TCA7408ZSZR

Overview

The TCA7408 is an 8-bit I/O expander for the two-line bidirectional bus (I2C) designed to provide general-purpose remote I/O expansion. It operates with a VCCI supply range of 1.65 V to 5.5 V and a VCCP supply range of 1.65 V to 3.6 V, enabling bidirectional voltage-level translation between different logic levels. The device supports standard mode (100 kHz) and fast mode (400 kHz) clock frequencies. It features an active-low reset input, an open-drain active-low interrupt output, and programmable pull-up/pull-down resistors for GPIO inputs.

Feature Summary

• Bidirectional voltage-level translation capability between 1.8-V, 2.5-V, 3.3-V, and 5-V SCL/SDA lines and 1.8-V, 2.5-V, or 3.3-V GPIO ports.
• Integrated watchdog timer that resets the I2C state machine if the SDA line is held low internally for approximately 200 ms.
• Programmable edge detection for generating interrupts on GPIO port transitions, with interrupt masking and latching capabilities.

Applications

• Personal electronics such as smartphones, gaming consoles, and personal computers
• Servers, routers, telecom switching equipment, and industrial automation systems
• Products utilizing processors with limited general-purpose input/output pins

Procurement Notes

Verify the specific ordering suffix ZSZ corresponds to the µCSP 16-ball package (4 x 4 mm) when sourcing components. Confirm RoHS compliance status and check for any recent production data revisions that may affect availability or documentation references. Ensure the supplier provides valid traceability documents for quality assurance purposes.

Selection Notes

Select this component when interfacing microprocessors with varying supply voltages, specifically where the host operates at up to 5.5 V while the peripheral GPIOs require lower voltages down to 1.65 V. Consider the device for designs requiring hardware reset functionality and interrupt-driven input monitoring without continuous polling overhead on the I2C bus.

Part Context

The TCA7408 belongs to Texas Instruments' family of I2C and SMBus I/O expanders. It shares functional similarities with other devices in the series but is distinguished by its wide operating voltage range and integrated watchdog timer. This specific model targets applications needing robust voltage translation and reliable state management in space-constrained environments.

Replacement Considerations

Consult official TI documentation for direct pin-to-pin replacements. Verify compatibility regarding supply voltage ranges, package dimensions, and register maps before substituting with alternative part numbers from the same manufacturer or other vendors.

FAQ

How does the TCA7408 handle voltage level translation?

The device uses separate supply pins, VCCI for the I2C bus side (up to 5.5 V) and VCCP for the GPIO port side (up to 3.6 V), allowing bidirectional translation between these distinct voltage domains.

What triggers the internal watchdog timer reset?

The watchdog timer resets the I2C state machine if the SDA line is internally held low for a nominal duration of 200 ms, preventing system lockups without resetting the GPIO registers.

Can multiple TCA7408 devices share the same I2C bus?

Yes, up to two devices can share the same bus by configuring the ADDR pin to either ground or VCCI, which sets the last three bits of the slave address to either 011 or 100 respectively.