AP64200

Document number: DS43573 Rev. 1 - 2

20 of 26

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March 2021

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AP64200

Application Information (continued)

16

External Loop Compensation Design (continued)

The following is an example of how to choose component values for external loop compensation. Actual component values used in the application

circuit may vary slightly from the calculated first-order approximation equations.

Let the following conditions be defined:



VIN = 12V



VOUT = 1.8V



IOUT = 2A



fSW = 500kHz



fC = 20kHz



R1 = 12.4

kΩ



R2 = 10

kΩ



L = 4.7µH



C2 = 2

× 22µF (Effectively, COUT ≈ 30µF)



RC ≈ 2mΩ

AP64200

VIN

EN

SW

BST

FB

GND

INPUT

R1

12.4kΩ

C4

R2

10kΩ

L

4.7μH

C3

100nF

C2

2 x 22µF

C1

2 x 10µF

OUTPUT

VOUT

1.8V

RT/CLK

COMP

R5

C5

RT

200kΩ

C6

VIN

12V

Figure 30. Example Circuit for Loop Compensation Calculations

The calculations of the main component values involved in the external loop compensation, R5 and C5, are required. If the optional C4 and C6

capacitors are used, their calculations are also required.