TPS7A2033PDBVR datasheet(11/28 Pages) TI1

11 / 28 page

VOUT(NOM)

0 V

0 mA

VOUT

VFOLDBACK

ICL

ISC

IRATED

IOUT

Brickwall

Foldback

TPS7A20

www.ti.com

SBVS338A – MARCH 2020 – REVISED MARCH 2020

Product Folder Links: TPS7A20

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Feature Description (continued)

Figure 3 shows a diagram of the foldback current limit.

Figure 3. Foldback Current Limit

7.3.5 Undervoltage Lockout (UVLO)

The device has an independent undervoltage lockout (UVLO) circuit that monitors the input voltage, allowing a

controlled and consistent turn on and off of the output voltage. To prevent the device from turning off if the input

drops during turn on, the UVLO has hysteresis as specified in the Electrical Characteristics table.

7.3.6 Thermal Shutdown

The device contains a thermal shutdown protection circuit to disable the device when the junction temperature

(TJ) of the pass transistor rises to TSD(shutdown) (typical). Thermal shutdown hysteresis assures that the device

resets (turns on) when the temperature falls to TSD(reset) (typical).

The thermal time-constant of the semiconductor die is fairly short, thus the device may cycle on and off when

thermal shutdown is reached until power dissipation is reduced. Power dissipation during startup can be high

from large VIN – VOUT voltage drops across the device or from high inrush currents charging large output

capacitors. Under some conditions, the thermal shutdown protection disables the device before startup

completes.

For reliable operation, limit the junction temperature to the maximum listed in the Recommended Operating

Conditions table. Operation above this maximum temperature causes the device to exceed its operational

specifications. Although the internal protection circuitry of the device is designed to protect against thermal

overall conditions, this circuitry is not intended to replace proper heat sinking. Continuously running the device

into thermal shutdown or above the maximum recommended junction temperature reduces long-term reliability.

7.3.7 Active Discharge

The device has an internal pulldown MOSFET that connects an RPULLDOWN resistor to ground when the device is

disabled to actively discharge the output voltage. The active discharge circuit is activated by the enable pin or by

the undervoltage lockout (UVLO).

TPS7A2033PDBVR Datasheet(PDF) 11 Page - Texas Instruments