The TPS22981 device is a current-limited power mux providing a connection to a peripheral
device from either a low-voltage supply (3 V to 3.6 V) or a high-voltage supply (4.5 V to 19.8 V).
The desired output is selected by digital control signals.
The high-voltage (VHV) and low-voltage (V3P3) switch current limits are set with external
resistance. Once the current limit is reached, the TPS22981 will control the switch to maintain the
current at this limit.
When the high-voltage supply is not present, the TPS22981 will maintain the connection to
the output from the low-voltage supply. Upon the presence of a high-voltage line and high-voltage
enable signal, the high-voltage switch is turned on in conjunction with the low-voltage switch
until a reverse current is detected through the low-voltage switch, allowing a seamless transition
from low voltage to the high-voltage supply with minimal droop and shoot-through current.
To prevent current backflow during a switch over from a VHV connection to a V3P3
connection, the TPS22981 will break the VHV connection, discharge the output to approximately 3.3 V
and then make the V3P3 connection. The output may transition to 0 V when a load is present, before
returning to 3.3 V.
The TPS22981 is available in a 4 mm × 4 mm × 1 mm VQFN package.