PCF8575DW - 16-Bit I2C I/O Expander | Texas Instruments
MPN： PCF8575DW ✓ 啟用中PCF8575DW 概覽
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.
直接替換替代品，適用於 PCF8575DW — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： PCF8575DW （相同外形與佔位） — 差異在於 Interrupt Output, Package, Device Type, Number of I/O Lines, Operating Temperature Range.
PCF8575DWR
✅ 直接替換聯絡詢價
查看資料表 →PCF8575CDWE4
✅ 直接替換📋 參考替代品（不在目錄中）
PCA9555DWR
✅ 直接替換✓ 有庫存
$2.4609 / 單位
查看資料表 →PCF8575DW 規格
| 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 |
| 介面 | I2C/SMBus |
| Interrupt Output | Open-drain |
| Hardware Address Pins | 3 |
| Maximum Addressable Devices | 8 devices |
| Standby Current | 10 uA maximum |
| 輸出類型 | Latched |
| Output Drive Capability | High-current drive capability |
| Output High Configuration | Current source to VCC for active-high drive |
| 工作溫度範圍 | -40 C to +85 C |
| 封裝 | 24-pin SOIC |
| Package Type | SOIC |
| 腳位數 | 24 |
| RoHS 狀態 | RoHS-compliant |
| 供應電壓 | 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 腳位配置指南
PCF8575DW（soic 封裝）的腳位配置。 腳位編號、功能與連接圖定義於製造商資料手冊中。請參閱該手冊以取得確切的封裝尺寸與焊接指引。
無詳細腳位定義資料： PCF8575DW.
請參閱 資料表 以查看完整腳位配置。
典型應用
PCF8575DW 適用於 6 應用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.
推薦
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.
推薦
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.
推薦
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.
推薦
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.
推薦
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.
推薦
工程參考資料，適用於 PCF8575DW — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | 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 |
主要差異化特點
- Verified 16-bit I/O expansion with three address pins (對比PCA9555DWR)
- Open-drain interrupt output for event-driven control (對比PCA9555DWR)
- 400 kHz Fast I2C operation (對比PCF8575CDWE4)
- Wide 2.5 V to 5.5 V supply compatibility (對比PCF8575DWR)
設計說明
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.
合規資訊
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.