ZSC31150

Fast Automotive Sensor Signal Conditioner

Data Sheet

August 31, 2010

© 2010 Zentrum Mikroelektronik Dresden AG — Rev. 1.07

All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without

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notice.

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2.3.2.

Offset Compensation

The ZSC31150 supports two methods of sensor offset compensation (zero shift):



Digital offset correction



XZC - Analog compensation for large offset values (up to in maximum approximately 300% of span,

depending on gain adjustment)

Digital sensor offset correction will be processed during the digital signal correction/conditioning by the

calibration microcontroller (CMC). Analog sensor offset pre-compensation will be needed for compensation of

large offset values, which would overdrive the analog signal path by uncompensated gaining. For analog

sensor offset pre-compensation, a compensation voltage will be added in the analog pre-gaining signal path

(coarse offset removal). The analog offset compensation in the AFE can be adjusted by 6 EEPROM bits.

Table 2.2

Analog Zero Point Shift Ranges (XZC)

PGA gain

aIN

Max. Span VIN_SP

[mV/V]

Offset shift per step

in % of full span

Approx. maximum

offset shift [mV/V]

Approx. maximum shift

[% VIN_SP] (@ ± 31)

420

1.8

12.5 %

7.8

388 %

280

2.7

7.6 %

7.1

237 %

210

3.6

12.5 %

15.5

388 %

140

5.4

7.6 %

14.2

237 %

105

7.1

12,5 %

31

388 %

70

10.7

7.6 %

28

237 %

52.5

14.3

12,5 %

32

388 %

35

21.4

7.6 %

57

237 %

26.3

28.5

5.2 %

52

161 %

14

53.75

12.5 %

194

388 %

9.3

80

7.6 %

189

237 %

7

107

5.2 %

161

161 %

2.8

267

0.83 %

72

26 %

2.3.3.

Measurement Cycle

The Multiplexer selects, depending on EEPROM settings, the following inputs in a certain sequence.



Temperature measured by external diode or thermistor, internal pn-junction or bridge



Internal offset of the input channel (VOFF)



Pre-amplified bridge sensor signal

The complete measurement cycle is controlled by the CMC. The cycle diagram at Figure 2.2 shows its

principle structure.

The EEPROM adjustable parameters are:



n=<1,31>: Pressure measurement count

After power on the start routine is called, that contains all needed measurements once.

Remark:

The tasks “CMV”, “SSC/SCC+” and “SSC/SCC-“ are contained independent from EEPROM

configuration always in every cycle.