits between two bus segments to overcome the 400 pF capacitive limit of standard I²C. By isolating capacitance, a buffer allows engineers to extend bus length, add more nodes, use lower-cost cabling, or bridge between logic-voltage domains. Buffers/ReDrivers belong to the interface IC hierarchy: interface IC > bus buffer > I²C extender > signal conditioning, and are widely used in industrial backplanes, sensor arrays, and LED lighting chains where long cable runs would otherwise exceed the bus's RC budget. Key features of the PCA9600 include an operating supply voltage range from 2.5 V to 15 V on the low-voltage (standard I²C) side, with logic-level translation capability through the dual-rail architecture. The part is specified for -40 °C to +85 °C operation and offers high-impedance logic pins that prevent bus latching during plug-in or brown-out events. The device is bus-isolating rather than bus-repeating, so it cannot sink the I²C pull-up current from both sides simultaneously—designers must provide pull-ups on each side. Architecturally, the PCA9600 uses an internal pass-FET-style transmission gate with direction-sense amplifiers that detect which side is driving and steer current accordingly without requiring an external direction-control pin. The result is a drop-in, transparent bus extender that does not occupy an I²C address and does not appear as a node. Compared to discrete MOSFET plus pull-up solutions, the PCA9600 guarantees matched thresholds, controlled rise/fall times, and known hot-swap behavior across temperature. Common applications include industrial control backplanes, large-display LED driver chains, remote sensor arrays, and any system where the I²C master sits on one PCB and the slaves are several meters away on a cable or harness. The PCA9600D,118 ships on 13-inch tape and reel and is fully RoHS compliant, targeting high-reliability commercial and industrial designs. When designing with this part, pay close attention to the pull-up placement: each bus segment requires its own pull-up resistor sized for that segment's capacitance and the target rise time. Designers commonly pair the PCA9600 with 4.7 kΩ pull-ups on the master side and 1 kΩ to 2.2 kΩ pull-ups on the high-drive side to handle the larger bus capacitance.
PCA9601D,118 - 1MHz Fm+ I2C Bus Buffer SO-8 | NXP
The NXP PCA9601D,118 is a dual bidirectional I2C-bus buffer and repeater supporting operation to at least 1 MHz (Fast-mode Plus), with a wide 2.5 V to 15 V supply range, up to 4000 pF bus capacitance drive capability, and an 8-pin SO (SOIC-8) surface-mount package. An I2C-bus buffer is a specialized interface IC inserted between a controller-side I2C bus and one or more remote bus segments. Because the standard I2C bus is limited by total capacitance (typically 400 pF) and by the driving strength of the master device, long cables, backplanes, and daughter-card architectures quickly exceed these limits. A buffer isolates the capacitance of each bus segment, regenerates the signal edges, and allows each side to use a different supply voltage, making it a key building block within the interface IC and bus repeater/redriver family. Key features of the PCA9601 include bidirectional, non-latching signal transfer in both directions, compatibility with Fast-mode Plus (Fm+) drive requirements on the high-drive B-side, and voltage-domain separation so a 3.3 V controller bus can drive a 5 V, 12 V, or 15 V remote bus. According to NXP, the part isolates I2C-bus capacitance and permits point-to-point or multipoint buses of up to 4000 pF. Technically, the device implements an open-drain bidirectional buffer using NXP's proprietary level-shifting buffer architecture derived from the P82B96 family. It is a higher-speed version of the P82B96 and a higher-drive version of the PCA9600, meaning more Fm+ targets can hang on remote bus segments without timing violations. The 50 ns propagation delay class and 1 MHz capability keep rise/fall budgets intact at Fm+ speeds. Typical applications include long I2C runs in industrial backplanes, LED display panels, battery management systems, and remote daughter cards carrying many I2C targets where capacitance and drive strength would otherwise limit the bus. Design consideration: place the buffer close to the controller-side connector and size pull-up resistors separately for each bus segment, because the two sides have different drive strengths and voltage levels. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
PCA9601DPZ - 1MHz Dual I2C-Bus Buffer | NXP Semiconductors
The NXP Semiconductors PCA9601DPZ is a dual bidirectional I2C-bus buffer and repeater that isolates bus capacitance and drives loads up to 4000 pF, operating at speeds up to 1 MHz (Fast-mode Plus) in an 8-pin TSSOP surface-mount package. An I2C-bus buffer is a type of interface IC that sits between a standard I2C master/target segment and a long or heavily loaded bus segment. In the interface IC hierarchy (bus buffer -> signal repeater -> interface IC), its role is to regenerate signal edges and isolate capacitance, because the I2C specification limits total bus capacitance and rising-edge time. By splitting one bus into short segments, a buffer allows long cables, backplanes, and daughter-card interconnects that would otherwise violate I2C timing. Key features of the PCA9601 include 4000 pF bus drive capability, non-latching bidirectional logic that preserves the wired-AND I2C arbitration and clock-stretching behavior, and a high-drive side compatible with Fast-mode Plus (Fm+) specifications. It supports level translation between mixed-voltage bus segments (3.3V, 5V, and higher-voltage buffered sides), enabling communication between 3.3V and 5V systems while maintaining signal integrity and timing. The PCA9601 is architecturally a higher-speed version of the well-established P82B96 and a higher-drive version of the PCA9600. Its buffered, non-latching topology means the buffer never locks up during arbitration or repeated starts, a common failure mode of simpler repeater designs. The high drive strength allows many more Fast-mode Plus targets on remote daughter cards than an unbuffered bus could support. Typical applications include point-to-point and multipoint extension of I2C buses across cables and backplanes, isolating capacitance of remote daughter cards, mixed-voltage (3.3V/5V) system interfacing, and industrial or telecom equipment where many Fm+ targets must share a long bus. Devices such as the PCA8574, PCA9539, and PCA9538 I/O expanders are typical loads at the far end of a buffered segment. Design considerations: the PCA9601 specifies an operating temperature range of 0 C to 85 C, so it is intended for commercial and industrial indoor use rather than automotive-grade environments. Verify bus segment capacitance on both sides and follow the datasheet for pull-up sizing on the buffered side to meet Fm+ rise-time requirements. This page synthesizes distributor pricing context, drop-in family alternatives, and practical design notes not found in the manufacturer datasheet, with data verified as of 2026-10-20.
