PCA9535CD - 16-Bit I2C GPIO Expander | NXP Semiconductors
料号： PCA9535CD ✓ 量产中PCA9535CD 概述
An I/O expander is an interface IC that extends the number of general-purpose digital lines connected to a host controller. The PCA9535 and PCA9535C belong to this low-power CMOS I/O-expander family and were developed for I2C-bus and SMBus applications. Each port pin can operate as an input or output, allowing one serial bus to control multiple discrete signals while reducing the number of package pins required by the host microcontroller.
The PCA9535CD supports 16 GPIO lines, a 400 kHz I2C clock, a 2.3 V to 5.5 V operating supply range, and an interrupt mechanism for connected peripherals. Unlike devices fitted with internal I/O pull-up resistors, the PCA9535 omits those pull-ups, reducing power consumption when its output ports are held LOW. External pull-ups can still be added when the connected circuit requires them. Software configuration determines each port's input or output direction.
NXP documents the device as pin-to-pin and I2C-address compatible with the PCF8575, although enhancements require software changes described in Application Note AN469. The PCA9535 is also described as identical to the PCA9555 except for removal of the internal I/O pull-up resistor. These relationships make the PCA9535 useful when a design requires the enhanced interrupt behavior and port features of the PCA9535 while retaining compatibility with established software architectures.
Typical uses include expanding microcontroller GPIO for LEDs, push buttons, logic-level control signals, and peripheral interface signals. It can also serve industrial, embedded, and communications equipment where a serial-to-parallel expansion is preferable to adding another microcontroller or a larger host package. The interrupt output can provide an efficient way to notify the host of a change at a connected input rather than requiring continuous polling.
Designers should confirm the device's I2C address, address pins, interrupt configuration, and external pull-up requirements before finalizing a board. The bus must also remain within the specified 2.3 V to 5.5 V supply range and 400 kHz clock limit. Because the PCA9535 has no internal I/O pull-ups, input leakage, voltage thresholds, and external bus pull-ups must be evaluated together to ensure reliable logic levels.
This page combines the verified NXP product information with distributor availability and pricing, strict same-package alternatives, application guidance, and design considerations. The information is intended to help engineers determine compatibility, sourcing, and implementation requirements without treating electrically similar but mechanically different devices as drop-in replacements.
直接替换替代料： PCA9535CD ——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： PCA9535CD （相同外形与封装尺寸） ——差异在于 Device Type, Package.
PCA9555PW
✅ 直接替换联系询价
查看数据手册 →PCF8575
✅ 直接替换📋 参考替代料（不在目录中）
PCA9535CD 规格参数
| Number of I/O Ports | 16 ports |
| Number of GPIO Pins | 16 pins |
| 接口类型 | I2C-bus and SMBus |
| Maximum I2C Clock Frequency | 400 kHz |
| 工作电源电压 | 2.3 V to 5.5 V |
| Device Type | CMOS I/O expander |
| Port Configuration | 16 configurable input or output pins |
| Interrupt Output | 1 active-low open-drain interrupt output |
| Internal I/O Pull-Up Resistors | Not fitted |
| 封装 | 24-pin SOIC, 7.50 mm body width |
| 安装类型 | Surface mount |
| Packaging | Tape and reel |
| I2C Address Compatibility with PCF8575 | Compatible; software changes required |
| Pin Compatibility with PCF8575 | Pin-to-pin compatible |
| Relationship to PCA9555 | Identical except for removal of internal I/O pull-up resistors |
| Application Reference | NXP Application Note AN469 |
PCA9535CD 24-pin soic, 7.50 mm body width 引脚配置指南
PCA9535CD（24-pin soic, 7.50 mm body width 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： PCA9535CD.
请参阅 数据手册 以查看完整引脚配置。
典型应用
PCA9535CD 适用于 6 应用s: Embedded GPIO Expansion, Industrial Control Signal Conditioning, LED and Indicator Control, Communications Equipment Backplane Control, Instrumentation and Test Equipment, Low-Power Sensor and Peripheral Interface.
Embedded GPIO Expansion
The PCA9535CD fits embedded designs that need more digital lines than the host controller can expose directly. Its 16 GPIO pins can be configured individually as inputs or outputs through the I2C interface, allowing a microcontroller to supervise buttons, status indicators, or discrete peripheral controls without requiring a larger host package. The 2.3 V to 5.5 V operating range supports both 3.3 V and 5 V systems. Because the PCA9535 has no internal I/O pull-ups, the designer must verify external pull-up requirements and input leakage. According to the NXP product information, omitting the internal pull-ups reduces power consumption when ports are held LOW, making explicit input-bias analysis especially important.
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Industrial Control Signal Conditioning
The PCA9535CD is useful in industrial control boards where a compact controller must collect digital field signals and operate discrete control outputs. Sixteen configurable ports provide a uniform interface to limit switches, status flags, and actuator-enable signals over I2C. Its interrupt output can reduce unnecessary bus polling when an attached circuit changes state. The 2.3 V to 5.5 V range supports common industrial logic rails, but cable-connected inputs still require careful grounding, isolation, surge protection, and logic-threshold review. Since the PCA9535 does not include internal I/O pull-ups, every input path should be assessed for leakage, biasing, open-circuit behavior, and noise immunity before production release.
