ZSSC3122 Datasheet, PDF (51/64 Pages) List of Unclassifed Manufacturers – Low Voltage Capacitive Sensor Signal Conditioner

ZSSC3122 Datasheet
6 Calibration and Signal Conditioning Math
IDT can provide software and hardware with samples to perform the calibration. For a complete description and
detailed examples, see the ZSSC3122/ZSSC3123_SSC_Modular_Evaluation_Kit_Description_RevX_xy.pdf. For
more details on the following equations, refer to ZSSC3122 Technical Note—Detailed Equations for ZSSC3122
Rev C Silicon Math (available on request).
Note For best results the calibration should be done with all settings set to the final application including supply
voltage, measurement mode, update rate, output mode, resolution, and AFE settings in the final packaging.
6.1 Capacitance Signal Conditioning
The ZSSC3122 supports up to a two-region piece-wise, non-linear sensor input or a third-order correction
selectable. The general form of the capacitance signal conditioning equation is provided below.
Note: The following equations are only meant to show the general form and capabilities of the ZSSC3122 sensor
signal conditioning.
Two-region piece-wise, non-linear sensor input
RawTC = ^{Raw _ C + OFFSET + ∆T ∗( Tco + ∆T ∗ SOT _ tco )}
(17)
1 + ∆T ∗( Tcg + ∆T ∗ SOT _ tcg )
Raw₁ = MIN( RawTC,Raw _ Break )
(18)
Raw₂ = MAX ( 0,RawTC − Raw _ Break )
(19)
Out = SOT _ 1* ( Gain _ 1* Raw₁ )² + Gain _ 1* Raw₁
(20)
+ SOT _ 2* ( Gain _ 2* Raw₂ )² + Gain _ 2* Raw₂
Or alternatively
Non-linear sensor input up to third-order correction
Raw₁
=
Raw _ C
+ OFFSET + ∆T ∗ (Tco + ∆T ∗ SOT
1 + ∆T ∗ (Tcg + ∆T ∗ SOT _ tcg)
_ tco)
(21)
Out = TOT _1* (Gain _1* Raw₁)³ + SOT _1* (Gain _1* Raw₁)² + Gain _1* Raw₁
(22)
Where:
Symbol
© 2016 Integrated Device Technology, Inc.
Description
51
January 25, 2016