AD7143 Analog Devices, AD7143 Datasheet - Page 18

• Manufacturer Part Number: AD7143
• Description: Programmable Controller for Capacitance Touch Sensors
• Manufacturer: Analog Devices

Specifications of AD7143

• Resolution (bits): 16bit
• # Chan: 8
• Sample Rate: n/a
• Interface: I²C/Ser 2-Wire,Ser
• Analog Input Type: n/a
• Ain Range: ± 2 pF (Delta C)
• Adc Architecture: Sigma-Delta
• Pkg Type: CSP

AD7143
Note that in Figure 29, the sequence conversion time, t
CDC CONVERSION
RECALIBRATION
CALIBRATION
DETECTION
(INTERNAL)
(INTERNAL)
(INTERNAL)
SEQUENCE
PROXIMITY
(INTERNAL)
COUNTER
Figure 29. Full Power Mode Proximity Detection with Forced Recalibration Example with FP_PROXIMIT_CNT = 1 and FP_PROXIMITY_RECAL = 40
CDC CONVERSION
CDC CONVERSION
CALIBRATION
CALIBRATION
DETECTION
DETECTION
(INTERNAL)
(INTERNAL)
(INTERNAL)
(INTERNAL)
(INTERNAL)
(INTERNAL)
SEQUENCE
SEQUENCE
PROXIMITY
PROXIMITY
NOTES
1.
2.
3.
t
t
t
CALDIS
RECAL_TIMEOUT
RECAL
USER APPROACHES
SENSOR HERE
= 2 ×
=
Figure 28. Low Power Mode Proximity Detection with LP_PROXIMITY_CNT = 4 and LP_CONV_DELAY = 0
NOTES
1. SEQUENCE CONVERSION TIME
2. PROXIMITY IS SET WHEN USER APPROACHES THE SENSOR AT WHICH TIME THE INTERNAL CALIBRATION IS DISABLED.
3.
t
CONV_FP
t
CALDIS
t
CONV_FP
USER APPROACHES
USER APPROACHES
=
SENSOR HERE
SENSOR HERE
t
USER LEAVES SENSOR
Figure 27. Full Power Mode Proximity Detection Example with FP_PROXIMITY_CNT = 1
CONV_FP
× FP_PROXIMITY_CNT × 16.
= (
CALIBRATION DISABLED
.
t
CONV_LP
AREA HERE
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
× FP_PROXIMITY_RECAL.
× LP_PROXIMITY_CNT × 4).
16
USER LEAVES SENSOR
USER LEAVES SENSOR
t
CALDIS
AREA HERE
AREA HERE
t
CONV_LP
CONV_FP,
CALIBRATION DISABLED
CALIBRATION DISABLED
=
Rev. 0 | Page 18 of 56
t
CONV_FP
is determined from Table 8.
30
MEASURED CDC VALUE > STORED AMBIENT
+ LP_CONV_DELAY.
BY PROXIMITY_RECAL _LVL
RECALIBRATION TIMEOUT
t
t
CALDIS
CALDIS
17 18 19 20 21 22 23 24
17 18 19 20 21 22 23 24
t
RECAL_TIMEOUT
CALIBRATION ENABLED
CALIBRATION ENABLED
t
RECAL
70
CALIBRATION ENABLED
t
t
CONV_FP
CONV_LP
t
CONV_FP