PCF8575CDB - 16-Bit I2C I/O Expander | Texas Instruments
MPN: PCF8575CDB ✓ فعالPCF8575CDB نمای کلی
An I2C I/O expander is a peripheral interface device that converts a serial two-wire connection into additional parallel input or output lines. It belongs to the interface IC hierarchy, where an I/O expander sits between a host microcontroller and external control or sensing circuits. This parallel-to-serial expansion reduces pin count and allows buttons, LEDs, relays, or digital status signals to be connected over a shared bus.
The PCF8575CDB provides 16 general-purpose remote I/O lines, three hardware address inputs, SCL and SDA bus connections, an active-low open-drain interrupt output, a 2.5 V to 5.5 V supply range, and operation up to 400 kHz. Three address pins permit eight distinct bus addresses. The interrupt output also supports low standby-current operation, with a maximum standby-current figure of 10 uA identified in the manufacturer documentation.
Communication with the device occurs through the two-wire I2C or SMBus-compatible interface. The address pins select the device address without additional external components, while the interrupt line allows the host to avoid continuous polling when a monitored remote input changes state. As a quasi-bidirectional I2C interface, the implementation should be evaluated against the pull-up and bus-drive requirements described in the manufacturer datasheet.
Typical uses include expanding microcontroller GPIO for LED indicators and pushbuttons, reading switches and interlocks, controlling relay or solenoid drivers, and building keypad or alarm panels. The 16-bit port is especially useful where a controller must monitor more inputs or drive more outputs than its native package allows. Multiple devices can share the bus when their hardware address pins are configured differently.
PCB implementation requires correct pull-up placement for SDA and SCL, unobstructed routing between the expander and its address-setting hardware, and adequate decoupling near the supply pins. Because the interrupt output is open drain, its external pull-up must also be arranged to suit the host’s input and operating voltage. Confirm package pin numbering and signal names against the manufacturer datasheet before finalizing the board layout.
This product page combines the manufacturer’s electrical and ordering information with practical implementation guidance, drop-in replacement analysis, and application-oriented design notes. It helps engineers evaluate whether the PCF8575CDB’s 16 lines, addressability, interrupt behavior, and 400 kHz bus capability fit a new embedded control design.
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درخواست جایگزینPCF8575CDB مشخصات
| Device Type | 16-bit I2C/SMBus I/O expander |
| Number of I/O Lines | 16 lines |
| رابط | I2C/SMBus |
| Maximum I2C Bus Frequency | 400 kHz |
| Operating Supply Voltage Range | 2.5 V to 5.5 V |
| Standby Current | 10 uA maximum |
| Interrupt Output | Open drain |
| Hardware Address Inputs | 3 inputs |
| Maximum Devices per Bus | 8 devices |
| Bus Signals | SCL and SDA |
| Remote I/O Port | 16 quasi-bidirectional I/O lines |
| بسته‌بندی | 24-pin SSOP |
| Package Code | DB |
| Terminal Count | 24 terminals |
| Package Shape | Rectangular |
| Mounting Form | Gull wing |
| Temperature Grade | Industrial |
پیکربندی پین PCF8575CDB
| پین 1 | A0 — Hardware address input A0 |
| پین 2 | A1 — Hardware address input A1 |
| پین 3 | A2 — Hardware address input A2 |
| پین 4 | SCL — Serial clock input |
| پین 5 | SDA — Serial data input/output |
| پین 6 | P0 — Remote I/O port line P0 |
| پین 7 | P1 — Remote I/O port line P1 |
| پین 8 | P2 — Remote I/O port line P2 |
| پین 9 | P3 — Remote I/O port line P3 |
| پین 10 | P4 — Remote I/O port line P4 |
| پین 11 | P5 — Remote I/O port line P5 |
| پین 12 | P6 — Remote I/O port line P6 |
| پین 13 | P7 — Remote I/O port line P7 |
| پین 14 | INT — Open-drain interrupt output |
| پین 15 | P15 — Remote I/O port line P15 |
| پین 16 | P14 — Remote I/O port line P14 |
| پین 17 | P13 — Remote I/O port line P13 |
| پین 18 | P12 — Remote I/O port line P12 |
| پین 19 | P11 — Remote I/O port line P11 |
| پین 20 | P10 — Remote I/O port line P10 |
| پین 21 | P9 — Remote I/O port line P9 |
| پین 22 | P8 — Remote I/O port line P8 |
| پین 23 | VCC — Power supply input |
| پین 24 | GND — Ground reference |
کاربردهای معمول
PCF8575CDB مناسب است برای 6 کاربردs: Microcontroller GPIO Expansion, LED and Indicator Control, Pushbutton and Switch Input Panel, Relay and Solenoid Control, Keypad and Human-Machine Interface, Industrial Sensor and Alarm Interface.
Microcontroller GPIO Expansion
The PCF8575CDB fits designs in which a host controller needs more digital lines than its native package provides. Its 16 remote I/O lines connect over I2C at up to 400 kHz while the MCU retains control through the shared SDA and SCL bus. The 2.5 V to 5.5 V operating range supports common embedded rails, and the open-drain interrupt output lets firmware respond to a selected port event without continuously polling all 16 lines. Designers should assign the address pins uniquely among up to eight bus devices and verify the external pull-up network against the host voltage and bus capacitance.
