AP64100Q

Document number: DS43575 Rev. 1 - 2

20 of 26

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July 2021

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AP64100Q

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 = 2.5V



IOUT = 1A



fSW = 500kHz



fC = 20kHz



R1 = 21.5

kΩ



R2 = 10

kΩ



L = 10µH



C2 =

22µF (Effectively, COUT ≈ 15µF)



RC ≈ 5mΩ

AP64100

VIN

EN

SW

BST

FB

GND

INPUT

R1

21.5kΩ

C4

R2

10kΩ

L

10μH

C3

100nF

C2

22µF

C1

2 x 10µF

OUTPUT

VOUT

2.5V

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.

AP64100Q