推荐
LED and Indicator Control
The PCA9535CD can concentrate low-current LED and indicator drive beneath a serial-control architecture. Its 16 output ports reduce the number of direct host-controller connections needed for panel indicators, while the 400 kHz I2C interface provides sufficient control bandwidth for ordinary status updates. The absence of internal I/O pull-ups is advantageous when outputs are continuously held LOW because it reduces unnecessary current consumption. Engineers should still calculate worst-case current per port and total device dissipation, and ensure that the LED current does not exceed the output limits in the manufacturer datasheet. External current-limiting resistors and an appropriate supply arrangement are required.
推荐
Communications Equipment Backplane Control
The PCA9535CD suits communications equipment that distributes module-present, reset, fault, or enable signals over a shared I2C bus. Sixteen ports provide enough density for several control functions on one interface, and the interrupt line can alert the host when a monitored input changes. The device's 400 kHz bus limit and 2.3 V to 5.5 V supply range align with many embedded backplanes, although the designer should account for bus capacitance, pull-up selection, and cable length. NXP confirms I2C-address and pin compatibility with the PCF8575 but notes required software changes, making register-level validation essential when adapting existing communications firmware.
推荐
Instrumentation and Test Equipment
In instrumentation and test equipment, the PCA9535CD can add front-panel and fixture-control lines while preserving a compact controller footprint. The 16 GPIO ports can operate inputs or outputs under firmware control, making the device suitable for range selection, relay-control commands, and status capture. The 2.3 V to 5.5 V range allows operation across common laboratory logic systems, while the 400 kHz I2C interface is adequate for modest control traffic. Designers should avoid assuming the internal pull-ups of the closely related PCA9555 are present, and should account for leakage, switch bounce, isolation, and the response time required when changing measurement ranges.
推荐
Low-Power Sensor and Peripheral Interface
The PCA9535CD is appropriate for compact sensor hubs and peripheral boards where power consumption and connector count are constrained. Sixteen configurable lines can monitor sensor-ready signals or control low-power peripherals while the host communicates through I2C. NXP specifically identifies the removal of internal I/O pull-ups as reducing power consumption when I/O ports are held LOW, which is valuable in duty-cycled equipment. However, the same omission means that external biasing may be needed to establish valid logic levels. The designer should quantify leakage across connected sensors, examine idle current in the actual operating mode, and confirm that the interrupt path remains usable when the main host is in a low-power state.
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推荐产品汇总
工程参考数据： PCA9535CD ——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 | PCA9555 | PCF8575 |
|---|---|---|---|
| Package | 24-pin SOIC | 24-pin SOIC | 24-pin SOIC |
| Brand | NXP Semiconductors | NXP Semiconductors | Texas Instruments |
| Number of I/O Ports | 16 ports | 16 ports | 16 ports |
| Interface | I2C-bus and SMBus | I2C-bus and SMBus | I2C-bus and SMBus |
| PCF8575 Hardware Compatibility | Pin-to-pin and I2C-address compatible; software changes required | Not applicable | Reference device |
关键差异点
- Lower potential standby consumption with outputs held LOW （对比 PCA9555)
- Established hardware migration path （对比 PCF8575)
- Complete 16-line parallel expansion （对比 PCF8575)
设计说明
Place the PCA9535CD close to the devices whose signals it supports and keep the I2C route away from noisy switching nodes. The verified data identifies a 24-pin SOIC package, so the footprint and pad geometry must match that package exactly. Confirm power, ground, address, interrupt, and all 16 I/O assignments against the exact datasheet pinout before releasing artwork.
The PCA9535 omits internal I/O pull-up resistors, so every external input and any I2C bus requiring pull-ups must be evaluated independently. Check leakage from connected devices, valid high-level voltage, and worst-case LOW-state current. Adding external pull-ups can increase system power, so select the largest resistance that still satisfies rise-time and sink-current requirements.
Do not treat the PCF8575 relationship as a firmware-identical substitution. NXP states that the PCA9535 is pin-to-pin and I2C-address compatible with the PCF8575, but software changes are required for the enhancements and are discussed in Application Note AN469. Review register behavior, interrupt handling, port defaults, and pull-up assumptions before replacing either device.
Keep the I2C bus at or below its verified 400 kHz maximum and account for bus capacitance when setting pull-up values. For long branches or slow edges, add a buffer such as the site-listed PCA9515AD only after confirming that the additional device's direction, address handling, and electrical characteristics support the topology. Stubs should be minimized to reduce reflections.
合规信息
The supplied verified data does not explicitly state target-part compliance for RoHS, REACH, AEC-Q100, lead-free status, halogen-free status, or conflict minerals.
