STMPE1600 Polarity inversion register
Doc ID 16938 Rev 3 19/27
9.3 Fail safe conditions
The STMPE1600 IOs (SDA, SCL, INT, A2, A1, A0) are fail-safe IOs that support 4 mA
current drive.
Note that “present” state implies that the supply is present. The “absent” state implies that
the power is lost (grounded) condition. In the fail-safe condition, the leakage current flowing
into the STMPE1600 device is prevented.
Fail Safe condition
When chip supply is 0 V and when V
IO
(SDA, SCL, INT, A2, A1, A0) is 3.6 V, this is classified
as a fail-safe condition. In this case, the chip is protected and the current per I/O is limited to
a very small value.
Overvoltage condition
The second condition is the overvoltage condition which occurs when V
CC
= 1.65 V and
V
IO
= 3.6 V. In this condition, the current drawn by the device per IO can be 10 µA (typical)
and 25
µA (worst case). This device should not be operated under this condition.
So it is recommended to operate the IO at the same voltage as the supply voltage (either
1.8 V or 3.3 V). Also the fail safe IOs are special IOs which can have a voltage present while
the supply voltage V
CC
is 0 V. Current will be limited from the fail safe IOs when supply
voltage V
CC
is 0 V.
Table 10. Fail safe conditions
V
CC
(core and IO supply) Condition
Present Normal operating condition
Absent Complete power-down condition
