Datasheet

OVERCURRENT ( OC)
CURRENT SENSE
THERMAL SENSE
UNDERVOLTAGE LOCKOUT
TPS2049
SLVS713A – OCTOBER 2006 – REVISED SEPTEMBER 2007 ......................................................................................................................................... www.ti.com
The OC open-drain output is asserted (active low) when an overcurrent or overtemperature condition is
encountered. The output remains asserted until the overcurrent or overtemperature condition is removed. A
10-ms deglitch circuit prevents the OC signal from oscillation or false triggering. If an overtemperature shutdown
occurs, the OC is asserted instantaneously.
A sense FET monitors the current supplied to the load. The sense FET measures current more efficiently than
conventional resistance methods. When an overload or short circuit is encountered, the current-sense circuitry
sends a control signal to the driver. The driver in turn reduces the gate voltage and drives the power FET into its
saturation region, which switches the output into a constant-current mode and holds the current constant while
varying the voltage on the load.
The TPS2049 implements a thermal sensing to monitor the operating temperature of the power distribution
switch. In an overcurrent or short-circuit condition, the junction temperature rises. When the die temperature rises
to approximately 140 ° C due to overcurrent conditions, the internal thermal sense circuitry turns off the switch,
thus preventing the device from damage. Hysteresis is built into the thermal sense, and after the device has
cooled approximately 10 degrees, the switch turns back on. The switch continues to cycle off and on until the
fault is removed. The open-drain false reporting output ( OC) is asserted (active low) when an overtemperature
shutdown or overcurrent occurs.
A voltage sense circuit monitors the input voltage. When the input voltage is below approximately 2V, a control
signal turns off the power switch.
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