QST108 STMicroelectronics, QST108 Datasheet - Page 16

• Manufacturer Part Number: QST108
• Description: Capacitive Touch Sensor Device 8 Keys With Individual Key State Outputs Or I2c Interface
• Manufacturer: STMicroelectronics

Device operating modes
4.5.3
Note:
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Option descriptions
Adjacent key suppression (AKS™)
The QST108 features an adjacent key suppression (AKS™) function.
This function is enabled using the AKS option resistor (OPT2) in standard output mode as
described in
of the option resistor configuration.
Table 4.
Low Power mode option
This option resistor (OPT3) selects whether the device is always sensing the keys or if a low
power consumption phase is introduced between bursts as described in
In Low Power mode, a very low consumption (sleep) phase of 100ms is inserted between
the Group B burst and the Group A burst. This significantly reduces the overall consumption
of the device. Sleep duration is not accurate and can vary substantially depending on V
and temperature values.
In Low Power mode, the response time is increased.
Table 5.
Max On-Duration
There are four recalibration timing options (“Max On-Duration”). The recalibration option
resistors (OPT4 and OPT5) control how long it takes for a continuous detection to trigger a
recalibration on a key as described in
key is recalibrated.
Table 6.
OPT4/MOD_0 OPT5/MOD_1
V
V
V
V
OPT2/AKS
DD
DD
SS
SS
OPT3/LP
V
V
V
V
DD
DD
SS
SS
AKS truth table
Low power (LP) mode truth table
Max On-Duration (MOD) truth table
Table
4. In BCD output mode, the AKS function is always enabled, regardless
V
V
V
V
DD
DD
SS
SS
Disabled
Global locking AKS on all available keys
Free running mode
100ms sleep duration
Infinite
60s
20s
10s
Table
6. When such an event occurs, only the “stuck”
Description
Description
Description
Table
5.
QST108
DD