IS31SE5117 EVB User Manual
Lumissil Microsystems – www.lumissil.com
24
Rev. B, 10/25/2020
Figure 35: AUTO_SLEEP_SET option
6.9
SCAN_SETTING
：
Scan And Frequency Setting
Scanning function is set as shown in Figure 36,
Figure 36: SCAN_SETTING option
REFSEL is VREF selection (Use 1.8V or VDDH as a reference).
REF CAPACITOR CHARGING VOL TH is set the reference capacitor charging voltage.
Improve Vth will increase detecting time and sensitivity, but might interfere SNR.
REF CAPACITOR DISCHARGE VOL TO 0 TIME SET is set the reset time for reference capacitor discharging.
The reference capacitor should be reset before each detecting period and increase discharging time by actual
application.
Scanning frequency is set as shown in Figure 37,
Figure 37: SCANNING_FREQUENCY_SET option
FIRST SCAN FRE SET is the first scanning frequency setting;
SECOND SCAN FRE SET is the second scanning frequency setting;
THIRD SCAN FRE SET is the third scanning frequency setting;
FOURTH SCAN FRE SET is the fourth scanning frequency setting.
A higher scanning frequency will decrease detecting time and not sensitive for alternating supply ripple,
precondition is the sensing pad charged enough to VREF or the sensitive will get worse.
These four scanning frequencies are plus total to evaluate the effect.
KEYx Value
NEG_DELTA_TH
N__CAL_NEG_TH
NEG_DELTA_CNT
Value = 0
1
2
3
When negative detect times are over
NEG_DELTA_CNT, channel will be
calibrated
When negative value is over
N_CAL_NEG_TH, channel will be
calibrated
n
