R4

1 M

C1

10 µF

C

4.7 µF

OUT

L

VIN

EN

ILIM

GND

VOUT

FB

PG

R

20 k

ILIM

C

1 nF

FF

V

IN

R2

280 k

L1

1 H

R1

1 M

C

>150 µF

BULK

V

OUT

TPS61251

Power Good

Output

2.3 V to

6.0 V

5.5 V

TPS61251

www.ti.com

SLVSAF7B – SEPTEMBER 2010 – REVISED JULY 2015

10 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

10.1 Application Information

The TPS61251 device provides a power supply solution for products powered by either a three-cell, NiCd or

NiMH battery, or a one-cell Li-Ion or Li-polymer battery. The wide input voltage range is ideal to power portable

applications like mobile phones, solid state drives (SSD) and wireless modems. The converter is designed to

charge large capacitors in the Farad range to support battery back up applications.

10.2 Typical Application

Figure 6 shows a typical application for 5.5 V output voltage with input current limit.

Figure 6. Typical Application Schematic

10.2.1 Design Requirements

Table 2 lists the design requirements.

Table 2. Design Parameters

PARAMETER

SYMBOL

VALUE

UNIT

Input Voltage

3.6

V

Minimum Input Voltage

2.9

V

Output Voltage

5.5

V

Input Current Limit set

500

mA

Feedback Voltage

1.2

V

Switching Frequency

f

3.5

MHz

Estimated Efficiency

η

90%

Inductor Value of Choice

L1

1

µH

Copyright © 2010–2015, Texas Instruments Incorporated

Submit Documentation Feedback

11

Product Folder Links: TPS61251