Overview
The PCAL9538APWJ is an 8-bit I2C and SMBus low-power I/O expander manufactured by NXP USA Inc. This device is designed to provide general-purpose parallel input and output (I/O) expansion for systems using the two-line bidirectional I2C bus or SMBus protocol. It is particularly useful in applications where additional I/Os are needed for switches, sensors, push-buttons, LEDs, fans, and other similar components.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Power Supply Range | 2.3 V to 5.5 V | V |
| Standby Current Consumption | 1 μA max | μA |
| I2C Clock Frequencies | 100 kHz (Standard-mode), 400 kHz (Fast-mode) | kHz |
| ESD Protection | 2000-V Human-body model, 200-V Machine model, 1000-V Charged-device model | V |
| Interrupt Output | Open-drain active-low | |
| Address Pins | A0 and A1 (hardware selectable) | |
| Maximum Current per I/O | 25 mA | mA |
| Total Current Sourced by All I/Os | 85 mA | mA |
Key Features
- Low standby current consumption of 1 μA max, making it suitable for low-power applications.
- Supports both 100 kHz (Standard-mode) and 400 kHz (Fast-mode) I2C clock frequencies.
- ESD protection exceeds JESD 22 standards for human-body, machine, and charged-device models.
- Open-drain active-low interrupt output that can inform the microcontroller of input port changes without continuous I2C communication.
- Hardware selectable address pins (A0 and A1) allowing up to four devices on the same I2C bus.
- High-current drive capability for directly driving LEDs.
- Reset feature to default state via power-on reset or RESET pin.
Applications
- Expanding I/O capabilities in microcontrollers and other embedded systems.
- Control and monitoring of switches, sensors, push-buttons, LEDs, and fans.
- Industrial automation and control systems.
- Consumer electronics requiring additional I/O ports.
- Automotive and IoT applications where low power consumption is critical.
Q & A
- What is the PCAL9538APWJ used for?
The PCAL9538APWJ is used for expanding the I/O capabilities of microcontrollers and other embedded systems using the I2C or SMBus protocol.
- What is the power supply range of the PCAL9538APWJ?
The power supply range is from 2.3 V to 5.5 V.
- What are the supported I2C clock frequencies?
The device supports both 100 kHz (Standard-mode) and 400 kHz (Fast-mode) I2C clock frequencies.
- How many devices can be connected on the same I2C bus?
Up to four devices can be connected on the same I2C bus using the hardware selectable address pins (A0 and A1).
- What is the maximum current per I/O?
The maximum current per I/O is 25 mA.
- What is the total current sourced by all I/Os?
The total current sourced by all I/Os must be limited to 85 mA.
- Does the PCAL9538APWJ have ESD protection?
- How can the device be reset to its default state?
The device can be reset to its default state by using the RESET feature or by cycling the power supply to cause a power-on reset.
- What is the purpose of the interrupt output?
The interrupt output informs the microcontroller of input port changes without continuous I2C communication.
- Can the PCAL9538APWJ directly drive LEDs?
