TCA9538DBR
TCA9538DBR - 8-Bit I2C I/O Expander | Texas Instruments
Texas Instruments TCA9538DBR is an 8-bit I2C/SMBus low-power I/O expander with a 1.65 V to 5.5 V operating range, 400 kHz bus speed, and a 16-pin SSOP package. It adds eight general-purpose input or output ports through a two-wire serial interface while providing interrupt, reset, and configuration registers. The device is intended for systems in which a host controller needs more parallel I/O than its native package or connector resources can provide.
An I/O expander is an interface IC that extends the number of digital input and output pins available to a host processor. The TCA9538 belongs to the I2C interface hierarchy, where the I2C or SMBus protocol links the expander to a controller such as a microcontroller. Each port can be configured as an input or output, allowing the same circuit to support switches, sensors, logic-control signals, LEDs, and other digital peripherals while conserving host pins and reducing interconnect complexity.
The principal operating parameters are an 8-bit port count, a 1.65 V minimum supply voltage, a 5.5 V maximum supply voltage, and support for a 400 kHz I2C bus. According to the Texas Instruments product page, the device also includes an interrupt output, reset control, and configuration registers. These functions support event-driven peripheral monitoring and orderly control of multiple downstream signals without continuous polling by the host processor.
The TCA9538DBR is a remote, low-power parallel-interface device rather than a general-purpose processor or transceiver. Its serial control path uses the two-wire I2C or SMBus interface, while the eight parallel ports connect to digital circuitry in the target system. The SSOP-16 package provides a compact surface-mount format, and the manufacturer lists the part as active. Its operating temperature range is -40 °C to +85 °C, supporting industrial-temperature equipment when correctly handled for thermal and soldering requirements.
Typical uses include control-panel backlights, sensor and switch interfaces, relay-control inputs, programmable logic interfaces, battery-powered monitoring equipment, and communication equipment requiring additional GPIO. The TCA9538 is especially useful when the host controller has limited spare pins but the system still needs eight independently configurable digital lines and an interrupt mechanism for status changes.
Design the bus with pull-up resistors appropriate for the operating voltage, confirm that the 400 kHz bus rate is compatible with the complete bus capacitance and every attached peripheral, and account for logic thresholds when the expander operates alongside mixed-voltage devices. Place the interface pins, supply decoupling, and pull-up network to minimize routing delay and maintain signal integrity across the board.
This product record combines the manufacturer’s electrical and package information with practical interface-selection guidance, pinout-location references, application analysis, and compatibility cautions. It also distinguishes true same-package drop-in replacements from related expanders that differ in footprint, voltage tolerance, interrupt behavior, or register implementation and therefore require engineering review before substitution.
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