Copyright © 2004, ZMD AG, Rev. 1.6, 2005-05-19

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ZMD31020

Sensor Signal Conditioner

Datasheet

2.

CIRCUIT DESCRIPTION

Block diagram of ZMD31050

PGA

programmable gain amplifier

MUX

multiplexer

ADC

analog-to-digital converter

CMC

calibration microcontroller

DAC

digital-to-analog converter

BAMP

buffer amplifier

TS

on-chip temperature sensor (pn-junction)

EEPROM

for calibration parameters and configuration

ROM

for correction formula and –algorithm

I

serial interface: I

2

C data I/O, clock

The ZMD31020’s signal path is partly analog (blue) and partly digital (red). The differential signal from the

resistive bridge sensor is pre-amplified by the programmable gain amplifier (PGA). There are 3 different

adjustable gains.

The Multiplexer (MUX) transmits the differential signal or the temperature signal to the ADC in a certain

sequence. (The external temperature sensing diode or the internal temperature sensor can be used optionally.)

The ADC converts the differential signal with 12 bits resolution and the temperature signal with 10 bits resolution

into digital values.

2.1 Signal Flow