PCF8575PW - 16-Bit I2C I/O Expander | Texas Instruments
Артикул: PCF8575PW ✗ Снят с производстваPCF8575PW Обзор
An I/O expander is an interface IC that converts a serial two-wire bus into additional parallel input and output lines. In the product hierarchy, the PCF8575 belongs to the I/O expander class, interface ICs, and integrated circuits. It allows a microcontroller with limited GPIO pins to control or monitor additional external signals without requiring a large number of direct host-controller pins.
Key features include 16 individually controlled I/O lines, an open-drain interrupt output, and a maximum standby-current consumption of 10 µA. The three address pins allow up to eight PCF8575 devices to share an I2C bus. Outputs are latched and have high-current drive capability for directly driving LEDs, while a current source to VCC supports actively driving a high output state.
The PCF8575 interface uses SCL and SDA for serial communication and provides an open-drain interrupt for signaling the host controller. Its 400 kHz fast-I2C capability suits embedded control systems operating at moderate bus rates. The device is compatible with most microcontrollers, making it useful where firmware and board space make another dedicated parallel interface impractical.
Typical uses include LED panels, key scanners, relay or switch controls, sensor and switch inputs, and general-purpose remote I/O in industrial, consumer, communications, and embedded systems. Each of the 16 I/O ports can be configured as an input or output through the serial interface, while the interrupt output can reduce unnecessary host-controller polling.
Designers should account for the open-drain nature of the interrupt and I2C bus, provide suitable pull-up resistors, confirm address configuration, and review the datasheet for power-on output states and current limits. External drivers may be required when a load exceeds the device's specified drive capability.
This page consolidates verified manufacturer and distributor information, documents where detailed ratings are unavailable, and distinguishes true package-compatible alternatives from look-alike expanders whose register behavior differs. It also provides application-specific engineering guidance that helps engineers evaluate the PCF8575PW before committing it to an existing PCB.
Аналоги без доработки для PCF8575PW — тот же корпус, pin-to-pin совместимость. Компоненты в других корпусах, требующие переработки PCB, исключены.
Варианты в этой серии
Модели той же серии, совместимые без доработки с PCF8575PW (тот же форм-фактор и посадочное место) — отличается по Package, Hardware Address Inputs, Interface Type, Output Drive Capability.
PCF8575CPWR
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PCF8575PWR
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Открыть даташит →PCF8575PWRG4
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PCF8575PWE4
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PCA9555PW
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Открыть даташит →PCF8575PW Характеристики
| Number of I/O Ports | 16 ports |
| Operating Supply Voltage Range | 2.5 V to 5.5 V |
| Тип интерфейса | I2C/SMBus, 2-wire serial |
| Maximum I2C Bus Frequency | 400 kHz |
| Hardware Address Inputs | 3 inputs, supporting up to 8 devices |
| Interrupt Output | Open-drain |
| Maximum Standby Current | 10 µA |
| Output Port Configuration | 16 individually latched ports |
| Output Drive Capability | High-current LED drive capability |
| High-Level Output Drive | Current source to VCC |
| Microcontroller Compatibility | Compatible with most microcontrollers |
| Корпус | 24-pin TSSOP (PW) |
| Тип монтажа | Surface mount |
Руководство по цоколевке PCF8575PW в корпусе 24-pin tssop (pw)
Цоколевка для PCF8575PW (корпус 24-pin tssop (pw)). Нумерация выводов, функции и схемы подключения определены в техническом описании производителя. Обратитесь к нему для точного посадочного места и рекомендаций по пайке.
Нет подробных данных о распиновке для PCF8575PW.
Обратитесь к даташиту для полной конфигурации выводов.
Типичное применение
PCF8575PW подходит для 6 применениеs: LED Status and Indicator Panels, Industrial Switch and Relay Inputs, Matrix Keypad Scanning, Remote Sensor and Discrete Signal Monitoring, Communications Equipment Control Panels, Consumer and Embedded Control Interfaces.
LED Status and Indicator Panels
The PCF8575PW is suitable for LED panels because it provides 16 latched outputs with documented high-current LED drive capability, a 2.5 V to 5.5 V supply range, and a 400 kHz I2C interface. A microcontroller can update several indicators through one serial address instead of consuming one GPIO pin per LED. In a 5 V design, the current source to VCC supports an actively driven high state. The designer must still verify per-port and aggregate current limits, use the correct resistor values, and avoid exceeding thermal limits when many outputs are active simultaneously.
Рекомендуется
Industrial Switch and Relay Inputs
The PCF8575PW can expand a controller with limited GPIO into a bank of switch, sensor, or relay-command inputs while preserving a compact serial connection to the host. Its 16 ports support general-purpose I/O, and the open-drain interrupt can signal the controller when an input event occurs. In an industrial control board, the expander should sit behind appropriate isolation, filtering, surge protection, and common-mode controls. Firmware must also define valid power-on states so that external actuators do not enter an unsafe condition during reset.
