OUT

IN

OUT

OUT

V

1

V

1

V

V

ESR

L

f

8

Cout

f

-

æ

ö

D

=

´

´

+

ç

÷

´

´

´

è

ø

OUT

OUT

IN

RMSC

OUT

V

1

V

1

I

V

L

f

2

3

-

æ

ö

=

´

´ ç

÷

´

´

è

ø

TPS62290, TPS62291, TPS62293

www.ti.com

SLVS764F – JUNE 2007 – REVISED JANUARY 2016

At nominal load current, the device operates in PWM mode and the RMS ripple current is calculated as:

(4)

At nominal load current, the device operates in PWM mode and the overall output voltage ripple is the sum of the

voltage spike caused by the output capacitor ESR plus the voltage ripple caused by charging and discharging the

output capacitor:

(5)

At light load currents the converter operates in power save mode and the output voltage ripple is dependent on

the output capacitor and inductor value. Larger output capacitor and inductor values minimize the voltage ripple

in PFM mode and tighten DC output accuracy in PFM mode.

9.2.2.2.3

Input Capacitor Selection

The buck converter has a natural pulsating input current; therefore, a low ESR input capacitor is required for best

input voltage filtering and minimizing the interference with other circuits caused by high input voltage spikes. For

most applications, a 10-

μF ceramic capacitor is recommended. The input capacitor can be increased without any

limit for better input voltage filtering.

Take care when using only small ceramic input capacitors. When a ceramic capacitor is used at the input and the

instability or could even damage the part by exceeding the maximum ratings.

Table 3. List of Capacitor

CAPACITANCE

TYPE

SIZE

SUPPLIER

10

μF

GRM188R60J106M69D

Murata

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