PCA9614DP,118 - 2-Ch Fm+ Differential I2C Bus Buffer | NXP
The NXP PCA9614DP,118 is a 2-channel multipoint Fast-mode Plus (Fm+) differential I2C-bus buffer with 400 kHz buffered operation, dual-supply differential signaling, and a 10-pin TSSOP (DP) surface-mount package. It extends a normal single-ended SMBus/I2C-bus across electrically noisy environments using a differential I2C (dI2C) physical layer that is fully transparent to the SMBus/I2C-bus protocol layer. An I2C-bus buffer and repeater is an interface IC that regenerates and drives bus signals, increasing fan-out, breaking capacitance limits, and lengthening bus reach. Within the interface IC hierarchy, buffer ICs sit between an I2C master/peripheral and the physical wire, and differential buffers such as this one add a robust physical layer without changing the protocol, so standard controllers require no firmware changes. Key features include two independent buffer channels supporting multipoint dI2C links over long cables, an EN pin that places the device in an idle state to stop traffic propagation, and an internal pull-up on EN that holds the device enabled by default. The differential transmission rejects common-mode noise, making the link tolerant of ground potential differences between boards. Technically, the PCA9614 converts the single-ended SDA/SCL levels into a differential pair per channel at the buffer output side, and converts back to single-ended at the receiving end when paired with another differential buffer. Because the dI2C layer is protocol-transparent, arbitration, clock stretching, and Fm+ 400 kHz (1 MHz capable) timing behave exactly as on a standard bus, while cable capacitance and noise immunity requirements are decoupled from the bus segment. Typical applications include industrial automation bus extension, rack and backplane inter-board communication in servers, battery management systems in electrically noisy traction environments, and long-run I2C links between enclosures or display modules. A key design consideration is power sequencing of the dual supplies (VDD(A) on the single-ended side and VDD(B)/VL on the differential side); both must remain within the datasheet recommended operating conditions and EN should be held low during startup to prevent glitching. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, with freshness data as of 2026-10-20.
PCA9615DPZ - 2-Ch I2C Fast-Mode Plus Diff Buffer | NXP
The NXP Semiconductors PCA9615DPZ is a 2-channel multipoint Fast-mode Plus differential I2C-bus buffer with hot-swap logic, operating up to 1 MHz, housed in a 10-pin TSSOP (SOT552-1) package. It supports standard I2C, Fast-mode, and SMBus compatibility, with single-ended I2C on the card side up to 540 pF and differential I2C on the cable side supporting multi-drop bus up to 3 meters. The device uses an external DCEN pin to enable/disable the differential driver and operates from dual supplies, typically VDD(A) on the single-ended side and VDD(B) on the differential side. A signal buffer, repeater, or redriver is an active interface IC placed in-line on a bus to restore signal integrity when the load capacitance or physical distance exceeds the limit of the bus specification. In the I2C hierarchy, this part is a specialized bus extender/repeater that converts a single-ended SDA/SCL pair into a differential pair for transmission over twisted-pair or shielded cable, then converts back at the far end. This is essential in industrial control, automotive sensor backbones, and large backplane systems where standard I2C's capacitive limit (~400 pF) is insufficient. Key features of the PCA9615DPZ include differential transmission across a cable up to 3 meters at Fast-mode Plus speeds, hot-swap logic that allows the card to be inserted into a live backplane without disturbing the bus, wide supply range (2.7 V to 5.5 V on VDD(A) and 3.0 V to 5.5 V on VDD(B)), and AEC-Q100 qualification for automotive applications. The hot-swap circuitry prevents inrush current and bus glitches during card insertion. The differential pair uses low-voltage signaling to reduce EMI compared to single-ended transmission. Typical applications include industrial I2C backplane extension, automotive sensor networks, hot-swappable I/O cards, multi-drop I2C sensor clusters, and remote sensor/PCI configuration. The device is particularly valuable where cables must span meters between cards, sensors, or backplane slots, and where live insertion is needed without disrupting the system bus. When designing with this part, ensure both VDD rails are decoupled with 100 nF ceramic capacitors placed within 5 mm of the supply pins. Verify the differential pair routing on the cable side is twisted-pair or shielded to meet EMI requirements; the part itself does not include cable termination resistors, so external 100 ohm differential termination may be required at the far end for very long runs.
PCA9616PW - 3-Channel Differential I2C Bus Buffer | NXP
The NXP Semiconductors PCA9616PW is a dual-supply, 3-channel multipoint Fast-mode Plus (Fm+) differential I2C-bus buffer with hot-swap logic, packaged in a 16-pin TSSOP (PW) surface-mount package. It buffers the single-ended SMBus/I2C-bus up to 1 MHz and converts it to a differential I2C (dI2C) bus that reliably extends communication through electrically noisy environments over cable runs of at least 3 meters, or longer at reduced clock speeds. A differential I2C-bus buffer, sometimes called a bus repeater or redriver, is an interface IC that belongs to the signal buffer family within the broader hierarchy of interface integrated circuits. Where a plain I2C bus uses open-drain single-ended lines vulnerable to ground bounce and common-mode noise, a dI2C buffer translates the bus into a differential current-mode signaling scheme, dramatically improving common-mode noise immunity while remaining fully compatible with existing Standard-mode, Fast-mode, and Fast-mode Plus I2C and SMBus devices. Key features of the PCA9616PW include its 3-channel multipoint architecture, which supports a dI2C bus shared by multiple nodes for multipoint topologies; its dual-supply design isolating the single-ended side from the differential side; support for Fast-mode Plus operation at 1 MHz; and integrated hot-swap logic that allows a card or module to be inserted into or removed from a live backplane without corrupting bus transactions. Signal direction is fully automatic, requiring no external direction-control signal. Technically, the device pairs each single-ended SDA and SCL line with differential transmit/receive pairs on the cable side, using current-mode differential drivers and receivers with high common-mode noise rejection. Because it is a multipoint buffer, several PCA9616 devices can share one differential cable, enabling distributed systems such as rack-mounted cards, industrial backplanes, and remote sensor clusters. NXP documents cable extension of at least 3 m, with longer runs achievable at lower bus speeds. Typical applications include industrial backplane I2C distribution, telecom and server shelf management, multipoint sensor networks in electrically noisy factory environments, and hot-pluggable module bus extension. The hot-swap logic makes it especially suitable for field-replaceable cards. Design consideration: plan the differential bus topology to respect multipoint stub-length limits, and verify supply sequencing on both the single-ended and differential rails against the manufacturer datasheet to guarantee correct hot-swap behavior. This page synthesizes distributor pricing, drop-in replacement analysis, and practical design notes not found in the manufacturer datasheet.