Рекомендуется
Matrix Keypad Scanning
A PCF8575PW can accommodate keypad scanning by using a portion of its 16 ports for row and column functions and using the remaining ports for controls or indicators. The 400 kHz I2C rate provides sufficient bandwidth for ordinary human-interface key scanning, while three address inputs allow multiple expanders to coexist. Because the ports are multiplexed with other functions, the pin assignments must match the actual keypad orientation and the host firmware must account for scan timing, key debounce, ghost-key combinations, and the default state of every port during startup.
Рекомендуется
Remote Sensor and Discrete Signal Monitoring
The PCF8575PW is appropriate when a system must read more digital status signals than the host controller exposes directly. Sixteen configurable ports can monitor switches, interlocks, alarm lines, or digital sensor outputs, and the open-drain interrupt provides a dedicated alert path. Its 2.5 V minimum operating voltage allows use in 3.3 V equipment. For sensors with analog outputs, separate ADC circuitry remains necessary; the expander is intended for digital levels and must be protected from voltage levels, leakage, and transients that exceed the device's specifications.
Рекомендуется
Communications Equipment Control Panels
The PCF8575PW can add front-panel LED indicators, relay controls, and status inputs to a communications module without increasing the host processor's pin count. Its 400 kHz I2C operation is suitable for moderate-rate control traffic, and the three address inputs support additional expanders in a multi-function chassis. A network interface controller can monitor the panel through the interrupt line and update it through the same bus. Board-level design must maintain compatible logic levels, provide bus pull-ups, separate sensitive communication circuits from switching loads, and validate the interrupt handling during resets.
Рекомендуется
Consumer and Embedded Control Interfaces
The PCF8575PW is useful in compact embedded products that need several push buttons, indicators, or simple actuator connections but have a microcontroller with a limited pin budget. The device is compatible with most microcontrollers and operates across 2.5 V to 5.5 V, making it suitable for common embedded supply levels. Its maximum 10 µA standby current is useful in power-conscious designs. Firmware should initialize ports before enabling attached loads, and the hardware should include adequate bus pull-ups and any current-limiting or protection required by the connected peripherals.
Рекомендуется
Сводка рекомендуемых товаров
Справочные инженерные данные для PCF8575PW — сравнение, рекомендации по проектированию и информация о соответствии.
Руководство по выбору
Сравнение с аналогами
| Параметр | Этот товар | PCF8575CPWR | PCF8575PWR | PCF8575PWRG4 | PCF8575PWE4 | PCA9555PW |
|---|---|---|---|---|---|---|
| Package | TSSOP-24 (PW) | TSSOP-24 (PW) | TSSOP-24 (PW) | TSSOP-24 (PW) | TSSOP-24 (PW) | TSSOP-24 (PW) |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Number of I/O Ports | 16 | 16 | 16 | 16 | 16 | 16 |
Ключевые отличия
- Lower operating-voltage boundary than the verified TCA6416PW comparison candidate (против TCA6416PW)
- Documented 400 kHz I2C performance (против PCA9555PW)
- Open-drain interrupt with three-address-device support (против PCF8575PWR)
Заметки по проектированию
Do not substitute a functionally similar I/O expander solely because both devices are described as 16-bit expanders. The verified Texas Instruments support comparison shows that the PCA9555 presents its I/O pins as inputs at power-on or reset, while the PCF8575 application in that report did not provide the required low output state. Before replacing PCF8575PW, compare the numbered pinout, address scheme, register map, interrupt polarity, port direction defaults, and output-current limits against the manufacturer datasheet.
Place the PCF8575PW close to the SDA and SCL routing, with pull-up resistors positioned at appropriate bus endpoints and chosen using the device's input-current and bus-capacitance requirements. Keep the interrupt line short and provide its required pull-up. Route each expander address pin decisively to ground or the appropriate supply level, and separate traces driving inductive or high-current loads to reduce coupling into the 400 kHz serial bus.
Initialize all 16 outputs to their intended safe levels before enabling attached relays, LEDs, or other loads. The verified excerpts do not provide the complete PCF8575 power-up output-state table or current limits, so use the manufacturer datasheet for startup behavior. Check both the aggregate supply current and the worst-case distribution across ports, and provide local decoupling that does not disrupt the I2C routing or interrupt return path.
Информация о соответствии
The supplied verified excerpts identify the manufacturer, package, electrical highlights, and ordering information but do not explicitly provide RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals statements. Compliance must be confirmed from the current Texas Instruments product documentation before qualification.