TIC10024-Q1 Datasheet, PDF (31/81 Pages) Texas Instruments – 24-Input Multiple Switch Detection Interface (MSDI) Device With Adjustable Wetting Current for Automotive Systems

www.ti.com
TIC10024-Q1
SCPS268 – SEPTEMBER 2017
Device Functional Modes (continued)
Figure 21 illustrates the operation of the CCP when the device is configured to the continuous mode:
Wetting
current
TRIGGER bit set
to logic 1 in
CONFIG register
tSTARTUP
IN0
IN1
tCOMPt
IN2
IN22
IN23
ttPOLL_TIMEt
tSTARTUP
ttCCP_TIMEt
/INT
/CS
x Default input status is stored
x /INT pin is asserted after the
1^st detection cycle
Read on INT_STAT register
release the /INT pin
Time
Figure 21. Continue Mode With CCP Enabled
8.4.3.2 Wetting Current Auto-Scaling
The 10 mA and 15 mA wetting current settings are useful to clean oxide build-up on the mechanical switch
contact surface when the switch changes state from open to close. After the switch is closed, it is undesirable to
keep the wetting current level at high level if only digital switches are monitored since it results in high current
consumption and could potentially heat up the device quickly if multiple inputs are monitored. The wetting current
auto-scaling feature helps mitigate this issue.
When enabled (AUTO_SCALE_DIS_CSO or AUTO_SCALE_DIS_CSI bit = logic 0 in the WC_CFG1 register),
wetting current is reduced to 2 mA from 10 mA or 15 mA setting after switch closure is detected. The threshold
used to determine a switch closure is the threshold configured in the THRES_COMP register.
The current reduction takes place N cycles after switch closure is detected on an input, where N depends on the
setting of the DET_FILTER bits in the CONFIG register:
• DET_FILTER= 00: wetting current is reduced immediately in the next detection cycle after a closed switch is
detected.
• DET_FILTER= 01: wetting current is reduced when a closed switch is detected and the switch status is stable
for at least 2 consecutive detection cycles.
• DET_FILTER= 10: wetting current is reduced when a closed switch is detected and the switch status is stable
for at least 3 consecutive detection cycles.
• DET_FILTER= 11: wetting current is reduced when a closed switch is detected and the switch status is stable
for at least 4 consecutive detection cycles.
Copyright © 2017, Texas Instruments Incorporated
Product Folder Links: TIC10024-Q1
Submit Documentation Feedback
31