V

O

V

I

OUT

RESET

10kW

GND

EN

IN

TPS726xx

1 mF

C

O

TPS726126

TPS72615, TPS72616

TPS72618, TPS72625

SLVS403H – MAY 2002 – REVISED JUNE 2010

www.ti.com

APPLICATION INFORMATION

The TPS726xx family of low-dropout (LDO) regulators have numerous features that make it apply to a wide

range of applications. The family operates with very low input voltage (

≥1.8 V) and low dropout voltage (typically

200 mV at full load), making it an efficient stand-alone power supply or post regulator for battery or switch mode

power supplies. Both the active low RESET and 1-A output current, make the TPS726xx family ideal for

with 10-µF output capacitor), making it ideal for use in telecom equipment.

External Capacitor Requirements

A 1-µF or larger ceramic input bypass capacitor, connected between IN and GND and located close to the

TPS726xx, is required for stability. To improve transient response, noise rejection, and ripple rejection, an

additional 10-µF or larger, low ESR capacitor is recommended. A higher-value, low ESR 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, especially if the minimum input voltage of 1.8 V is used.

Although an output capacitor is not required for stability, transient response and output noise are improved with a

10-µF output capacitor.

Figure 18. TPS726xx Fixed Output Typical Application Diagram

Regulator Protection

The TPS726xx 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 TPS726xx also features internal current limiting and thermal protection. During normal operation, the

TPS726xx limits output current to approximately 1.6 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 165°C, thermal-protection circuitry shuts it down. Once the device has cooled down to below

145°C, regulator operation resumes.

THERMAL INFORMATION

The amount of heat that an LDO linear regulator generates is directly proportional to the amount of power it

above which normal operation is not assured. A system designer must design the operating environment so that

main environmental variables that a designer can use to improve thermal performance are air flow and external

heatsinks. The purpose of this information is to aid the designer in determining the proper operating environment

for a linear regulator that is operating at a specific power level.

8

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