Overview
The PCA9538PW, produced by Texas Instruments, is an 8-bit I2C-bus and SMBus low-power I/O port expander. This device is designed to provide general-purpose parallel input/output (I/O) expansion for applications requiring additional I/Os. It operates within a power supply voltage range of 2.3 V to 5.5 V, making it versatile for various system designs. The PCA9538PW is part of the NXP Semiconductors family of I/O expanders, although it is also available through Texas Instruments.
Key Specifications
| Parameter | Description | Value |
|---|---|---|
| Package | SOIC (DW) | 16 pins |
| Operating Temperature Range | °C | -40 to 85 |
| Supply Voltage | V | 2.3 to 5.5 |
| I2C Bus Frequency | kHz | 100 (Standard-mode), 400 (Fast-mode) |
| Standby Current Consumption | µA | 1 max |
| Interrupt Output | Open-drain active-low | |
| Reset Input | Active-low | |
| I/O Port Configuration | Input or output selection via configuration register | |
| Polarity Inversion | Active HIGH or active LOW operation via Polarity Inversion register | |
| ESD Protection | 2000-V Human-body model, 200-V Machine model, 1000-V Charged-device model | |
| Latch-Up Performance | Exceeds 100 mA Per JESD 78, Class II |
Key Features
- Low standby current consumption of 1 µA max
- I2C to parallel port expander
- Open-drain active-low interrupt output
- Active-low reset input
- Operating power-supply voltage range of 2.3 V to 5.5 V
- 5-V tolerant I/O ports
- 400-kHz Fast I2C bus support
- Two hardware address pins (A0 and A1) allowing up to four devices on the same I2C/SMBus
- Input and output configuration register
- Polarity inversion register
- Power-up with all channels configured as inputs
- No glitch on power-up
- Noise filter on SCL/SDA inputs
- Latched outputs with high-current drive capability for directly driving LEDs
- ESD protection exceeds JESD 22 standards
Applications
The PCA9538PW is suitable for a variety of applications where additional I/Os are required, such as:
- ACPI power switches
- Sensors
- Push-buttons
- LEDs
- Fans
- Other general-purpose I/O expansion needs
Q & A
- What is the operating voltage range of the PCA9538PW?
The PCA9538PW operates within a power supply voltage range of 2.3 V to 5.5 V.
- What is the maximum standby current consumption of the PCA9538PW?
The maximum standby current consumption is 1 µA.
- What types of I2C bus frequencies does the PCA9538PW support?
The PCA9538PW supports both 100-kHz (Standard-mode) and 400-kHz (Fast-mode) I2C bus frequencies.
- How many devices can be connected on the same I2C/SMBus using the PCA9538PW?
Up to four devices can be connected on the same I2C/SMBus using the two hardware address pins (A0 and A1).
- What is the purpose of the interrupt output on the PCA9538PW?
The interrupt output is activated when any input state differs from its corresponding Input Port register state, indicating to the system master that an input state has changed.
- How does the PCA9538PW handle power-on reset?
The power-on reset sets the registers to their default values and initializes the device state machine. The RESET pin can also cause the same reset/initialization without de-powering the device.
- What is the ESD protection level of the PCA9538PW?
The PCA9538PW has ESD protection that exceeds JESD 22 standards, including 2000-V Human-body model, 200-V Machine model, and 1000-V Charged-device model.
- Can the PCA9538PW drive LEDs directly?
Yes, the latched outputs of the PCA9538PW have high-current drive capability for directly driving LEDs.
- What is the significance of the Polarity Inversion register in the PCA9538PW?
The Polarity Inversion register allows the polarity of the Input Port register to be inverted, enabling active HIGH or active LOW operation.
- Does the PCA9538PW have noise filtering on its inputs?
Yes, the PCA9538PW includes noise filters on the SCL/SDA inputs.
- How does the PCA9538PW handle latch-up performance?
The PCA9538PW's latch-up performance exceeds 100 mA Per JESD 78, Class II.
