ZSSC3122 Datasheet, PDF (16/64 Pages) List of Unclassifed Manufacturers – Low Voltage Capacitive Sensor Signal Conditioner

ZSSC3122
cLite™ Low Voltage Capacitive Sensor Signal Conditioner
capacitance C₀ is not exposed to DC voltages in order to prevent aging effects of some sensor types. The con-
figuration of the CDC is controlled by programming settings in EEPROM word C_Config. (See Table 5.3 for
settings.)
2.2.1.1. Single Ended
In the case of a single-sensor capacitor, the CDC output is proportional to the ratio of the sensor capacitor to an
internal reference capacitor (C_REF). This internal reference capacitor value can be adjusted using the 3-bit trim
CDC_Reference (bit settings in Table 5.3). To optimize the measured end-resolution further, another internal
capacitor (C_OFF) allows the subtraction of a defined offset capacitance using the 3-bit trim CDC_Offset (bit setting
in Table 5.3). Equations (1) to (2) describe the CDC output for a single sensor capacitance measurement. Select
the values of CDC_Offset, and CDC_Reference by using the tables in section 2.2.1.4.
Z _SENSOR

(C₀  C_OFF )
C_REF
(1)
Z _CDC  2 ^RES  Z _SENSOR
(2)
With
(3)
C_OFF  1.44  CDC _ Offset  1pF
And
C _REF  1.44  CDC _ Reference  1pF
(4)
Where:
Symbol
Z_SENSOR
C₀
C_OFF
C_REF
Z_CDC
RES
CDC_Offset
CDC_Reference
Description
Measured sensor ratio, must be in the range [0 to 1]
Input sensor capacitance
Zero shift of CDC
Reference capacitance
Digital raw converted capacitance value
Programmable CDC resolution of 8, 10, 12, or 14 bits (bit setting in Table 5.3)
CDC offset trim setting (selection see section 2.2.1.4 and bit setting see Table 5.3)
CDC reference setting (selection see section 2.2.1.4 and bit setting see Table 5.3)
Data Sheet
August 16, 2011
© 2011 Zentrum Mikroelektronik Dresden AG — Rev.1.20
All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used
without the prior written consent of the copyright owner. The information furnished in this publication is subject to changes
without notice.
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