PCA9670BS,118 - 8-bit Fm+ I2C I/O Expander w/ Reset, HVQFN-16
The NXP PCA9670BS,118 is a remote 8-bit I/O expander for Fast-mode Plus (Fm+) I2C-bus with reset, packaged in a 16-pin HVQFN (3x3 mm) with exposed thermal pad. The device provides general-purpose remote I/O expansion for most microcontroller families via the two-line bidirectional I2C-bus, and supports a clock frequency of up to 1 MHz. Operating supply range is 2.3 V to 5.5 V, allowing use with 3.3 V and 5 V logic rails. The integrated RESET input and quasi-bidirectional I/O structure simplify firmware and PCB design when adding buttons, LEDs, keypads, or sensor interfaces to an embedded system. An I/O expander (also called a port expander or GPIO expander) is a category of interface IC that multiplies the limited GPIO pins of a microcontroller through a serial bus. In the taxonomy I/O expander -> interface IC -> integrated circuit -> semiconductor, the PCA9670BS sits in the parallel-bus-expansion tier and uses I2C as the transport. By attaching the part to SCL/SDA, designers gain eight additional quasi-bidirectional I/O pins addressed through a 7-bit slave address. Three hardware address pins (A0, A1, A2) allow up to 64 PCA9670 devices on the same bus, supporting up to 512 I/Os (for example 512 LEDs) without external bus buffers. Key features include 1 MHz Fm+ bus support (compared with 400 kHz for the classic PCF8574), a hardware RESET pin that reverts all ports to inputs, low standby current, and 5 V tolerant I/O structure that tolerates bus pulls above VDD. The HVQFN-16 (3x3) package provides a low 0.5 mm profile with an exposed die attach paddle for improved thermal performance, making it suitable for compact industrial, consumer, and IoT designs. NXP specifies ESD protection exceeding 2 kV HBM on the I/O pins, and the part is qualified to the industrial -40 C to +85 C operating range. The PCA9670 architecture uses an I2C state machine with interrupt logic for input-change notifications and a separate RESET input that asynchronously clears internal state. Internally each I/O pin is a quasi-bidirectional structure - capable of sinking current to drive LEDs directly while also serving as an input when written high. This dual-mode behavior differs from push-pull GPIO and is important when migrating designs from the older PCF8574/PCF8575 family. Typical applications include keypad and button-matrix scanning in white goods and access control, LED driving and chase patterns in industrial control panels, sensor multiplexing on Raspberry-Pi-class SBCs where the host lacks enough native GPIO, and general-purpose I/O expansion in PLC and HVAC controllers. The wide 2.3-5.5 V supply range plus 1 MHz Fm+ bus speed also suits battery-powered IoT nodes that need to minimize I2C transaction time. When designing with this part, place 100 nF decoupling close to VDD, use external pull-ups on SDA/SCL sized for the bus capacitance (typically 4.7 kohm at 1 MHz), and avoid leaving the RESET pin floating - tie it to VDD through a 10 kohm resistor or drive it from the host MCU. The I/O sink capability must be checked against LED forward current; sourcing current is limited and the quasi-bidirectional behavior must be considered when interfacing to logic-level peripherals. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the NXP datasheet.
PCA9675PW,118 - 16-bit Fm+ I2C I/O Expander | NXP | TSSOP-24
The NXP PCA9675PW,118 is a 16-bit remote I/O expander for the Fast-mode Plus (Fm+) I²C-bus, supplied in a 24-pin TSSOP (PW) package and shipped on 13-inch tape and reel. It operates from a supply voltage of 2.3 V to 5.5 V, clocks the I²C interface at up to 1 MHz, and exposes 16 quasi-bidirectional I/O lines that can source/sink up to 30 mA per pin with a 100 mA total package limit. An I/O expander (also called a port expander or GPIO expander) is a category of interface IC that increases the number of general-purpose I/O pins available to a host microcontroller over a serial bus such as I²C. In the system hierarchy it sits between the MCU and the discrete digital loads (LEDs, keypads, sensors, relay coils), translating compact I²C transactions into parallel pin-level updates. The PCA9675 belongs to NXP's Fm+ family, which is optimized for high-speed serial I/O expansion in noisy or long-trace industrial backplanes. Key features include three hardware address pins (A0/A1/A2) supporting up to eight PCA9675 devices on the same bus, an active-low interrupt output (INT) that asserts when any input changes and releases on the next I²C read, an active-low reset input with internal power-on reset, and per-pin latch-up current exceeding the 100 mA JESD78 limit. The device is a drop-in upgrade for the legacy PCF8575, lifting bus speed from 400 kHz to 1 MHz and raising sink current capability. Typical applications include PWM dimming of LED arrays (each pin can be modulated at >1 MHz bus rates), keypad and switch-matrix scanning, fan-speed and relay control in industrial PLCs, and general-purpose I/O expansion for low-pin-count MCUs in white goods, HVAC, and IoT edge nodes. Designers value the wide 2.3–5.5 V supply range because it allows direct interface to both 3.3 V and 5 V microcontrollers without level shifters. When designing with this device, place 100 nF decoupling on VDD as close as possible to the pin and pull SDA/SCL high with 4.7 kΩ resistors for standard 400 kHz operation or 1 kΩ for the full 1 MHz Fm+ rate. Note that quasi-bidirectional outputs require no external pull-up on the load side because an internal weak pull-up is enabled after each read cycle.
