PCA8575PW,118 - 16-bit I2C I/O Expander TSSOP-24 | NXP
MPN: PCA8575PW,118 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.92 | $1.92 |
| 10 | $1.72 | $17.20 |
| 100 | $1.43 | $143.00 |
| 500 | $1.18 | $590.00 |
| 1,000 | $1.04 | $1,040.00 |
PCA8575PW,118 Overview
An I/O expander is a bus-attach peripheral that multiplies a host controller's general-purpose I/O count by adding parallel input/output pins over a serial link. The PCA8575PW,118 belongs to the I2C-bus I/O expander family (I/O expander -> GPIO expander -> parallel I/O port -> interface IC -> integrated circuit). Quasi-bidirectional outputs can be driven low actively by the device or pulled high weakly, which lets a single pin directly sink LED current when configured as an output and still be read as a logic high when the external driver releases the line - useful for keypad scanning and switch-matrix polling.
Key features include 16 individually addressable I/O lines, an open-drain interrupt (INT) line that asserts when any input changes state, three hardware address pins (A0/A1/A2) allowing up to eight devices on one bus (128 I/O total), latched outputs with high-current drive capability suitable for direct LED driving, and a low standby current that suits battery-powered designs. The integrated address decoder, input filter, and edge-triggered interrupt block reduce host firmware overhead because the MCU only services the PCA8575PW,118 when an actual port event occurs.
Typical applications include adding pushbuttons, keypads, LED indicators, relay drivers, and sensor multiplexing to 8-pin microcontrollers, white-goods and appliance front panels, industrial PLC I/O modules, and PC accessory sideband ports. The 400 kHz Fast-mode I2C clock and 2.3 V to 5.5 V supply let it interface directly with 3.3 V ARM Cortex-M parts and 5 V legacy MCUs without level translation.
When designing with this device, place the standard 100 nF VCC bypass within 5 mm of the supply pin and add 10 kohm pull-ups on SDA and SCL - quasi-bidirectional outputs still require external pull-ups to drive logic high reliably. Reserve the INT pin for an MCU edge-triggered input and avoid tying it permanently high; the address pins A0-A2 must be tied to a fixed logic level and not left floating at power-up.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the NXP datasheet alone, including the comparison and pinout data that engineering teams need to qualify a second source.
Drop-in alternatives for PCA8575PW,118 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with PCA8575PW,118 (same form factor and footprint) — differing in Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PCA8575PW
✅ Drop-In📋 Reference alternative (not in catalog)
PCA8575BS
✅ Drop-In📋 Reference alternative (not in catalog)
PCA8575DGG
✅ Drop-In📋 Reference alternative (not in catalog)
PCA9555PW
✅ Drop-In✓ In Stock
Contact for price
View Datasheet →MCP23017-E/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PCA8575PW,118 Specifications
| Function | 16-bit I2C-bus I/O Expander with Interrupt |
| Number of I/O | 16 |
| Interface | I2C (SCL/SDA) |
| Clock Frequency (Max) | 400 kHz (Fast-mode) |
| Supply Voltage Range | 2.3 V to 5.5 V |
| I/O Type | Quasi-bidirectional |
| Interrupt Output | Yes (open-drain INT, active low) |
| Hardware Address Pins | 3 (A0, A1, A2 - up to 8 devices on bus) |
| Operating Temperature Range | -40 C to +85 C (industrial) |
| Package | 24-TSSOP (4.40 mm body width, 0.65 mm pitch) |
| Mounting Type | Surface Mount |
| Packaging | Digi-Reel (Tape & Reel) |
| MSL Level | 1 (per JEDEC J-STD-020) |
| RoHS Status | Compliant |
PCA8575PW,118 Pin Configuration
| Pin 1 | A0 — Hardware address input 0 |
| Pin 2 | A1 — Hardware address input 1 |
| Pin 3 | A2 — Hardware address input 2 |
| Pin 4 | P0.0 — Quasi-bidirectional I/O port 0, bit 0 |
| Pin 5 | P0.1 — Quasi-bidirectional I/O port 0, bit 1 |
| Pin 6 | P0.2 — Quasi-bidirectional I/O port 0, bit 2 |
| Pin 7 | P0.3 — Quasi-bidirectional I/O port 0, bit 3 |
| Pin 8 | P0.4 — Quasi-bidirectional I/O port 0, bit 4 |
| Pin 9 | P0.5 — Quasi-bidirectional I/O port 0, bit 5 |
| Pin 10 | P0.6 — Quasi-bidirectional I/O port 0, bit 6 |
| Pin 11 | P0.7 — Quasi-bidirectional I/O port 0, bit 7 |
