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TLV743P

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SBVS310 – JULY 2017

Product Folder Links: TLV743P

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Copyright © 2017, Texas Instruments Incorporated

8.3 Feature Description

8.3.1 Undervoltage Lockout (UVLO)

The TLV743P device uses an undervoltage lockout (UVLO) circuit that disables the output until the input voltage

unpredictable behavior when the supply voltage is lower than the operational range of the internal circuitry.

During UVLO disable, the output connects to ground with a 120-Ω pulldown resistor.

8.3.2 Shutdown

Turn off the device by forcing the EN pin to drop below 0.35 V. If shutdown capability is not required, connect EN

to IN.

The TLV743P device has an internal pulldown MOSFET that connects a 120-Ω resistor to ground when the

(1)

8.3.3 Internal Foldback Current Limit

The TLV743P device has an internal foldback current limit that protects the regulator during fault conditions. The

current allowed through the device is reduced as the output voltage falls. When the output is shorted, the LDO

supplies a typical current of 150 mA. The output voltage is not regulated when the device is in current limit. In

this condition, the output voltage is the product of the regulated current and the load resistance. When the device

triggered and the device turns off. After the device cools down, the internal thermal shutdown circuit turns the

device back on. If the fault condition continues, the device cycles between current limit and thermal shutdown.

See Thermal Information for more details.

The foldback current limit circuit limits the current allowed through the device to current levels lower than the

foldback current limit values. If the output is loaded by a constant-current load during startup, or if the output

voltage is negative when the device is enabled, then the required load current by the load may exceed the

foldback current limit and the device may not rise to the full output voltage. For constant current loads, disable

the output load until the TLV743P has risen to the nominal output voltage.

The TLV743P PMOS pass element has an intrinsic body diode that conducts current when the voltage at the

OUT pin exceeds the voltage at the IN pin. Do not force the output voltage to exceed the input voltage because

excessively high current may flow through the body diode.

8.3.4 Thermal Shutdown

Thermal shutdown protection disables the output when the junction temperature rises to approximately 160°C.

Disabling the device eliminates power dissipated by the device, which allows the device to cool. When the

junction temperature cools to approximately 140°C, the output circuitry is enabled again. Depending on power

dissipation, thermal resistance, and ambient temperature, the thermal protection circuit may cycle on and off.

This cycling limits regulator dissipation, which protects the device from damage as a result of overheating.

Activating the thermal shutdown feature usually indicates excessive power dissipation as a result of the product

maximum. To estimate the margin of safety in a complete design, increase the ambient temperature until the

thermal protection is triggered; use worst-case loads and signal conditions.

The TLV743P internal protection circuitry protects against overload conditions, but is not intended to be active in

normal operation. Continuously running the TLV743P device into thermal shutdown degrades device reliability.