PCA9703PW/Q900 - 16-bit SPI GPI, 18V Tolerant | NXP
The NXP Semiconductors PCA9703PW/Q900,118 is an 18 V tolerant, 16-bit SPI General Purpose Input (GPI) shift register with maskable interrupt output, housed in a 24-pin TSSOP (PW) package rated -40 C to +125 C. It operates as an SPI slave at up to 5 MHz and monitors 16 switch or logic inputs with 18 V input tolerance, making it a low-power solution for high-voltage switch status monitoring in automotive and industrial systems. A GPI (General Purpose Input) shift register is a type of input-only I/O expander within the broader hierarchy of interface ICs -> I/O expanders -> parallel-in serial-out shift registers. Unlike I2C GPIO expanders, SPI GPI shift registers stream input states to a microcontroller as a serial bit field, which minimizes pin count on the host MCU and gives deterministic, fast read-back of many switch contacts. Key features include 16 input-only channels tolerant to 18 V regardless of the device supply, a maskable INT output that flags any change of input state, a 3 V input switching threshold for robust noise immunity, and SPI compatibility up to 5 MHz. The Q900 suffix and /Q900,118 ordering code identify the automotive AEC-Q100 compliant variant with extended -40 C to +125 C operation; NXP states that PCA9703PW/Q900 is AEC-Q100 compliant and PPAP documentation is available via i2c.support@nxp.com. Technically, the PCA9703 samples its 16 GPI inputs into an internal shift register and shifts data out on MISO under host control of CS and SPI clock. Any input change (open, closed, or 12 V/24 V level via divider) triggers the interrupt output, which can be masked to prevent nuisance CPU wake-ups. The low-power CMOS process keeps static consumption minimal, which is critical for always-on battery-backed switch monitoring. Typical applications include automotive switch monitoring (door, window, seat, and steering-column switches), industrial control panels and limit-switch monitoring, and 12 V/24 V system status sensing where contacts ride on battery-level rails the chip inputs directly tolerate. A key design consideration is input threshold scaling: although inputs tolerate 18 V, the 3 V threshold means designers must confirm logic levels and switch pull-up arrangements so that a valid LOW is below threshold and a valid HIGH is safely above it across temperature. This page synthesizes distributor pricing, lifecycle status, drop-in alternative analysis, and practical design notes not found in the manufacturer datasheet alone.
PCA9703PW/Q900,118 - 16-Bit SPI GPI 18V Tolerant | NXP
The NXP Semiconductors PCA9703PW/Q900,118 is an 18 V tolerant SPI 16-bit General Purpose Input (GPI) shift register with maskable interrupt output, supplied in a 24-pin TSSOP package rated for -40 C to +125 C automotive operation with a 4.5 V to 5.5 V supply and a 5 MHz SPI clock. A general purpose input shift register is a specialized interface IC that converts parallel logic levels from switches or sensors into a serial data stream. In the system hierarchy it sits between raw switch inputs and a microcontroller: instead of dedicating 16 MCU pins to switch monitoring, a single SPI port reads all 16 inputs as a serial word, reducing pin count, wiring harness complexity, and cost in distributed control systems. Key features include 18 V tolerance on all GPI pins, allowing direct connection to automotive battery-nominal rails without level shifting; a maskable interrupt output (INT) with an INT_EN pin that disables the inputs and interrupt to minimize battery drain in cyclically powered systems; and an SDIN pin with pull-down that supports daisy-chaining multiple devices on a single SPI bus for 32, 48, or more inputs. Architecturally, the PCA9703 uses a shift register with a dedicated output enable controlled by CS. The 3 V logic thresholds on the serial interface ensure compatibility with both 3.3 V and 5 V controllers. Switch status is captured in the parallel input register and shifted out MSB-first on SCLK edges, with the interrupt flag readable on the first serial byte so the MCU can branch quickly on any input change. Typical applications include automotive switch monitoring for door, seat, and steering-column controls, body control modules and keypads, and industrial panels requiring isolated or battery-tolerant digital inputs. The 18 V tolerance is the decisive parameter wherever switches are wired to unregulated supply rails. A key design consideration: the GPI inputs require external pull-up or pull-down resistors to the switched rail; the INT_EN pin should be driven low during system sleep to eliminate quiescent current drawn through those resistors. This page synthesizes distributor pricing, drop-in alternative analysis, design notes, and application guidance not found in the manufacturer datasheet, making it a one-stop engineering reference for the PCA9703PW/Q900,118.
PCA9704PW/Q900 - 8-bit SPI GPI 18V Tolerant | NXP
The NXP Semiconductors PCA9704PW/Q900 is an 8-bit, 18 V tolerant SPI General Purpose Input (GPI) shift register with maskable interrupt, AEC-Q100 qualified for automotive applications, housed in a 16-pin TSSOP (PW) package. It monitors the status of switch inputs and reads them out over a standard SPI interface running at up to 5 MHz. A general-purpose input expander is an interface IC that offloads switch or status-signal monitoring from a microcontroller. In the signal-chain hierarchy, the PCA9704 sits between discrete switch contacts and an MCU's SPI peripheral: GPIO expander -> interface IC -> mixed-signal logic device. Input expanders are used when an MCU lacks sufficient input pins or when switch signals sit at voltages higher than the MCU supply, as is common in automotive 12 V and 24 V electrical systems. Key features include eight input channels each tolerant to 18 V, allowing direct connection to battery-referenced switch contacts without external level shifting or clamping networks. The SPI interface supports read-out at up to 5 MHz, and a maskable interrupt output (INT) alerts the host controller only when inputs change, enabling low-power polled or event-driven system architectures. Technically, the PCA9704 is implemented as a parallel-in serial-out shift register with input latching. When the host asserts the chip-select, the current input state is latched and shifted out on the SPI data line; devices can be cascaded to expand beyond eight inputs on a single SPI bus. The /Q900 suffix denotes NXP's automotive product-line extension with AEC-Q100 compliance and PPAP support, distinguishing it from the commercial-grade PCA9704PW. Typical applications include automotive switch monitoring (door, seat, and key contacts), industrial control-panel status readback, and system diagnostics where battery-level fault or presence signals must be safely captured by a low-voltage controller. Design consideration: although the 18 V tolerance removes the need for input dividers, verify worst-case battery load-dump transients in automotive systems and confirm that the interrupt mask register is initialized before enabling INT to avoid spurious wake-ups at power-up. This page synthesizes distributor data, automotive-grade alternative options, and practical SPI integration notes not found in the manufacturer datasheet, with pricing verified as of 2026-10-19.
