San Jose, Calif. Royal Philips Electronics introduced a series of I²C-bus controlled push-pull general-purpose input/outputs (GPIOs) that tout reduced power consumption for portable applications, as well as interrupt output and reset input functions.
In applications like mobile phones and PDAs, there is often a need for more GPIOs other than what's already integrated into the processor, said Pierre-Yves Lesaicherre, general manager, interface products business line at Philips Semiconductors. Removing the internal pull-up resistor in existing Philips' GPIOs allows designers to add additional GPIOs into battery powered systems, while minimizing current consumption and enabling sustained battery life, he said.
“Removing the internal pull-up resistors is just an optimized way of reducing power, which no one else is doing right now,” said Pierre-Yves Lesaicherre, general manager, interface products business line at Philips Semiconductors. “Philips' previous generation 8-bit GPIOs offered power consumption of 550μA. With the removal of the internal pull up resistors, the new 8-bit device (PCA9534) provides power consumption of 0.25μA. The reduction is approximately 2200 times in power consumption,” he said.
Some cell phone and PDA makers were reluctant to use Philips' earlier generation GPIOs because of high power consumption. With this new feature added, however, the company has seen a demand surge for these devices in battery powered applications, Lesaicherre said.
Another unique feature about Philips' I²C GPIOs is that the devices contain both an interrupt output and reset input. This enables the I²C-bus to 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, Lesaicherre said.
Consequently, server manufacturers such as IBM Corp. (Armonk, N.Y.) can recover the I²C-bus without the need to cycle power, enabling positive control of the bus and negating the need to restart the server when errors occur, Lesaicherre said. “The external reset pin offers the software programmers an easy way to simplify the programming sequence by simply resetting all registers,” he said.
“Philips' new PCA9538/9539 I/O expanders integrate push pull outputs, interrupt and hardware reset all the functions we need for reliable server operation into a single package,” said Bob Christopher, senior engineer, advanced server technology development, IBM Corp. “This enables us to reduce real estate and lower our component count. The parts maintain a software interface consistent with that of PCA9554/9555 so that, aside from an address change, existing code need not change.”
The new 4-, 8- and 16-bit devices have similar footprints to Philips' existing PCA9554554/54A/55/56/57 I²C GPIOs, for 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 4-bit GPIO, the only new device that includes internal pull up resistors, in a very small 8-pin package. The PCA9537, PCA9538 and PCA9539 are 4-, 8- and 16-bit GPIOs, respectively, and feature both an interrupt output and reset input.
Products in the PCA953x GPIO family are offered in SO, TSSOP and HVQFN packages. The 8-bit PCA9534 and PCA9538 are available in 16-pin SO, TSSOP and HVQFN, priced at 90 cents in 10,000-piece quantities. The 16-bit PCA9535 and PCA9539 are available in 24-pin SO, TSSOP and HVQFN and priced at $1.30 in same quantities. The 4-bit PCA9536 and PCA9537 are available in 8-pin and 10-pin 3mm x 3mm TSSOP (MSOP), respectively, and are both priced at 55 cents. All devices are available in volume except the PCA9536 and PCA9537, which are currently sampling. Volume production is expected by year-end.
For more information, please call 1-800-447-1500 or visit: www.semiconductors.philips.com.