| Pin 12 | VCC — Supply voltage (2.3 V to 5.5 V) |
| Pin 13 | SCL — I2C serial clock input |
| Pin 14 | SDA — I2C serial data I/O |
| Pin 15 | INT — Interrupt output (open-drain, active low) |
| Pin 16 | P1.0 — Quasi-bidirectional I/O port 1, bit 0 |
| Pin 17 | P1.1 — Quasi-bidirectional I/O port 1, bit 1 |
| Pin 18 | P1.2 — Quasi-bidirectional I/O port 1, bit 2 |
| Pin 19 | P1.3 — Quasi-bidirectional I/O port 1, bit 3 |
| Pin 20 | P1.4 — Quasi-bidirectional I/O port 1, bit 4 |
| Pin 21 | P1.5 — Quasi-bidirectional I/O port 1, bit 5 |
| Pin 22 | P1.6 — Quasi-bidirectional I/O port 1, bit 6 |
| Pin 23 | P1.7 — Quasi-bidirectional I/O port 1, bit 7 |
| Pin 24 | GND — Ground reference |
Typical Applications
PCA8575PW,118 is suitable for 6 applications: White Goods and Appliance Front Panels, Industrial PLC I/O Expansion Modules, Keypad and Switch-Matrix Scanning, LED Status Indicators and Signalling, Sensor Multiplexing and Aggregation, PC and Accessory Sideband Ports.
White Goods and Appliance Front Panels
The PCA8575PW,118's 16 quasi-bidirectional I/O lines plus interrupt output suit it to washing-machine, dishwasher, and microwave front-panel designs where each pushbutton, indicator LED, and rotary encoder needs a host-attached pin. With 2.3 V to 5.5 V supply and 400 kHz I2C, the part interfaces directly to a 3.3 V Cortex-M0 host MCU and supports three hardware address pins to stack up to 128 lines for high-end panels. Compared with discrete matrix scanning, the PCA8575PW,118 saves board space, reduces MCU pin count, and its INT output wakes the host only on a key event rather than polling the matrix at high frequency.
Recommended
Industrial PLC I/O Expansion Modules
In PLC digital-input and digital-output sub-modules, the PCA8575PW,118 acts as an optically-isolated I/O extender that brings 16 channels per chip to a backplane I2C bus. The interrupt output (INT) allows the PLC's main controller to react within one I2C transaction to a fast-changing input rather than continuously scanning 16 bits, which simplifies PLC firmware and lowers CPU load. The 2.3 V to 5.5 V supply range and industrial -40 C to +85 C rating fit the IEC 61131-2 industrial environment and the device's latched outputs with high-current drive can directly sink indicator LEDs on the operator panel.
Recommended
Keypad and Switch-Matrix Scanning
The PCA8575PW,118 is well-matched to 4x4 or 8x4 keypad scanning because its quasi-bidirectional I/O can be both driven low (active sink) and read back as a high (weak pull-up) on the same pin, eliminating the external diodes normally required for matrix isolation. The INT pin asserts on any input transition, so the host MCU sleeps in a low-power state until a key event occurs, saving significant current in battery-powered handheld devices. Three hardware address pins let the design scale to multiple keypads (for example, a 64-key industrial console) on one I2C bus with only four I/O pins consumed on the host.
Recommended
LED Status Indicators and Signalling
With latched outputs capable of directly driving LEDs and an I2C interface that needs only two host pins to control 16 indicators, the PCA8575PW,118 simplifies status and fault-LED arrays in networking equipment, server chassis, and instrumentation front panels. The quasi-bidirectional structure sinks LED current when the output is low, so each LED connects between VCC and the I/O pin through a single series resistor, and any input state change wakes the host via the INT line. Three address pins permit up to eight PCA8575PW,118 chips on one bus for 128 individually-controlled status indicators.
Recommended
Sensor Multiplexing and Aggregation
In IoT edge nodes that aggregate many low-bandwidth sensors (temperature, humidity, contact, PIR motion), the PCA8575PW,118 expands a small 8-pin MCU into 16 digital sensor inputs while consuming only two I2C pins and offering an interrupt-driven wakeup. The 2.3 V to 5.5 V supply allows the same chip to interface with both 3.3 V sensors and 5 V legacy sensors on the same node, and the 400 kHz I2C clock keeps the bus scan time well under 1 ms for all 16 inputs. The interrupt pin (INT) triggers the host MCU out of sleep whenever a sensor state changes, enabling aggressive duty-cycling in battery-powered designs.