PCAL6408AHK - 8-Bit I2C I/O Expander, XQFN-16 | NXP
The NXP Semiconductors PCAL6408AHK is a low-voltage translating, 8-bit general-purpose I/O expander with interrupt output, reset, and Agile I/O configuration registers, interfacing to a host microcontroller via I2C-bus/SMBus at up to 400 kHz in a 16-pin XQFN (1.8 x 2.6 mm) package. An I/O expander is a peripheral IC that adds extra general-purpose input/output pins to a microcontroller or embedded processor over a serial bus such as I2C or SMBus. In the system hierarchy, it sits within the interface IC family, under mixed-signal peripheral devices, and complements microcontrollers whose native GPIO count is exhausted. Expanders offload GPIO expansion while consuming only two bus wires (SDA, SCL), conserving processor pins and board routing. Key features include a wide supply range of 1.65 V to 5.5 V, dual power rails for true voltage level translation between logic domains, programmable output drive strength, and latchable inputs. The interrupt output and active-low reset provide robust event-driven and fault-recovery behavior in multi-slave I2C systems. The Agile I/O feature set - configurable output drive, input latch, and pull-up/pull-down enable - allows system designers to tune signal integrity and power per pin, which is significant in mixed-voltage designs where a 1.8 V MCU must safely drive 3.3 V or 5 V peripherals. Open-drain and push-pull operating modes over I2C/SMBus at 400 kHz provide flexible bus integration. Typical applications include GPIO expansion in portable and battery-powered devices, level translation between low-voltage processors and legacy 5 V peripherals, sensor and keypad scanning, LED control, and backplane status monitoring in industrial systems. Design consideration: because the XQFN-16 package measures only 1.8 x 2.6 mm, the exposed pad must be soldered to a grounded PCB land pattern for reliable thermal and mechanical performance; verify land-pattern tolerances before assembly. This page synthesizes distributor pricing context, drop-in alternatives, practical design notes, and AEO-optimized FAQs not found in the NXP datasheet.
PCF85176T/1 - 40x4 LCD Segment Driver I2C TSSOP-56 | NXP
The NXP Semiconductors PCF85176T/1 is a universal LCD segment driver with 40 segments and 4 backplanes, packaged in a 56-pin TSSOP (TSSOP-56). It interfaces to almost any Liquid Crystal Display (LCD) with low multiplex rates via an I2C-bus and generates the drive signals required for static or multiplexed LCDs up to 4x40. The device supports a frame frequency of 82 Hz and is widely used where cascadable LCD expansion is needed. A segment driver (LCD driver) is a peripheral device that translates digital commands from a microcontroller into the multi-level AC waveforms required to drive a passive-matrix liquid crystal display. LCD segment drivers sit in the display driver hierarchy above simple character LCD modules, providing designers with a low-pin-count way to control custom glass through bias generation, backplane sequencing, and segment latching. The PCF85176T/1 combines on-chip bias generation with a serial I2C interface so an MCU only needs two I/O lines to address 160 individual pixel segments. Key features include 40 segment outputs plus 4 backplane outputs (160 pixel capability), integrated charge-pump-based LCD bias voltage generator, selectable bias modes for static, 2-way, 3-way, and 4-way multiplexing, an I2C-bus interface with hardware-selectable slave addresses for cascading, on-chip oscillator requiring no external components, and a wide logic supply range compatible with 3.3 V and 5 V microcontrollers. The CMOS process and TSSOP-56 footprint keep the part economical for mid-volume industrial and consumer LCD designs. The architecture consists of an I2C slave controller, a display RAM of 80 bits (40 segments x 2 pages), a programmable frame frequency generator, and a segment/backplane driver block tolerant of liquid crystal threshold voltages typically between 3 V and 9 V. The integrated VLCD generator eliminates the need for an external DC-DC converter in many designs, reducing BOM cost and PCB area. Typical applications include point-of-sale (POS) terminals, industrial control panels with character or numeric LCDs, white-goods user interfaces such as washing machines and microwave ovens, automotive instrument cluster sub-displays, medical instrument readouts, and metering equipment (water/gas/electricity meters). Cascading multiple PCF85176T/1 devices enables larger glass panels, supporting display sizes up to 320 segments in a chain. When designing with this part, use the on-chip bias generator to produce VLCD rather than an external rail, and reserve one I2C address bit per cascaded chip. Designers should also enable the internal oscillator unless precise frame frequency synchronization is required by the application.
