V

O +

V

ref

1

)

R1

R2

R1

+

V

O

V

ref

* 1

R2

V

O

V

I

OUT

FB

R1

R2

GND

EN

IN

TPS72501

1 mF

C

O

V

=1.22V ´

O

1+

R1

R2

TPS72501

TPS72515, TPS72516

TPS72518, TPS72525

www.ti.com

SLVS341E – MAY 2002 – REVISED JUNE 2010

APPLICATION INFORMATION

The TPS725xx family of low-dropout (LDO) regulators has numerous features that make it applicable 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 TPS725xx family ideal for powering

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

TPS725xx, 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.

Programming the TPS72501 Adjustable LDO Regulator

The output voltage of the TPS72501 adjustable regulator is programmed using an external resistor divider as

shown in Figure 18. The output voltage is calculated using:

(1)

Where:

•

Resistors R1 and R2 should be chosen for approximately 10-µA divider current. Lower value resistors offer no

inherent advantage and waste more power. Higher values should be avoided as leakage currents at FB increase

the output voltage error. The recommended design procedure is to choose R2 = 120 k

Ω to set the divider current

at 10 µA and then calculate R1 using:

(2)

Figure 18. TPS72501 Adjustable Typical Application Diagram

Copyright © 2002–2010, Texas Instruments Incorporated

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Product Folder Link(s): TPS72501 TPS72515 TPS72516 TPS72518 TPS72525