1 lc-sensor oscillation test – Texas Instruments MSP430x4xx User Manual

Page 489

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Scan IF Operation

24-29

Scan IF

24.2.6.1 LC-Sensor Oscillation Test

The oscillation test tests if the amplitude of the oscillation after sensor
excitation is above a reference level. The DAC is used to set the reference
level for the comparator, and the comparator detects if the LC sensor
oscillations are above or below the reference level. If the oscillations are above
the reference level, the comparator will output a pulse train corresponding to
the oscillations and the selected AFE output bit will 1. The measurement timing
and reference level depend on the sensors and the system and should be
chosen such that the difference between the damped and the un-damped
amplitude is maximized. Figure 24−15 shows the connections for the
oscillation test.

Figure 24−15. LC Sensor Connections For The Oscillation Test

Power
Supply
Terminals

SIFCI0

SIFCI

SIFCI1

SIFCI2

SIFCI3

470nF

AV

CC

DV

CC

DV

SS

AV

SS

SIFVSS

470 nF

SIFCOM

SIFCH1

SIFCH0

SIFCH2

SIFCH3

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