PCF8575DW - 16-Bit I2C I/O Expander | Texas Instruments
料号： PCF8575DW ✓ 量产中PCF8575DW 概述
An I/O expander is an interface IC that translates serial bus commands into parallel digital input or output lines. The PCF8575 belongs to the I2C I/O expander category, within interface ICs and broader semiconductor power and signal-conditioning systems. Its design allows a host microcontroller to control or monitor multiple discrete digital signals while conserving the limited I/O pins available on small microcontrollers.
Key features include 16 I/O lines, an operating supply range of 2.5 V to 5.5 V, a maximum I2C clock frequency of 400 kHz, low standby-current consumption of 10 uA maximum, and an open-drain interrupt output. The outputs are latched and can provide high-current drive capability for directly driving LEDs. A current source connected to VCC also allows outputs to be actively driven high for systems that require an active-high output state.
The PCF8575DW communicates through SCL and SDA, with three address pins selecting one of eight possible bus addresses. The interrupt output provides a hardware indication that an input state has changed, allowing the host controller to respond without continuously polling the expander. The 400 kHz bus rate supports efficient transfers between the controller and the expanded I/O bank, while the 2.5 V to 5.5 V supply range supports both 3.3 V and 5 V systems.
Typical applications include industrial control panels, keypad and button interfaces, LED status indicators, relay or transistor control, sensor and switch monitoring, and general-purpose embedded system I/O expansion. The PCF8575DW is particularly suitable when a controller has insufficient GPIO pins for external switches, indicators, or actuators. Its interrupt output can reduce host processing time when multiple remote inputs require attention.
When designing around the PCF8575DW, confirm the controller's I2C voltage, pull-up resistor arrangement, address selection, and the electrical requirements of every connected load. The open-drain interrupt output requires appropriate pull-up treatment, and LED or relay loads must remain within the device's stated drive and current limits. The 24-pin SOIC footprint is intended for surface-mount PCB assembly.
This product page combines the verified manufacturer and distributor descriptions, packaging information, source links, and engineering-oriented design guidance for engineers evaluating the PCF8575DW. It distinguishes verified facts from unavailable detailed specifications and provides practical context for choosing a 16-bit I2C/SMBus I/O expander in embedded control designs.
直接替换替代料： PCF8575DW ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
本系列中的变体
可与以下型号直接替换的同系列型号： PCF8575DW （相同外形与封装尺寸） ——差异在于 Interrupt Output, Package, Device Type, Number of I/O Lines, Operating Temperature Range.
PCF8575DWR
✅ 直接替换联系询价
查看数据手册 →PCF8575CDWE4
✅ 直接替换📋 参考替代料（不在目录中）
PCA9555DWR
✅ 直接替换✓ 有现货
$2.4609 / 个
查看数据手册 →PCF8575DW 规格参数
| Device Type | Remote 16-bit I2C/SMBus I/O expander |
| Number of I/O Lines | 16 |
| Supply Voltage Range | 2.5 V to 5.5 V |
| I2C Maximum Clock Frequency | 400 kHz |
| 接口 | I2C/SMBus |
| Interrupt Output | Open-drain |
| Hardware Address Pins | 3 |
| Maximum Addressable Devices | 8 devices |
| Standby Current | 10 uA maximum |
| 输出类型 | Latched |
| Output Drive Capability | High-current drive capability |
| Output High Configuration | Current source to VCC for active-high drive |
| 工作温度范围 | -40 C to +85 C |
| 封装 | 24-pin SOIC |
| Package Type | SOIC |
| 引脚数 | 24 |
| RoHS 状态 | RoHS-compliant |
| 电源电压 | 3.3 V |
| Standby-Current Consumption | 10 uA maximum |
| I2C Bus Speed | 400 kHz fast mode |
| Addressing Method | Three hardware address pins |
| Input/Output Configuration | General-purpose remote digital I/O |
PCF8575DW soic 引脚配置指南
PCF8575DW（soic 封装）的引脚配置。 引脚编号、功能和连接图在制造商数据手册中定义。请参阅该手册以了解确切的封装尺寸和焊接指南。
暂无详细引脚数据： PCF8575DW.
请参阅 数据手册 以查看完整引脚配置。
典型应用
PCF8575DW 适用于 6 应用s: Industrial Control Panel I/O Expansion, LED Status and Indicator Control, Keypad and Switch Monitoring, Relay and Transistor Control, Remote Sensor and Digital Input Bank, Embedded Accessory and Peripheral Control.
Industrial Control Panel I/O Expansion
The PCF8575DW fits industrial control-panel designs that need more digital lines than the host controller provides. Its 16 general-purpose I/O lines can represent pushbuttons, selector switches, status lamps, or discrete actuator commands while the controller communicates through I2C. The verified 2.5 V to 5.5 V operating range supports common embedded supply levels, and the 400 kHz bus rate allows the controller to update the remote I/O bank efficiently. The open-drain interrupt output can notify the controller when an input changes, reducing unnecessary polling. Designers should still verify the drive current of every attached load and provide appropriate pull-up treatment for the interrupt line.
