Overview: MOTOROLA SEMICONDUCTOR TECHNICAL DATA Freescale Semiconductor, Inc. Order this document by MC33884/D Advance Information Switch Monitor Interface
The MC33884 Switch Monitor Interface is a monolithic silicon integrated circuit (IC) that performs switch monitoring functions. The device provides efficient interface between electrical switches and low voltage microprocessors. The MC33884 supplies switch contact pull–up and pull–down current while monitoring the input voltage level. All inputs are protected for transients when implemented with an appropriate static discharge capacitor used on the inputs. There are four modes of operation – Sleep, Normal, Polling, and Polling + INT Timer. Sleep mode reduces the current drain to a quiescent current level of 10 m A and disables the IC. Normal mode interrupts the microprocessor whenever any external switch changes it’s OPEN or CLOSED state. Polling mode reads a switch status periodically and interrupts the microprocessor only when an external switch is sensed as being CLOSED. The Polling + INT Timer mode is similar to the Polling mode, with the addition of an interrupt being sent to the microprocessor if a switch is sensed CLOSED or upon the internal interrupt timer ”timing out”. An interrupt is always ultimately sent to the microprocessor in this mode. All modes of operation are easily programmed via the Serial Peripheral Interface (SPI) control.
