I

RMS +

I

O

(max)

V

O

V

I

1 *

V

O

V

I

DVO + VO

1 *

V

O

V

I

L

f

1

8

Co

f )

R

ESR

I

RMS(Co) +

V

O

1–

V

O

V

I

L

f

1

2

3

TPS62050, TPS62051, TPS62052, TPS62054, TPS62056

SLVS432F – SEPTEMBER 2002 – REVISED JUNE 2015

www.ti.com

Table 3. Inductors (continued)

MANUFACTURER

TYPE

INDUCTANCE

DC RESISTANCE

SATURATION CURRENT

CDR74B

10 µH

70 m

Ω

1.65 A

CDR74B

22 µH

130 m

Ω

1.12 A

CDH74

10 µH

49 m

Ω

1.8 A

CDH74

22 µH

110 m

Ω

1.23 A

Sumida

CDR63B

10 µH

140 m

Ω

1 A

CDRH4D28

10 µH

128 m

Ω

1 A

CDRH5D28

10 µH

48 m

Ω

1.3 A

CDRH5D18

10 µH

92 m

Ω

1.2 A

DT3316P-153

15 µH

60 m

Ω

1.8 A

Coilcraft

DT3316P-223

22 µH

84 m

Ω

1.5 A

WE-PD 744 778 10

10 µH

72 m

Ω

1.68 A

WE-PD 744 777 10

10 µH

49 m

Ω

1.84 A

Wuerth

WE-PD 744 778 122

22 µH

190 m

Ω

1.07A

WE-PD 744 777 122

22 µH

110 m

Ω

1.23 A

10.2.1.2.2

Output Capacitor Selection

The output capacitor must have a minimum value of 22 µF. For best performance, a low ESR ceramic output

capacitor is needed.

For completeness, use Equation 4 to calculate the RMS ripple current.

(4)

The overall output ripple voltage is the sum of the voltage spike caused by the output capacitor ESR plus the

voltage ripple caused by charge and discharging the output capacitor, as shown in Equation 5.

(5)

10.2.1.2.3

Input Capacitor Selection

Because the buck converter has a pulsating input current, 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. The input

capacitor must have a minimum value of 10 µF and can be increased without any limit for better input voltage

filtering. The input capacitor must be rated for the maximum input ripple current calculated as:

(6)

good performance because of their low ESR value and they are less sensitive to voltage transients compared to

tantalum capacitors. Place the input capacitor as close as possible to the input pin of the IC for best

performance.

14

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