پیشنهادی
LED and Indicator Control
The PCF8575CDB is suitable for driving grouped LED indicators from a microcontroller that lacks enough direct outputs. Sixteen remote output lines can operate display or status LEDs through suitable current-limiting and drive circuitry, while the host updates the port through the I2C bus at rates up to 400 kHz. The open-drain interrupt output is less important for pure output use but remains available for coordinating with other expander inputs. Because port behavior and current limits are defined by the manufacturer datasheet, check each LED drive path and ensure the controller and expander share a compatible logic voltage.
پیشنهادی
Pushbutton and Switch Input Panel
A PCF8575CDB can collect switch, pushbutton, or interlock states across 16 lines and report changes to a host controller. Its three hardware address pins allow as many as eight expanders to share an I2C bus, which supports distributed panels without allocating a separate GPIO bus per location. The open-drain interrupt output provides a practical way to signal the controller after an input condition changes. Firmware must account for input semantics and any pull-up arrangement used by the connected switches, and the design should debounce mechanical contacts in software or with suitable external circuitry.
پیشنهادی
Relay and Solenoid Control
The PCF8575CDB can provide a compact remote control interface for relays, solenoids, or other digital loads when the host microcontroller has insufficient output pins. The expander handles port updates over I2C, while external transistors or driver circuits isolate the 2.5 V to 5.5 V logic from higher-current or higher-voltage loads. The open-drain interrupt output can also coordinate status handling with other system events. A production design must include flyback protection for inductive loads, appropriate base or gate drive, and a documented startup state that prevents unintended actuator activation.
پیشنهادی
Keypad and Human-Machine Interface
The PCF8575CDB can expand the available I/O for a keypad, menu panel, or compact human-machine interface built around an I2C-capable controller. Its 16 lines can support scanned switch groups or status indicators, and the 400 kHz bus capability provides ample bandwidth for ordinary interaction rates. The interrupt output can alert firmware when an input event occurs, although scanning and debounce behavior still depend on the attached circuit and software design. Engineers should allocate bus addresses carefully when several interface panels share one controller and should test signal integrity with realistic wiring and bus capacitance.
پیشنهادی
Industrial Sensor and Alarm Interface
The PCF8575CDB can consolidate digital alarm, sensor, and equipment-status inputs on an industrial embedded controller with limited GPIO. Multiple expander addresses support distributed I/O modules, while the open-drain interrupt output provides a hardware indication of a changed port state. The 2.5 V to 5.5 V range permits use with conventional embedded logic rails, and the 400 kHz interface supports routine status polling and updates. Industrial implementations should include input conditioning, isolation where required, robust pull-up design, and fail-safe power states so that a reset or bus fault does not produce an unintended machine action.
پیشنهادی
خلاصه محصولات پیشنهادی
داده‌های مرجع مهندسی برای PCF8575CDB — مقایسه، راهنمای طراحی و اطلاعات انطباق.
راهنمای انتخاب
مقایسه با جایگزین‌ها
| پارامتر | این محصول |
|---|---|
| Package | 24-pin SSOP |
| Brand | Texas Instruments |
| I/O Count | 16 lines |
| Interface | I2C/SMBus |
| Maximum Bus Frequency | 400 kHz |
| Supply Voltage Range | 2.5 V to 5.5 V |
| Interrupt Output | Open drain |
| Hardware Address Inputs | 3 inputs |
| Maximum Devices per Bus | 8 devices |
| Standby Current | 10 uA maximum |
تفاوت‌های کلیدی
- 16 remote I/O lines in a defined 24-pin SSOP implementation (در مقابلPCA9554PWR)
- Up to eight devices per bus using three hardware address inputs (در مقابلPCA9534PWR)
- Open-drain interrupt support for event-driven host control (در مقابلPCA9538DWR)
یادداشت‌های طراحی
Place the I2C pull-up resistors and any interrupt pull-up close to the master device or the bus segment where the connected devices can source the required current. Route SCL and SDA away from switching nodes and high-current edges. Three address pins support eight devices, but every device on the shared bus must have a unique address. Keep the address-trace lengths similar where practical to reduce sensitivity to unequal propagation delays.
Do not substitute an expander solely because it also has 16 I/O lines. Verify the complete 24-pin SSOP footprint, pin numbering, port order, address pins, interrupt polarity, supply limits, and I2C timing against the manufacturer datasheet. A functionally similar device can use a different pinout and still require a PCB redesign. Firmware must also account for the port’s documented power-on behavior rather than assuming every output begins low.
Provide local supply decoupling and a continuous ground return for the expander. Connect unused inputs only in a manner permitted by the manufacturer pin description, and avoid assigning a floating input to a function that can create excessive current. Because the interrupt output is open drain, use a pull-up voltage that remains compatible with the host input while keeping the pin within its electrical limits. Review signal paths that connect long external wiring to the remote I/O port.
اطلاعات انطباق
No explicit RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals statements appear in the available product information. The industrial temperature grade does not by itself establish AEC-Q100 qualification.