TPS76425, TPS76427, TPS76428, TPS76430, TPS76433

LOW-POWER LOW-NOISE 150-mA LOW-DROPOUT LINEAR REGULATORS

SLVS180A – MARCH 1999 – REVISED JUNE 1999

13

POST OFFICE BOX 655303

APPLICATION INFORMATION

power dissipation and junction temperature

Specified regulator operation is assured to a junction temperature of 125

°C; the maximum junction temperature

allowable without damaging the device is 150

°C. This restriction limits the power dissipation the regulator can

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

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

P

D(max) +

T

J

max

* T

A

RqJA

Where

SOT23.

The regulator dissipation is calculated using:

P

D +

V

I *

V

O

I

O

Power dissipation resulting from quiescent current is negligible.

regulator protection

The TPS764xx pass element has a built-in back diode that safely conducts reverse current 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. If extended reverse voltage is anticipated, external limiting might be

appropriate.

The TPS764xx also features internal current limiting and thermal protection. During normal operation, the

TPS764xx limits output current to approximately 800 mA. 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 165

°C, thermal-protection circuitry shuts it down. Once the device has

cooled down to below 140

°C, regulator operation resumes.