PCF8562TT/2 - 4x32 I2C LCD Segment Driver | NXP | TSSOP-48
The NXP PCF8562TT/2 is a universal LCD segment driver with 4 backplanes and 32 segments, controlled via the two-line bidirectional I2C-bus, housed in a 48-pin TSSOP (SOT362-1) package. It supports supply voltages of 2.5V, 3.3V, and 5V, a typical frame frequency of 64 Hz, and operating temperatures from -40C to +85C. The CMOS device drives static, 2-way, 3-way, or 4-way multiplexed LCDs with selectable static, 1/2, or 1/3 bias configuration. An LCD segment driver is an integrated circuit that generates the AC voltage waveforms required to drive individual segments of a liquid-crystal display. It sits hierarchically between the microcontroller (which decides what to display) and the LCD glass (which physically renders pixels). The PCF8562 belongs to the LCD driver family, which is a subcategory of display driver ICs, itself part of the broader power management and interface semiconductor landscape. Because it uses I2C and runs from a single low-voltage rail, it is a common choice in battery-powered and embedded designs. Key features include selectable backplane drive configuration (static, 2, 3, or 4 backplane multiplexing), selectable display bias configuration (static, 1/2, or 1/3), and a 64 Hz typical frame frequency that minimizes flicker for direct-driven LCDs. The device integrates charge-pump-based bias generation and can drive up to 128 segments in 4-mux mode (4 backplanes x 32 segments). Automotive-grade variants such as PCF8562TT/S400/2 carry AEC-Q100 compliance, making the family suitable for dashboard clusters and instrument panels. From a technical depth perspective, the PCF8562 uses CMOS technology to minimize quiescent current, supports cascadable I2C clock stretching, and includes an internal oscillator with external resistor adjustment. The architecture separates the I2C slave logic (pins SDA, SCL, SA0) from the high-voltage LCD driver outputs (BP0-BP3, S0-S31), allowing the digital core to operate at logic levels while the segment outputs swing to VLCD. Designers typically pair the PCF8562 with a host MCU such as the LPC family or general-purpose microcontrollers using only two GPIO pins for the entire interface. Typical applications include metering displays (electricity, water, gas meters), white goods front panels, point-of-sale terminals, automotive instrument clusters (with the /S400/2 variant), medical device readouts, and any low-multiplex-rate character or graphic LCD up to 32 segments per chip. Two or more PCF8562 devices can share a single I2C bus by using different SA0 slave-address straps. The 48-pin TSSOP footprint makes it compatible with hand-solderable prototypes and high-density production boards alike. When designing with the PCF8562, ensure VLCD is properly bypassed with a 100 nF ceramic capacitor and that BP0-BP3 traces are kept short to reduce display ghosting. Designers should also verify the slave address selection via the SA0 pin to avoid bus conflicts when cascading multiple drivers. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
PCF8574AN - 8-Bit I/O Expander | Texas Instruments | DIP
The Texas Instruments PCF8574AN is an 8-bit remote I/O expander intended for digital input and output expansion in embedded systems. The device communicates with a host controller through a two-wire serial interface and provides eight separately addressable I/O lines. It is supplied in a 16-pin dual in-line package, with the AN order suffix identifying the packaged variant. This addressable I/O architecture places the PCF8574AN in the interface IC hierarchy: serial interface controller, I/O expander, embedded-system interface, and semiconductor. A remote I/O expander reduces the number of general-purpose I/O pins required on a microcontroller, programmable logic controller, or other embedded controller. Eight digital lines can be distributed across a remote circuit board, allowing buttons, indicators, logic inputs, or other digital signals to connect to a shared two-wire bus. The PCF8574AN therefore reduces package size and routing complexity when a design requires more digital interface lines than the host controller provides directly. The verified dataset supplied for this product contains no manufacturer-document specifications or distributor records. Consequently, operating voltage, address range, output-drive capability, clock frequency, logic thresholds, quiescent current, and environmental ratings are not asserted on this page. These parameters must be confirmed from the applicable Texas Instruments manufacturer datasheet before the IC is used in a new schematic, PCB layout, firmware configuration, or safety- and reliability-critical design. The PCF8574AN is typically associated with 5 V and 3.3 V embedded systems, but the actual supported supply range and interface levels are deliberately left unspecified here because no verified manufacturer data was provided. Logic-level compatibility must be evaluated using the authoritative input thresholds, output leakage, and output-driver specifications rather than nominal rail voltage alone. Typical design candidates include general-purpose microcontroller I/O expansion, programmable controller input modules, front-panel button and indicator handling, and simple industrial control boards. An I2C or other two-wire host bus may be shared by multiple expanders only after address allocation, electrical loading, pull-up requirements, and bus-speed limits have been verified. The primary layout concern is the two-wire bus. Place pull-up resistors and decoupling capacitors close to the appropriate bus endpoints, keep the clock and data traces short, and confirm that every connected device can tolerate the selected voltage and clock rate. Firmware must also establish the device address and configure each line as input or output before external hardware is energized. This page combines an authenticity-first specification record with procurement, replacement, selection, and design-intent guidance. Because the retrieved distributor and cross-reference searches returned no records, market pricing, lifecycle availability, exact pin naming, and additional drop-in alternatives remain explicitly unverified rather than being inferred from similar devices.
PCF8574AT/3,518 - 8-bit I2C I/O Expander | NXP SOIC-16
The NXP PCF8574AT/3,518 is an 8-bit I/O expander with quasi-bidirectional I/O pins, an I2C-bus interface operating up to 100 kHz, and an open-drain interrupt output, housed in a 16-pin SO (SOIC-16, MS-013/SOT-162-1) plastic package. It operates from 2.5 V to 6 V supply, supports three hardware address pins (A0-A2), and provides a different fixed I2C address base than the PCF8574 (0x3F for the PCF8574A family vs 0x20 for the PCF8574A base, allowing up to eight of each on the same bus). The CMOS silicon-gate design draws low quiescent current (typ. 40 uA) and supports a maximum of 16 PCF8574/PCF8574A devices on one shared I2C-bus, expanding up to 128 I/Os. An I/O expander is a class of digital peripheral IC that extends the limited GPIO count of a host microcontroller through a serial bus, allowing additional inputs, outputs, keypads, LED indicators, and signal-conditioning lines without increasing pin count on the MCU. Within the hierarchy of interface ICs (also called bus expanders or GPIO extenders), the PCF8574AT belongs to the I2C-bus parallel-port family, positioned between simple shift-register expanders (which lack interrupt capability) and full SPI/I2C port-mapped devices. This category sits under digital logic and interface ICs in broader semiconductor taxonomy, supporting both consumer and industrial designs where MCU pin count is constrained. Key features include quasi-bidirectional I/O that can directly drive LEDs without external pull-ups (sinking capability of up to 25 mA per pin, max 100 mA total), an active-low interrupt output (INT) that signals the host when any input state changes, and 400 kHz Fast-mode I2C capability on the PCF8574A/PCF8574AT family variants. The device integrates a noise filter on the SCL/SDA lines and supports clock stretching as a slave device. The PCF8574AT uses a CMOS silicon-gate architecture with latched output registers and input latches on every I/O pin. The quasi-bidirectional design uses a weak pull-up (typically 100 uA current source) to drive outputs high; pulling low requires the pin to actively sink current. This architecture eliminates the need for external pull-up resistors on outputs while maintaining low standby current. Typical applications include driving LED arrays, LCD segment interfaces, keypad matrix scanning, fan-speed monitoring, relay control boards, and general-purpose I2C slave peripheral expansion in industrial control, consumer electronics, and embedded systems. Engineers commonly pair the PCF8574AT with low-power MCUs (such as the LPC1100 or PIC16F families) to add 8-bit digital I/O over only two signal wires. When designing with this part, note that the quasi-bidirectional I/O pins have an asymmetric drive capability - they source weakly (100 uA) but sink strongly (25 mA per pin). This makes them ideal for LED-driving (sink mode) but less suitable as push-pull signal drivers. Always respect the absolute maximum of 100 mA total current through the VDD/GND pins to avoid latch-up. This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet alone, including cross-references for the very similar PCF8574T/3 (different I2C address range).
