MP2317 – 26V, 1A, SYNCHRONOUS, STEP-DOWN CONVERTER

MP2317 Rev. 1.0

www.MonolithicPower.com

13

3/24/2016

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For ceramic capacitors, the impedance at the

switching frequency is dominated by the

capacitance, which mainly causes the output

voltage ripple. For simplification, the output

voltage ripple can be estimated with Equation

(8):

OUT

OUT

OUT

2

IN

S1

VV

∆V1

V

8f

L

C2



 



 



(8)

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 with

Equation (9):

OUT

OUT

OUT

ESR

IN

S1

VV

∆V1

R

fL

V



 









9)

The characteristics of the output capacitor also

affect the stability of the regulation system. The

MP2317 can be optimized for a wide range of

capacitance and ESR values.

External Bootstrap Diode

An optional, external diode may enhance the

efficiency of the regulator. The conditions of the

external diode are applied when the output

voltage is 5V.

In this case, it is recommended to connect an

Figure 4).

Figure 4: Optional External Bootstrap Diode

Added to Enhance Efficiency

External VCC Diode

of the regulator (see Figure 5).

C4

0.1µF

1N4148

Figure 5: Optional External Diode Added to

Enhance Efficiency