VOUT(NOM)

0 V

0 mA

VOUT

VFOLDBACK

ICL

ISC

IRATED

IOUT

Brickwall

Foldback

14

TLV752

SBVS383A – DECEMBER 2019 – REVISED MARCH 2020

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Feature Description (continued)

For this device, VFOLDBACK = 0.4 V × VOUT(NOM).

The output voltage is not regulated when the device is in current limit. When a current limit event occurs, the

device begins to heat up because of the increase in power dissipation. When the device is in brickwall current

limit, the pass transistor dissipates power [(VIN – VOUT) × ICL]. When the device output is shorted and the output

is below VFOLDBACK, the pass transistor dissipates power [(VIN – VOUT) × ISC]. If thermal shutdown is triggered, the

device turns off. After the device cools down, the internal thermal shutdown circuit turns the device back on. If

the output current fault condition continues, the device cycles between current limit and thermal shutdown. For

more information on current limits, see the Know Your Limits application report.

Figure 39 shows a diagram of the foldback current limit.

Figure 39. Foldback Current Limit

7.3.4 Thermal Shutdown

Thermal shutdown protection disables the output when the junction temperature rises to approximately 170°C.

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

junction temperature cools to approximately 155°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 LDO from damage as a result of overheating.

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

of the (VIN – VOUT) voltage and the load current. For reliable operation, limit junction temperature to 125°C

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 TLV752 internal protection circuitry protects against overload conditions but is not intended to be activated in

normal operation. Continuously running the TLV752 into thermal shutdown degrades device reliability.