The TPS6521855
provides three current limited load switches with individual inputs, outputs, and
enable control. Each switch provides the following control and diagnostic features:
- The ON or OFF state of the
switch is controlled by the corresponding LSx_EN bit in the ENABLE
register.
- LS1 can be controlled by the sequencer or through
I2C communication.
- LS2 and LS3 can only be controlled through
I2C communication. The sequencer has no control over LS2 and
LS3.
- Each switch has an active
discharge function, disabled by default, and enabled through the LSxDCHRG
bit. When enabled, the switch output is discharged to ground whenever the
switch is disabled.
- When the PFI input drops
below the power-fail threshold (the power-fail comparator trips), the load
switches are automatically disabled to shed system load. This function must
be individually enabled for each switch through the corresponding LSxnPFO
bit. The switches do not turn back on automatically as the system voltage
recovers, and must be manually re-enabled.
- An interrupt (LSx_I) issues
whenever a load switch actively limits the output current, such as when the
output load exceeds the current limit value. The switch remains ON and
provides current to the load according to the current-limit setting.
- All three load switches have
local overtemperature sensors which disable the corresponding switch if the
power dissipation and junction temperature exceeds the safe operating value.
The switch automatically recovers once the temperature drops below the OTS
threshold value minus hysteresis. The LSx_F (fault) interrupt bit is set
while the switch is held OFF by the OTS function.