MP2130 – HIGH EFFICIENCY, 3.5A, 6V, 1.2MHz SYNCHRONOUS STEP-DOWN CONVERTER

MP2130 Rev. 1.23

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11

11/22/2013

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capacitance to provide sufficient charge to

prevent excessive voltage ripple at input. The

input voltage ripple caused by capacitance can

be estimated by:

LOAD

OUT

OUT

IN

IN

SIN

IV

V

V1

fC1

V

V

⎛⎞

Δ=

×

× −

⎜⎟

×

⎝⎠

Selecting the Output Capacitor

The output capacitor (C2) is required to maintain

the DC output voltage.

Low ESR ceramic capacitors can be used with

MP2130 to keep the output ripple low. Generally,

10μF output ceramic capacitor is enough for

most of the cases. In higher output voltage

condition, 22μF might be needed for a stable

system.

Using ceramic capacitors, the impedance at the

switching

frequency

is

dominated

by

the

capacitance. The output voltage ripple is mainly

caused by the capacitance. For simplification, the

output voltage ripple can be estimated by:

OUT

OUT

OUT

2

IN

S1

VV

ΔV1

V

8f

L

C2

⎛⎞

=× −

⎜⎟

×× ×

⎝⎠

In the case of tantalum or electrolytic capacitors,

the ESR dominates the impedance at the

switching frequency. For simplification, the output

ripple can be approximated to:

OUT

OUT

OUT

ESR

IN

S1

VV

ΔV1

R

fL

V

⎛⎞

=× −

×

⎜⎟

×

⎝⎠

The characteristics of the output capacitor also

affect the stability of the regulation system.

Layout Recommendation of MP2130

Proper layout of the switching power supplies is

very important, and sometimes critical to make it

work properly. Especially, for the high switching

converter, if the layout is not carefully done, the

regulator could show poor line or load regulation,

stability issues.

For MP2130, the high speed step-down regulator,

the input capacitor should be placed as close as

possible to the IC pins. As shown in Figure 6, the

0805 size ceramic capacitor is used, please

make sure the two ends of the ceramic capacitor

be directly connected to PIN1 (the Power Input

Pin) and PIN 3 (the Power GND Pin).

Figure 5—Two Ends off Input Decoupling

Capacitor Close to Pin 1 and Pin 3