STMPE821_09 Datasheet, PDF (10/55 Pages) STMicroelectronics – 8-channel capacitive touch key controller

STMPE821 functional overview
1.5
Power management
The STMPE821 operates in 3 states.
Figure 4. STMPE821 operating states
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(OSTCOMMAND
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(OTKEY
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_INTERRUPTAND
HOSTCOMMAND
(OSTCOMMAND
STMPE821
(OSTCOM MAND
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On RESET, the STMPE821 enters the ACTIVE state immediately.
Upon a fixed period of inactivity, the device enters into the SLEEP state. Any touch activity in
SLEEP state would cause the device to go back to ACTIVE state.
In SLEEP mode:
-Calibration continues if F2A bit is set in CONTROL register
-Calibration stops if F2A bit is NOT set in CONTROL register
If no touch activity is expected, the host may set the device into HIBERNATE state to save
power.
If any key is touched and held, the I²C command to enter sleep or hibernate will be put on
hold, until the key has been released.
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