TCA9554DBR
TCA9554DBR - 8-Bit I/O Expander, 1.65-5.5V, SSOP-16 | Texas Instruments
The Texas Instruments TCA9554DBR is an 8-bit I2C/SMBus I/O expander designed for low-voltage embedded systems, operating from 1.65 V to 5.5 V and supporting both 100 kHz Standard-mode and 400 kHz Fast-mode serial operation. The device provides eight configurable parallel input/output ports, an interrupt output, and hardware-selectable addresses through A0, A1, and A2 pins in a 16-pin SSOP package.
An I/O expander is a semiconductor interface device that adds parallel digital input and output capability to a host controller without requiring additional direct GPIO pins. The TCA9554 sits within the I2C interface hierarchy: host controller, I2C/SMBus bus, I/O expander, and individual digital input/output channels. This makes it useful for reducing connector count, extending control capability, and centralizing control of peripherals such as LEDs, buttons, relays, and sensors.
The principal features include 8 configurable I/O pins, interrupt generation when an input state changes, weak pull-up capability, configuration registers, and support for up to eight devices on the same bus using the three hardware address inputs. According to the Texas Instruments product description, the TCA9554 is intended for low-voltage, low-power peripheral expansion and can be reset to its default state through power-on reset.
The TCA9554DBR uses a serial register-oriented control interface. The host writes to configuration registers to select input or output operation and reads the input port register to determine the state of external logic. The interrupt output provides a way for the host to respond to input changes without continuously polling the I2C bus. Its 1.65 V to 5.5 V operating range supports both low-voltage digital systems and conventional 5 V peripheral environments, while the 400 kHz bus capability improves update rate for larger control tasks.
Typical uses include industrial control panels, consumer appliances, battery-powered equipment, LED status boards, keyboard and button interfaces, sensor aggregation, and compact embedded systems where the primary microcontroller has insufficient GPIO pins. Because the I/O ports operate from the device supply voltage, logic levels must remain compatible with the connected host and external circuits.
PCB layout should keep the I2C bus traces short, provide the pull-up arrangement required by the system, and route the interrupt signal away from high-current switching paths. The SSOP-16 package requires careful soldering and adequate clearance around adjacent components. Designers should also confirm the operating voltage, address configuration, pull-up strength, and interrupt polarity against the application requirements before releasing the PCB.
This product page combines manufacturer specifications, package information, application guidance, comparison context, and practical design notes to support component selection and implementation of the TCA9554DBR.
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