Hardware AN3301
6/35 Doc ID 18161 Rev 1
1.2 Power supply
The implementation and layout of the power connection’s section is fundamental for the
correct operation of the STMPE812A touchscreen controller.
The STMPE812A device is equipped with a 12-bit ADC that is used during the touchscreen
controller and auxiliary voltage measurement operations.
The analog blocks require a clean and stable supply voltage in order to operate in optimum
performance. In the STMPE812, the analog blocks and the digital core are supplied by V
CC
.
The operating V
CC
voltage range is 1.65 V to 3.6 V. Power consumption will be increased
with the increase in V
CC
. The lowest power consumption is at V
CC
= 1.8 V.
It is a good practice to connect a 0.1
µF filtering capacitor as close as possible to the V
CC
pin.
1.2.1 Power sequence (fail safe)
All GPIOs and sense pins of STMPE812A are NOT fail safe. This means that it is necessary
to make sure that the V
CC
supply to STMPE812A is first turned before driving the GPIO
inputs.
All other pins (SCL and SDA) are with fail safe structure. It is possible to turn on the pull-up
supply before V
CC
.
