MC33975A 데이터 시트보기 (PDF) - Freescale Semiconductor

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MC33975A

Multiple Switch Detection Interface with Suppressed Wake-up and 32 mA Wetting Current

Freescale Semiconductor 

FUNCTIONAL DESCRIPTIONS

FUNCTIONAL INTERNAL BLOCK DESCRIPTION

FUNCTIONAL INTERNAL BLOCK DESCRIPTION

MC33975 - Functional Block Diagram

Analog Control

and Protection Circuitry

Bandgap

Voltage Regulation

Temp. Sense

Oscillator & Clock

Programmable

Monitor Inputs

SP0 - SP7

MCU Interface and Control

Interrupt/Wake-up

SPI Interface

Multiplex Control

Monitor Inputs

SG0 - SG13

Control & Protection Interface & Control Prog. Monitor Monitor

Figure 7. Functional Internal Block Description

ANALOG CONTROL AND PROTECTION

CIRCUITRY:

The 33975 is designed to operate from 5.5 V to 38/40 V on

the VPWR pin. Characteristics are provided from 8.0 to 28 V

for the device. Switch contact currents and the internal logic

supply are generated from the VPWR pin. The VDD supply

pin is used to set the SPI communication voltage levels,

current source for the SO driver, and pull-up current on INT

and CS.

The on-chip voltage regulator and bandgap supplies the

required voltages to the internal monitor circuitry. The

temperature monitor is active in the Normal Mode.

MCU INTERFACE AND CONTROL:

The 33975 Multiple Switch Detection Interface with

Suppressed Wake-up is designed to detect the closing and

opening of up to 22 switch contacts. The switch status, either

open or closed, is transferred to the microprocessor unit

(MCU) through a serial peripheral interface (SPI).

The device also features a 22-to-1 analog multiplexer for

reading inputs as analog. The 33975 device has two modes

of operation, Normal and Sleep.

SWITCH PROGRAMMABLE INPUTS:

Programmable switch detection inputs. These 8 inputs can

selectively detect switch closures to ground or battery. The

33975 device has 8 switch inputs capable of being

programmed to read switch-to-ground or switch-to-battery

contacts. The input is compared with a 4.0 V reference.

When programmed to be switch-to-battery, voltages greater

than 4.0 V are considered closed. Voltages less than 4.0 V

are considered open. The opposite holds true when inputs

are programmed as switch-to-ground.

SWITCH–TO-GROUND INPUTS:

Switch detection interface inputs. These 14 inputs can detect

switch closures to ground only. The input is compared with a

4.0 V reference. Voltages greater than 4.0 V are considered

open. Voltages less than 4.0 V are considered closed. Note:

Each of these inputs may be used to supply current to

sensors external to a module.

33975

14

Analog Integrated Circuit Device Data

Freescale Semiconductor

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