PCF8574DW - 8-Bit 100kHz I2C I/O Expander | Texas Instruments
Texas Instruments PCF8574DW is an 8-bit I2C I/O expander with a 100 kHz bus, eight quasi-bidirectional ports, and an interrupt output, supplied in a 16-SOIC package. According to the manufacturer product page, it supports 2.5 V to 5.5 V operation, while the manufacturer datasheet search result describes 2.5 V to 6 V VCC operation. The device adds eight parallel digital lines to a host microcontroller without consuming eight dedicated GPIO pins. An I/O expander is an interface IC that translates serial I2C commands into parallel digital inputs or outputs. The PCF8574 belongs to the parallel-port expansion and I2C interface hierarchy. It uses two bus lines, SCL and SDA, to receive configuration and port-state data from a microcontroller, then presents P0 through P7 as individually controlled digital ports. Its interrupt output allows a host to react when an input condition changes without continuously polling the bus. The principal features include eight I/O ports, a maximum I2C clock frequency of 100 kHz, a 2.5 V to 6 V VCC operating range stated in the datasheet, and low standby-current consumption with a listed maximum standby current of 10 µA. The open-drain interrupt output is compatible with common microcontroller interrupt inputs. The 16-SOIC package is a surface-mount SOIC-16 footprint, and the DWR tape-and-reel ordering code must not be confused with the DW tube ordering code. The quasi-bidirectional port architecture makes the PCF8574 useful for simple control and status signals. A port can be written as an output or sampled as an input, but the electrical behavior and pull-up implementation require care when driving external loads. The interrupt pin provides an event-oriented alternative to periodic reads when one or more input lines change state. Firmware must also verify the device address and bus pull-up arrangement when multiple expanders share the same two-wire bus. Typical applications include keypad and control-panel scanning, relay or solenoid control, LED indication, sensor and switch input aggregation, industrial control modules, and general embedded systems where a microcontroller has too few GPIO pins. The expander is particularly useful when the required signals are simple logic levels and the bus is already present. It is less suitable when high-speed edge-sensitive inputs, high-current output drive, or strong isolation requirements are present. Designers should verify pull-up resistors on SDA and SCL, ensure that all connected devices use compatible voltage levels, and account for total bus capacitance. Port pins intended as inputs should not be forced into incompatible logic states, while output loads should remain within verified current and voltage limits. This page combines the supplied manufacturer and distributor data with practical design guidance, comparison parameters, and sourcing information.
PCF8574DWR - 8-Bit 100kHz I2C I/O Expander | Texas Instruments (Tape & Reel)
Texas Instruments PCF8574DWR is an 8-bit I2C I/O expander with a 100 kHz bus, eight quasi-bidirectional ports, and an interrupt output, supplied in a 16-SOIC package. According to the manufacturer product page, it supports 2.5 V to 5.5 V operation, while the manufacturer datasheet search result describes 2.5 V to 6 V VCC operation. The device adds eight parallel digital lines to a host microcontroller without consuming eight dedicated GPIO pins. An I/O expander is an interface IC that translates serial I2C commands into parallel digital inputs or outputs. The PCF8574 belongs to the parallel-port expansion and I2C interface hierarchy. It uses two bus lines, SCL and SDA, to receive configuration and port-state data from a microcontroller, then presents P0 through P7 as individually controlled digital ports. Its interrupt output allows a host to react when an input condition changes without continuously polling the bus. The principal features include eight I/O ports, a maximum I2C clock frequency of 100 kHz, a 2.5 V to 6 V VCC operating range stated in the datasheet, and low standby-current consumption with a listed maximum standby current of 10 µA. The open-drain interrupt output is compatible with common microcontroller interrupt inputs. The 16-SOIC package is a surface-mount SOIC-16 footprint, and the DWR tape-and-reel ordering code must not be confused with the DW tube ordering code. The quasi-bidirectional port architecture makes the PCF8574 useful for simple control and status signals. A port can be written as an output or sampled as an input, but the electrical behavior and pull-up implementation require care when driving external loads. The interrupt pin provides an event-oriented alternative to periodic reads when one or more input lines change state. Firmware must also verify the device address and bus pull-up arrangement when multiple expanders share the same two-wire bus. Typical applications include keypad and control-panel scanning, relay or solenoid control, LED indication, sensor and switch input aggregation, industrial control modules, and general embedded systems where a microcontroller has too few GPIO pins. The expander is particularly useful when the required signals are simple logic levels and the bus is already present. It is less suitable when high-speed edge-sensitive inputs, high-current output drive, or strong isolation requirements are present. Designers should verify pull-up resistors on SDA and SCL, ensure that all connected devices use compatible voltage levels, and account for total bus capacitance. Port pins intended as inputs should not be forced into incompatible logic states, while output loads should remain within verified current and voltage limits. This page combines the supplied manufacturer and distributor data with practical design guidance, comparison parameters, and sourcing information.
