PCA6408A Datasheet | NXP Semiconductors

description The PCA6408A is an 8-bit general purpose I/O expander that provides remote I/O expansion for most microcontroller families via the I2C-bus interface. NXP I/O expanders provide a simple solution when additional I/Os are needed while keeping interconnections to a minimum, for example, in battery-powered mobile applications for interfacing to sensors, push buttons, keypad, etc. In addition to providing a flexible set of GPIOs, it simplifies interconnection of a processor running at one voltage level to I/O devices operating at a different (usually higher) voltage level. The PCA6408A has built-in level shifting feature that makes these devices extremely flexible in mixed signal environments where munication between inpatible I/O voltages is required. Its wide VDD range of 1.65 V to 5.5 V on the dual power rail allows seamless munications with next-generation low voltage microprocessors and microcontrollers on the interface side (SDA/SCL) and peripherals at a higher voltage on the port side. There are two supply voltages for PCA6408A: VDD(I2C-bus) and VDD(P). VDD(I2C-bus) provides the supply voltage for the interface at the master side (for example, a microcontroller) and the VDD(P) provides the supply for core circuits and Port P. The bidirectional voltage level translation in the PCA6408A is provided through VDD(I2C-bus). VDD(I2C-bus) should be connected to the VDD of the external SCL/SDA lines. This indicates the VDD level of the I2C-bus to the PCA6408A. The voltage level on Port P of the PCA6408A is determined by the VDD(P). The PCA6408A consists of one 8-bit Configuration (input or output selection), Input, Output, and Polarity Inversion (active HIGH) register. At power-on, the I/Os are configured as inputs. 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...