PCA9538PW,118

I/o Expanders Overview

The PCA9538PW,118 is an 8-bit I2C-bus and SMBus low-power I/O port with interrupt and reset functionality. It operates within a supply voltage range of 2.3 V to 5.5 V and supports clock frequencies up to 400 kHz. The device provides eight general-purpose parallel input/output pins that default to inputs upon power-on reset. Key electrical characteristics include a typical operating supply current of 104 μA at 5.5 V and standby currents as low as 0.25 μA. It features open-drain interrupt output and active-low reset input, packaged in a TSSOP16 format.

I/o Expanders Feature Summary

• Provides 8-bit GPIO expansion with configurable input or output directions via configuration registers.
• Features an active-low interrupt output that activates when any input state differs from its corresponding register state.
• Includes an active-low reset input for initializing the device state machine without de-powering.
• Supports flexible polarity inversion for input data and includes noise filters on SCL/SDA inputs.

I/o Expanders Applications

• ACPI power switches
• Sensor interfaces
• Push-button detection
• LED control circuits

I/o Expanders Procurement Notes

Verify the specific ordering suffix '118' corresponds to the reel pack SMD version with a minimum order quantity of 2500 units. Confirm the ambient temperature rating aligns with standard commercial specifications (-40 °C to +85 °C) rather than automotive grades. Ensure compatibility with the required TSSOP16 package dimensions during PCB layout.

I/o Expanders Selection Notes

Select this component when additional I/O expansion is needed for I2C/SMBus systems requiring low standby current. It serves as a direct replacement for PCA9554 where internal pull-up resistors are not desired. Consider the 2.3 V minimum supply voltage for low-voltage applications. Verify address pin configurations (A0, A1) allow sufficient unique addresses on the bus.

I/o Expanders Part Context

The PCA9538 enhances the NXP Semiconductors family of I2C-bus I/O expanders by removing internal I/O pull-up resistors found in similar devices like the PCA9554. This modification significantly reduces power consumption when I/Os are held LOW. The device shares functional similarities with other 8-bit expanders but offers a distinct address range and dedicated RESET pin instead of an additional address pin.

I/o Expanders Replacement Considerations

PCA9554: Identical function but includes internal I/O pull-up resistors and lacks the dedicated RESET pin.

I/o Expanders FAQ

How does the PCA9538 differ from the PCA9554?

The PCA9538 removes the internal I/O pull-up resistor present in the PCA9554, which greatly reduces power consumption when I/Os are held LOW. Additionally, the PCA9538 replaces the A2 address pin with a RESET pin and has a different address range.

What happens to the I/O pins at power-on reset?

At power-on reset, all eight I/O pins are configured as inputs by default. The registers initialize to their default states, and the device state machine is initialized.

Can the PCA9538 be used with 5V tolerant signals?

Yes, the PCA9538 features 5 V tolerant I/Os, allowing input voltages up to 5.5 V even if the supply voltage (VDD) is lower.