PCF8574N - 8-Bit 100kHz I2C I/O Expander | Texas Instruments
The Texas Instruments PCF8574N is an 8-bit bidirectional I/O expander for the I2C bus, operating from 2.5V to 6V with a 100kHz interface and housed in a 16-pin PDIP package. It adds eight quasi-bidirectional remote I/O lines to a host microcontroller while providing open-drain interrupt signaling. The device is designed for general-purpose expansion across embedded control, communications, and embedded accessory designs. What is an I2C I/O expander? An I/O expander is an interface IC that translates serial bus commands into parallel digital signals. The PCF8574N belongs to the I/O-expander class, which sits within interface ICs and broader semiconductor systems. It helps a controller with too few GPIO pins operate additional buttons, indicators, relays, or other digital peripherals while preserving a shared SDA and SCL bus. Key features include eight I/O ports, 100kHz I2C operation, a 2.5V to 6V supply range, and an interrupt output. Its quasi-bidirectional ports can be configured as inputs or outputs, while power-on behavior and external pull-up requirements must be considered in the system design. The verified distributor listing identifies the PCF8574N as an 8-bit, 100kHz I/O expander in a PDIP package. The device uses the PCF8574 family architecture in which the host communicates over the two-wire I2C bus and reads or writes the remote port state. Because the ports are quasi-bidirectional rather than independently powered high-impedance inputs and outputs, firmware and external circuitry should avoid contention scenarios. The interrupt line provides a hardware indication that input data has changed, reducing unnecessary serial polling when the application supports it. Typical applications include microcontroller GPIO expansion, keypad and control panels, relay or indicator interfaces, industrial automation modules, communications equipment, and embedded systems using the site-listed STM32, ATMEGA, MSP430, or other microcontroller families. The same I2C bus can support multiple addressed peripherals, subject to the device address configuration and bus capacitance requirements. Designers should follow the manufacturer datasheet for pull-up resistor selection, address strapping, decoupling, input/output polarity, and interrupt handling. Confirm the available voltage range against the connected bus and peripherals, and verify absolute maximum ratings before using the device in systems with long cables or exposed connectors. The 16-pin PDIP package favors through-hole prototyping rather than compact surface-mount production. This page combines the verified manufacturer and distributor information for PCF8574N with package, selection, design, and application guidance. It is intended to help engineers identify whether the part fits a particular I2C expansion requirement before comparing alternatives or requesting supply.
PCF8574PW - 8-bit I2C I/O Expander 20-TSSOP | Texas Instruments (Tape & Reel)
The Texas Instruments PCF8574PW is a remote 8-bit I/O expander for the I2C bus, designed for 2.5 V to 6 V VCC operation, packaged in a 20-pin TSSOP (PW) with Tape and Reel packaging. It provides general-purpose remote I/O expansion for most microcontroller families via the I2C interface (serial clock SCL, serial data SDA) and supports an interrupt (INT) output to flag input changes to the host. An I/O expander is a type of interface IC that sits between a host controller (typically a microcontroller with limited GPIO) and external peripherals, translating a serial bus into multiple parallel digital lines. The PCF8574 belongs to the I2C I/O expander family -> interface IC -> integrated circuit -> semiconductor. By cascading multiple devices, designers can scale I/O count without redesigning the host board, making I/O expanders essential in space-constrained and pin-limited embedded designs. Key features include 8 quasi-bidirectional I/O pins, 100 kHz I2C clock rate, three hardware address pins (A0-A2) allowing up to 8 devices on the same bus (16 combined with PCF8574A), an active-low interrupt output that wakes the host on input changes, and low standby current of 2.5 uA typical. The PCF8574 uses the I2C address base 0x20 (PCF8574A uses 0x38), supporting up to 16 devices on a single bus for 128 I/Os. The quasi-bidirectional I/O architecture eliminates the need for a direction control register by using a clever pull-up/pull-down scheme, simplifying firmware. Each I/O can source 25 mA (LED drive capability) and sink up to 25 mA, sufficient to drive LEDs, keypads, or relay coils directly without buffering. Typical applications include keypad scanning for human-machine interfaces, LED driving for status indicators and display backlights, GPIO expansion for Raspberry Pi or ESP32-based projects, and industrial control panels. The wide 2.5 V to 6 V VCC range allows interfacing with both 3.3 V and 5 V logic without level shifters. When designing with this device, note that quasi-bidirectional I/Os are weak when transitioning to high - add an external pull-up resistor (typically 10 kohm) if driving heavy capacitive loads. The INT pin must be acknowledged by the host to clear the interrupt condition. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
PCF8574PWR - 8-bit I2C I/O Expander 20-TSSOP | Texas Instruments
The Texas Instruments PCF8574PWR is a remote 8-bit I/O expander for the I2C bus, designed for 2.5 V to 6 V VCC operation, packaged in a 20-pin TSSOP (PW) with Tape and Reel packaging. It provides general-purpose remote I/O expansion for most microcontroller families via the I2C interface (serial clock SCL, serial data SDA) and supports an interrupt (INT) output to flag input changes to the host. An I/O expander is a type of interface IC that sits between a host controller (typically a microcontroller with limited GPIO) and external peripherals, translating a serial bus into multiple parallel digital lines. The PCF8574 belongs to the I2C I/O expander family -> interface IC -> integrated circuit -> semiconductor. By cascading multiple devices, designers can scale I/O count without redesigning the host board, making I/O expanders essential in space-constrained and pin-limited embedded designs. Key features include 8 quasi-bidirectional I/O pins, 100 kHz I2C clock rate, three hardware address pins (A0-A2) allowing up to 8 devices on the same bus (16 combined with PCF8574A), an active-low interrupt output that wakes the host on input changes, and low standby current of 2.5 uA typical. The PCF8574 uses the I2C address base 0x20 (PCF8574A uses 0x38), supporting up to 16 devices on a single bus for 128 I/Os. The quasi-bidirectional I/O architecture eliminates the need for a direction control register by using a clever pull-up/pull-down scheme, simplifying firmware. Each I/O can source 25 mA (LED drive capability) and sink up to 25 mA, sufficient to drive LEDs, keypads, or relay coils directly without buffering. Typical applications include keypad scanning for human-machine interfaces, LED driving for status indicators and display backlights, GPIO expansion for Raspberry Pi or ESP32-based projects, and industrial control panels. The wide 2.5 V to 6 V VCC range allows interfacing with both 3.3 V and 5 V logic without level shifters. When designing with this device, note that quasi-bidirectional I/Os are weak when transitioning to high - add an external pull-up resistor (typically 10 kohm) if driving heavy capacitive loads. The INT pin must be acknowledged by the host to clear the interrupt condition. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.