Recommended
PC and Accessory Sideband Ports
The PCA8575PW,118 is widely used as a sideband GPIO expander in printers, scanners, multifunction devices, and docking stations where a host SoC needs additional control lines for paper sensors, cover-open switches, button matrices, and indicator LEDs. The TSSOP-24 package is small enough to fit beneath a connector shield, the 2.3 V to 5.5 V supply matches modern 3.3 V SoC rails, and the I2C interface can be shared with other low-bandwidth peripherals such as EEPROM or thermal sensors. Three hardware address pins support up to eight PCA8575PW,118 chips on one SMBus segment for high-pin-count accessories.
Recommended
Recommended Products Summary
Engineering reference data for PCA8575PW,118 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PCA8575PW | PCA8575BS | PCA8575DB,118 | PCA8575DGG | PCA9555PW | MCP23017-E/SP |
|---|---|---|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | Microchip Technology |
| Package | 24-TSSOP | 24-TSSOP - same | 24-TSSOP - same | 24-SSOP - different land pattern | 24-TSSOP - same | 24-TSSOP - same | 24-TSSOP (MCP23017-E/SS) - same |
| Number of I/O | 16 | 16 | 16 | 16 | 16 | 16 | 16 |
| Supply Voltage Range | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 1.8 V to 5.5 V (wider) |
| I2C Clock Frequency (Max) | 400 kHz | 400 kHz | 400 kHz | 400 kHz | 400 kHz | 400 kHz | 1.7 MHz (Fast-mode Plus) |
| I/O Type | Quasi-bidirectional | Quasi-bidirectional | Quasi-bidirectional | Quasi-bidirectional | Quasi-bidirectional | Push-pull (totem-pole) | Push-pull (configurable direction) |
| Interrupt Output | Yes (active low, open-drain) | Yes | Yes | Yes | Yes | Yes | Yes (two interrupt pins: INTA + INTB) |
| Hardware Address Pins | 3 (A0, A1, A2) | 3 | 3 | 3 | 3 | 3 | 3 (A0, A1, A2) |
| Max Devices per I2C Bus | 8 (128 I/O) | 8 (128 I/O) | 8 (128 I/O) | 8 (128 I/O) | 8 (128 I/O) | 8 (128 I/O) | 8 (128 I/O) |
Key Differentiators
- Quasi-bidirectional outputs simplify matrix wiring (vs MCP23017-E/SP)
- Higher Max I2C clock frequency and lower voltage option (vs PCA8575PW)
- Single INT pin, no per-port interrupt routing (vs MCP23017-E/SP)
Design Notes
Place a 100 nF X7R ceramic bypass capacitor within 5 mm of the PCA8575PW,118 VCC pin (pin 12) and connect its ground side directly to the GND pin (pin 24) with a short trace. The I2C bus SDA and SCL lines require external pull-up resistors - typical values are 4.7 kohm for 3.3 V and 5 V buses at 400 kHz with a few peripheral nodes, scaling down to 2.2 kohm when more devices or longer traces are added. Do not leave the INT pin floating - connect it to the host MCU's edge-triggered input with a pull-up to VCC.
The hardware address pins A0, A1, A2 must be tied to a fixed logic level (VCC or GND) at power-up and never left floating, or the PCA8575PW,118 may respond to an unexpected address and bus collisions will occur. Avoid reading input state immediately after writing to the same port - the NXP datasheet recommends a small delay or reading the port twice to filter transient mid-transition captures. The quasi-bidirectional outputs can actively sink but only weakly source current, so driving external loads that require high source current (e.g. low-impedance relays) without a transistor will not work.
Keep the I2C traces (SCL, SDA) short and parallel, route them away from switching converter nodes and high-current LED traces to minimize coupled noise, and place the SDA/SCL pull-up resistors close to the PCA8575PW,118 end of the bus. The TSSOP-24 thermal pad is not present on this package - standard copper pouring beneath the chip is sufficient for ground referencing. Avoid vias in the SDA/SCL traces when possible to reduce impedance discontinuities at 400 kHz.
Compliance Information
RoHS and REACH compliance per NXP product page; MSL 1 rated per JEDEC J-STD-020. Not AEC-Q100 qualified - this is a commercial/industrial-grade I/O expander, not an automotive part.
