News and New Products

8-bit I²C bus expander has low standby current

By Paul Rako, Technical Editor -- EDN, 6/9/2008

Catalyst Semiconductor has developed an 8-bit I/O expander that connects to a system through an I²C serial bus. The 8-bit, general-purpose CAT9534 GPIO (general-purpose input/output) expander for I²C and SMBus-based systems is pin-for-pin compatible with the industry-standard CAT9554 but uses 100 times less standby power, consuming only 1μA maximum. The eight ports power up as inputs, and you can then configure them as outputs by writing to an internal register. The device features an external power-on-reset feature to eliminate any glitches on power-up. Each port can sink 25 mA and source 10 mA. When you configure the ports as inputs, they are compatible with 2.5, 3.3, and 5V logic levels. The CAT9534 operates on 2.3 to 5.5V and is compatible with 400-kHz I²C-bus architectures.

The CAT9534 is available in a 16-pin SOIC, TSSOP, and 4×4-mm TQFN packages for a suggested retail price of 83 cents (10,000). The IC operates across a −40 to +85°C temperature range. Samples are available now, and production quantities require a six- to eight-week leadtime.