6.3.5 Thermal Protection

Thermal protection disables the output when the junction temperature rises to approximately 165°C, allowing

the device to cool. When the junction temperature cools to approximately 140°C, the output circuitry is again

enabled. Depending on power dissipation, thermal resistance, and ambient temperature, the thermal protection

circuit may cycle on and off. This cycling limits regulator dissipation, protecting the device from damage as

a result of overheating. Any tendency to activate the thermal protection circuit indicates excessive power

dissipation or an inadequate heatsink. For reliable operation, junction temperature must be limited to 125°C

maximum. To estimate the margin of safety in a complete design (including heatsink), increase the ambient

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

The TPS792xx internal protection circuitry is designed to protect against overload conditions. This circuitry is

not intended to replace proper heatsinking. Continuously running the TPS792xx into thermal shutdown degrades

device reliability.

6.3.6 Reverse Current

The legacy chip of TPS792xx PMOS-pass transistor has a built-in back diode that conducts reverse current

when the input voltage drops below the output voltage (for example, during power down). Current is conducted

from the output to the input and is not internally limited. If extended reverse voltage operation is anticipated,

external limiting to 5% of the rated output current is recommended.

The new chip of TPS792xx, as with most modern LDOs, excessive reverse current can damage this device.

Reverse current flows through the body diode on the pass element instead of the normal conducting channel.

At high magnitudes, this current flow degrades the long-term reliability of the device as a result of one of the

following conditions:

• Degradation caused by electromigration

• Excessive heat dissipation

• Potential for a latch-up condition

TPS792

SLVS337E – MARCH 2001 – REVISED JANUARY 2025

www.ti.com

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