Switch-status monitors reduce footprint of system interface

Freescale has introduced a family of multiple-input switch-detection interface ICs that detect the opening and closing of up to 22 switch contacts.

These devices replace several discrete components when interfacing to microprocessor-based systems, and provide ground-offset protection, wetting current for the switch contacts, and system wake-up signals.

The MCZ33993EW, MCZ33972EW and MCZ33975EK have eight programmable sense inputs capable of verifying a connection to ground or to the battery voltage level, and 14 additional programmable inputs to verify connection to ground only. All three devices transfer the switch status, either open or closed, to a host MCU through an SPI Interface.

The MCZ33993EW, draws 100µA of stand-by current from the battery input, and provides selectable wetting current of 16mA or 2mA. In addition, programmable wake-up and interrupt functions support flexibility and low-power operation.

The MCZ33972EW gives designers the extra option of a suppressed-wake-up function, while the MCZ33975EK also provides higher wetting current of 4mA or 32mA. The MCZ33975EK features a programmable interrupt timer for the sleep mode, which can be disabled, and an interrupt bit that can be reset.

 

FEATURES Battery input voltage range: 5.5V to 26V Selectable wake-up on change-of-state Active interrupt on change-of-state Over-temperature shutdown with hysteretic recovery 32-pin wide-body SOIC (SOIC-W) package

APPLICATIONS Automotive sensing and control Computer systems Telecommunications Industrial controls

 

 

www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MC33972&fsrch=1