推荐
LED Status and Indicator Control
The PCF8575DW can provide a compact parallel output bank for LED status indicators, annunciators, and small panel lamps. Its 16 latched outputs allow the host microcontroller to update multiple indicator states through the I2C interface rather than dedicating one GPIO pin to every LED. The device's verified 400 kHz Fast I2C capability is useful when several visual states must be refreshed in sequence. The output drive capability and active-high current-source option make the device relevant to LED design, but current limits, polarity, and thermal conditions must be checked against the specific lamp and resistor arrangement before implementation.
推荐
Keypad and Switch Monitoring
A PCF8575DW can monitor a keypad, limit switches, or other discrete contact inputs when the main controller has too few GPIO pins. The three hardware address pins support up to eight devices on one bus, allowing several I/O banks to coexist as long as the address and interrupt wiring are planned correctly. The open-drain interrupt output provides an event-driven indication of a changed input, while the host controller reads the affected 16-bit bank over I2C. For reliable operation, the firmware should include debouncing, define the default state at power-up, and account for the device's electrical behavior rather than treating the expander as a general-purpose microcontroller GPIO.
推荐
Relay and Transistor Control
The PCF8575DW is useful as a remote command interface for relays, transistor gates, and other digital actuator drivers. It converts a serial I2C update into 16 latched parallel outputs, which simplifies control when the actuator wiring is located away from the main controller. The 16-bit output group allows multiple channels to be commanded together, and the interrupt output is available when the design also monitors an input or status signal. Because the outputs have defined drive limitations, the chosen relay driver, transistor, flyback network, and supply arrangement must remain within the device's verified electrical limits. The 24-SOIC package also requires adequate PCB spacing for the associated discrete protection components.
推荐
Remote Sensor and Digital Input Bank
The PCF8575DW can expand a small embedded controller into a bank of digital sensor inputs for limit detection, presence sensing, interlock signals, or digital alarm lines. The 16-bit I/O structure reduces serial-to-parallel conversion software complexity, while the three address pins allow multiple banks to share one I2C bus. The 2.5 V to 5.5 V supply range makes the device adaptable to 3.3 V and 5 V system architectures. Designers should confirm the input signal levels, external pull-ups, debounce strategy, and whether the interrupt output should remain enabled continuously. The open-drain interrupt is especially helpful for event-driven monitoring, but its pull-up arrangement must match the host controller's voltage domain.
推荐
Embedded Accessory and Peripheral Control
The PCF8575DW can add compact peripheral-control capability to a controller board that already uses its GPIO pins for primary functions. Typical uses include accessory enable lines, display or indicator controls, alarm outputs, and simple bus-facing status signals. Because the device uses the established I2C/SMBus serial interface, the host firmware can update 16 outputs through the same two-wire bus used for other peripherals. The 400 kHz operating rate supports responsive control without requiring a high-speed parallel expansion bus. A practical design should reserve correct pull-ups on SCL and SDA, avoid excessive bus loading, and verify the I/O voltage levels when the controller and accessory circuitry use different supply domains.
推荐
工程参考数据： PCF8575DW ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | PCF8575DWR | PCF8575CDWE4 | PCA9555DWR |
|---|---|---|---|---|
| Device Type | 16-bit remote I2C/SMBus I/O expander | PCF8575 I/O expander | PCF8575 I/O expander | 16-bit I/O expander candidate |
| Number of I/O Lines | 16 | 16 | 16 | 16 |
| Interface | I2C/SMBus | I2C/SMBus | I2C/SMBus | I2C |
| Package | 24-pin SOIC | 24-pin SOIC | 24-pin SOIC | 24-pin SOIC |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
关键差异点
- Verified 16-bit I/O expansion with three address pins （对比 PCA9555DWR)
- Open-drain interrupt output for event-driven control （对比 PCA9555DWR)
- 400 kHz Fast I2C operation （对比 PCF8575CDWE4)
- Wide 2.5 V to 5.5 V supply compatibility （对比 PCF8575DWR)
设计说明
Keep the I2C pull-up arrangement and the PCF8575DW power connections close to the device and host controller. The SCL and SDA lines should use pull-ups appropriate to the selected 2.5 V to 5.5 V operating range, and the PCB should preserve the manufacturer's recommended decoupling and exposed routing requirements for the 24-SOIC footprint. Verify address pins before fabrication because their levels determine the device address.
Do not assume that a 24-SOIC package alone guarantees drop-in compatibility. The PCF8575DW's verified 16-bit I/O arrangement, three hardware address pins, open-drain interrupt output, supply range, and 400 kHz I2C behavior must all be compared with the candidate datasheet. In particular, verify the interrupt polarity, pull-up requirements, address encoding, and output drive limits before substituting another manufacturer or family member.
Treat SCL and SDA as a defined I2C routing problem rather than as general-purpose logic nets. Keep the bus away from noisy switching nodes, maintain appropriate pull-up values for the bus capacitance and voltage, and use the three address pins with deliberate logic levels. When the open-drain interrupt is used, route it as an interrupt signal with a suitable pull-up and avoid excessive loading from unrelated circuitry.
合规信息
RoHS compliance is identified in the verified PCF8575DW technical and distributor results. The supplied data does not establish REACH, lead-free, halogen-free, or conflict-minerals status. AEC-Q100 is not applicable to the verified general-purpose interface-device description.