AN246 View Datasheet(PDF) - STMicroelectronics
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AN246 Datasheet PDF : 13 Pages
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AN2466
Pin description of STMPE801
Figure 9. Hotkey detection using external pull-up/pull-down resistors on GPIO
2.6
2.7
Note:
Minimum pulse width
Typically a minimum pulse width of 2 microseconds is required on the GPIO for Hotkey
detection. Any pulse width less than the stated value may not be registered in the ISGPIOR.
Power saving mode of operation
STMPE801 operates entirely on the I2C clock. When there is no activity on the I2C bus, the
current consumption of the device is extremely low. However, when there is activity on the
I2C bus, current consumption increases, even if the I2C traffic is not directed to the assigned
address.
The host system may choose to shut-down the I2C block in the STMPE801, if no access to
the registers is required. This feature allows the current consumption to drop to the
minimum. The host can turn OFF the I2C block by writing '1' into the I2C_SHDN bit in the
SYSCON register. The I2C block shuts down on the next valid clock edge of the I2C clock
signal. In this state, the device cannot be accessed by I2C, as the I2C block has shut down
completely.
The ACK from STMPE801 for a I2C SHDN command is kept low only for around 250 µs after
the SCL goes high. After this duration the device I2C block shuts down and the SDA line is
released. The I2C host should sample the ACK within this interval.
To turn ON the I2C block, the system host must reset the STMPE801. This can be
accomplished by an active low signal on the RESET_N pin.
Table 8. Typical current rating (VCC = VIO = 3 V)
Operating modes
Typical VIO current consumption at Ta = 25 °C
Normal operation mode with all outputs switching
and continuous activity on I2C bus
I2C Shutdown mode
~ 10 µA
<10 nA
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