P

D(max) +

T

J

max * TA

R

q

JA

where:

PWP with no airflow.

P

D +

V

I *

V

O

I

O

TPS767D301-EP

SGLS327A – FEBRUARY 2006 – REVISED APRIL 2010

www.ti.com

Regulator Protection

The TPS767D301-EP PMOS-pass transistor has a built-in back-gate diode that safely conducts reverse currents

when the input voltage drops below the output voltage (e.g., during power down). Current is conducted from the

output to the input and is not internally limited. When extended reverse voltage is anticipated, external limiting

may be appropriate.

The TPS767D301-EP also features internal current limiting and thermal protection. During normal operation, the

TPS767D301-EP limits output current to approximately 1.7 A. When current limiting engages, the output voltage

scales back linearly until the overcurrent condition ends. While current limiting is designed to prevent gross

device failure, care should be taken not to exceed the power dissipation ratings of the package. If the

temperature of the device exceeds 150°C (typ), thermal-protection circuitry shuts it down. Once the device has

cooled below 130°C (typ), regulator operation resumes.

Power Dissipation and Junction Temperature

Specified regulator operation is assured to a junction temperature of 125°C; the maximum junction temperature

should be restricted to 125°C under normal operating conditions. This restriction limits the power dissipation the

regulator can handle in any given application. To ensure the junction temperature is within acceptable limits,

The maximum power dissipation limit is determined using the following equation:

(3)

The regulator dissipation is calculated using:

(4)

Power dissipation resulting from quiescent current is negligible. Excessive power dissipation triggers the thermal

protection circuit.

14

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