³

´

2

L

C

2

´

>

´

OUT

OUT

IN

V

I

0.8

100 mA

V

´

ì

ï

´

í

ï

î

OUT

OUT

IN

L,MAX

V

I

+ 100 mA;

continous current operation

0.8 V

I

=

200 mA;

discontinuous current operation

´

´

´

IN

OUT

IN

OUT

V

(V

- V )

1

L =

f 200 mA

V

TPS61220, TPS61221, TPS61222

SLVS776B – JANUARY 2009 – REVISED NOVEMBER 2014

www.ti.com

Typical Applications (continued)

(1)

Choosing inductor values higher than 4.7

μH can improve efficiency due to reduced switching frequency and

therefore with reduced switching losses. Using inductor values below 2.2

μH is not recommended.

Having selected an inductance value, the peak current for the inductor in steady-state operation can be

calculated. Equation 2 gives the peak-current estimate.

(2)

Equation 2 provides a suitable inductor current rating. However, remember that load transients and error

conditions may cause higher inductor currents.

Equation 3 provides an easy way to estimate whether the device will work in continuous or discontinuous

operation depending on the operating points. As long as the Equation 3 is true, continuous operation is typically

established. If Equation 3 becomes false, discontinous operation is typically established.

(3)

The following inductor series from different suppliers have been used with TPS6122x converters:

Table 2. List Of Inductors

VENDOR

INDUCTOR SERIES

EPL3015

Coilcraft

EPL2010

Murata

LQH3NP

Tajo Yuden

NR3015

Wurth Elektronik

WE-TPC Typ S

11.2.1.2.4

Capacitor Selection

11.2.1.2.4.1

Input Capacitor

An input capacitor value of at least 10

μF is recommended to improve transient behavior of the regulator and

EMI behavior of the total power supply circuit. A ceramic capacitor placed as close as possible to the VIN and

GND pins of the IC is recommended.

11.2.1.2.4.2

Output Capacitor

VOUT and GND pins of the IC. If, for any reason, the application requires the use of large capacitors which

cannot be placed close to the IC, the use of a small ceramic capacitor with a capacitance value of around 2.2

μF

in parallel to the large one is recommended. This small capacitor should be placed as close as possible to the

VOUT and GND pins of the IC.

A minimum capacitance value of 4.7

μF should be used, 10 μF is recommended. If the inductor value exceeds

4.7

μH, the value of the output capacitance value needs to be half the inductance value or higher for stability

reasons, see Equation 4.

(4)

14

Submit Documentation Feedback

Copyright © 2009–2014, Texas Instruments Incorporated

Product Folder Links: TPS61220 TPS61221 TPS61222