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

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ZMD31020

Sensor Signal Conditioner

Datasheet

Address locations &H07 and &H08 contain a low-side resp. high-side scale limit value for the corrected sensor

signal. Lower resp. -higher corrected signal values are clamped arithmetically to these limits by the CMC. Both

the low and high-side scale limits can be adjusted with a resolution of 12 bits. The 12 bit limit value must be

programmed into the least significant portion of either address. The 4 most significant bit locations of either

address are don't care bits and may be programmed freely.

Address locations &H0A and &H0B are available for customer-specific identification words, e.g. for traceability

purposes.

The contents of EEPROM addresses &H00 through &H09 are loaded into the RAM register block of the CMC

upon power-on. The configuration bits are routed from the configuration register to the various device functions

to be set up, see chapter 6.1.

Erasing and programming of the various EEPROM address locations during calibration requires programming

pulses of about 12V amplitude and about 10ms pulse width (see section 3.3.5). Further programming details are

to find in the ZMD31020 Functional Description.

Since a calibration is typically performed only once in a sensor's lifetime, no overhead chip-area for a charge-

pump has been spent. Thus the programming pulse has to be generated off-chip, and applied at the VPP

pin/pad. During normal operation mode the VPP pin/pad must be left open.

Note:

An on-chip switch short-circuits VPP to VDD in normal operation mode; the switch is opened to release

the VPP pin/pad for programming.)

In normal operation mode (regular sensing operation) the CMC runs a cyclic program which will output a

corrected 12-bit sensor value about every 10ms.

Within this cycle the CMC stages measurement of the ‚raw‘ sensor signal with 12 bits resolution, preceded by

measurement of temperature in 10 bits, and calculates a corrected sensor output value. Calculation is based on

a correction formula to which the 'raw' sensor signal and temperature as measured are applied in first and

second order terms - along with the 7 calibration parameters.

The measurement procedure of the 'raw' sensor signal and of temperature as well as the correction formula are

described in all details in the ZMD31020 Functional description

The 2-wire I

2.9.1

Digital Corrected Sensor Signal Output and I/O for Calibration and Device Test

During normal operation mode (regular sensing operation) the I

signal (12 bits) digitally and serially. During calibration the interface is input for the configuration word, output for

the 'raw' non-corrected sensor signal as well as for temperature, and finally again input for the calculated

calibration parameters as well as the scale limit values and possibly customer-specific identifiers. As a third

option, the interface is used to input digital vectors during device test, e.g. to exercise the output DAC, see

section 2.10.

2.9.2

Data Communication Specifics

An I

START and STOP conditions. ZMD31020 is designed to work as a slave - thus it will only respond to requests

from a master device. Obviously a typical master device during regular sensing operation is a connected

electronic controller unit requesting sensor data. (During calibration a connected PC or computer will be the

master. During device test the ATE system will be the master.)

2.8

Sensor Signal Correction Method and Sequence

2.9

Digital I