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APPLICATION INFORMATION

TPS71533

IN

OUT

V

IN

V

OUT

C1

0.1

µF

0.47

µF

GND

External Capacitor Requirements

Power Dissipation and Junction Temperature

P

D(max) +

T

J

max * TA

R

q

JA

(1)

P

D

I

OUT

(2)

Regulator Protection

Programming the TPS71501 Adjustable LDO Regulator

TPS71501

TPS71525, TPS71530

TPS71533, TPS71550

SLVS338I – MAY 2001 – REVISED JANUARY 2005

The TPS715xx family of LDO regulators has been optimized for ultra-low power applications such as the

MSP430 microcontroller. Its ultralow supply current maximizes efficiency at light loads, and its high input voltage

range makes it suitable for supplies such as unconditioned solar panels.

Figure 13. Typical Application Circuit (Fixed Voltage Version)

Although not required, a 0.047-µF or larger input bypass capacitor, connected between IN and GND and located

close to the device, is recommended to improve transient response and noise rejection of the power supply as a

whole. A higher-value input capacitor may be necessary if large, fast-rise-time load transients are anticipated and

the device is located several inches from the power source.

The TPS715xx requires an output capacitor connected between OUT and GND to stabilize the internal control

loop. Any capacitor (including ceramic and tantalum)

≥ 0.47 µF properly stabilizes this loop.

To ensure reliable operation, worst-case junction temperature should not exceed 125

°C. This restriction limits the

power dissipation the regulator can handle in any given application. To ensure the junction temperature is within

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

where:

•

•

•

The regulator dissipation is calculated using:

Power dissipation resulting from quiescent current is negligible.

The TPS715xx PMOS-pass transistor has a built-in back diode that 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 operation is anticipated, external limiting might be

appropriate.

The TPS715xx features internal current limiting. During normal operation, the TPS715xx limits output current to

approximately 500 mA. When current limiting engages, the output voltage scales back linearly until the

overcurrent condition ends. Take care not to exceed the power dissipation ratings of the package.

The output voltage of the TPS71501 adjustable regulator is programmed using an external resistor divider as

shown in Figure 14. The output voltage operating range is 1.2 V to 15 V, and is calculated using:

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