General-purpose I/Os
ROYAL Philips Electronics has released a series of I2C-bus-controlled, push-pull, general purpose Input/Outputs (GPIOs). They reduce power consumption to extend the battery life of mobile devices.
They have an interrupt output and a reset input. This enables the I2C-bus to be quickly reset, which is especially important for high-reliability applications such as servers where a hang up of the I2C-bus could cause failure of the system.
Removing the internal pull-up resistor in existing Philips' GPIOs allows designers to add additional GPIOs into battery powered systems while minimising the current consumption, thus sustaining battery life. Some of these devices have both an interrupt output pin and hardware reset input pin. This allows server manufacturers to recover the I2C-bus without the need to cycle power, enabling positive control of the bus and removing the need to restart the server when errors occur. The reset pin offers the software programmers an easy way to simplify the programming sequence by resetting all registers using the external reset pin.
The four, eight and 16-bit devices have similar footprints to Philips' existing I2C GPIOs, enabling easy migration for applications where totem pole outputs are required but without internal pull up resistors.
The PCA9534 and PCA9535, both with interrupt outputs, are designed for mobile applications where low power consumption is required. The PCA9536 is an inexpensive four-bit GPIO, the only new device that includes internal pull up resistors in an eight-pin package. The PCA9537, PCA9538 and PCA9539 are four, eight and 16-bit GPIOs respectively, and feature both an interrupt output and reset input.
6-Dec-2004