BU21079F Datasheet, PDF (24/37 Pages) Rohm – Capacitive Switch Controller ICs

BU21079F
Datasheet
Operational mode
This IC has three operational modes, [Stop mode], [Intermittent mode], and [Normal mode].
【Stop mode】
It is the state where detection is disabled.
Detection is stopped by setting '0' to ACT of the sensor motion control register CNT (address 0xFF).
A detection process is stopped and consumption current decreases by performing the power down of AFE.
【Normal mode】
In normal mode, detection is continuous.
Sensing is started by setting '1' to ACT of the sensor motion control register CNT (address 0xFF).
Starting detection and soft calibration is operated simultaneously.
Sensing in normal mode is defined as normal sensing.
【Intermittent mode】
Detection is thinned out. If the touch detection beyond a definite period of time is not recognized, it will shift to
intermittent operation. In this state, since the frequency of sensing is low, current consumption can be reduced.
Sensing in intermittent operation is defined as check sensing.
【　Normal operation　】
①An effective sensor is sensing by the SENS setting.
Operation
MPU
Analog
SIN0
D
Normal
Standby
Operation
B
Standby
calculation Standby
Standby Standby
Normal
B
Standby
Standby
Operation
calculation Standby
Standby Standby
Normal
B
Standby
Standby
Operation
calculation Standby
Standby Standby
Normal
Standby
Operation
calculation
Standby
SIN1
SIN2
SIN3
【　Intermittent operation　】
①All sensors are checked sensing by each CHK setting of the register.
②The sensor of ON judgment is done normal sensing by the check sensing result, and it uses it for the touch judgment that outputs only the result.
③It stands by until time equal with all channel sensing when sensors of ON judgment are less than 8 channels in the check sensing result.
④It stands by at time that even the next check timing was set when there is no sensor of ON judgment in the check sensing result.
⑤The frequency of the sensor while check sensing is operated is specified by the register. Minimum is 1 time. (A below figure is shown twice.)
Opetration
Check
MPU
Standby calculation
Analog
Operation Standby
SIN0
OFF
SIN1
OFF
SIN2
OFF
SIN3
OFF
A
Standby
Standby
Standby
Check
Standby calculation
Operation Standby
ON
Normal
B
Standby
Standby
Operation
calculation Standby
Standby Standby
Normal
B
Standby
Check
Normal
C
Standby
B
Standby
Normal
C
Standby
Standby
Operation
calculation Standby
Standby calculation Standby calculation
Standby
Standby Standby Operation Standby Operation Standby Standby
Standby Standby calculation
Standby
Standby Operation Standby
Standby
OFF
ON
ON
ON
OFF
ON
OFF
A: Check waiting time. It is possible to set it at CHK_WAIT_TIME. (About 4 to 1024ms)
B: Sense waiting time. It is possible to set it at SENS_WAIT_TIME. (About 0 to 1020ms)
C: Sense adjustment time. It changes according to the number of sensors in which not sensing. (About 4ms unit)
D: Sensing time of each sensor
Figure14. Operation sequence of normal operation and intermittent operation
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TSZ22111・15・001
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TSZ02201-0Y1Y0FZ00150-1-2
2013.09.25 Rev.001