SCPS128D July 2006 – March 2021 PCA9554
This 8-bit I/O expander for the two-line bidirectional bus (I2C) is designed for 2.3-V to 5.5-V VCC operation. It provides general-purpose remote I/O expansion for most microcontroller families via the I2C interface [serial clock (SCL), serial data (SDA)].
The PCA9554 consists of one 8-bit Configuration (input or output selection), Input, Output, and Polarity Inversion (active high or active low) registers. At power on, the I/Os are configured as inputs with a weak pullup to VCC. However, the system master can enable the I/Os as either inputs or outputs by writing to the I/O configuration bits. The data for each input or output is kept in the corresponding Input or Output register. The polarity of the Input Port register can be inverted with the Polarity Inversion register. All registers can be read by the system master.
The system master can reset the PCA9554 in the event of a timeout or other improper operation by utilizing the power-on reset feature, which puts the registers in their default state and initializes the I2C/SMBus state machine.
The PCA9554 open-drain interrupt ( INT) output is activated when any input state differs from its corresponding Input Port register state and is used to indicate to the system master that an input state has changed.
|PART NUMBER||PACKAGE||BODY SIZE (NOM)|
|PCA9554||SSOP (16)||6.20 mm × 5.30 mm|
|VQFN (16)||4.00 mm × 4.00 mm|
|QFN (16)||3.00 mm × 3.00 mm|