AP64202

Document number: DS43574 Rev. 1 - 2

14 of 21

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March 2021

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AP64202

Application Information (continued)

10

Setting the Output Voltage

The AP64202 has adjustable output voltages, starting from 0.8V, using an external resistive divider. The resistor values of the feedback network

are selected based on a design trade-off between efficiency and output voltage accuracy. There is less current consumption in the feedback

network for high resistor values, which improves efficiency at light loads. However, values too high cause the device to be more susceptible to

noise affecting its output voltage accuracy. R1 can be determined by the following equation:

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������������������������

������. ������������

− ������)

Eq. 6

Table 1 shows a list of recommended component selections for common AP64202 output voltages referencing Figure 1.

Table 1. Recommended Components Selections, fSW = 500kHz

AP64202

Output Voltage

(V)

R1

(k

Ω)

R2

(k

Ω)

L

(µH)

C1

(µF)

C2

(µF)

C3

(nF)

1.2

4.99

10

3.3

2 x 10

2 x 22

100

1.5

8.66

10

4.7

2 x 10

2 x 22

100

1.8

12.40

10

4.7

2 x 10

2 x 22

100

2.5

21.50

10

6.8

2 x 10

2 x 22

100

3.3

31.60

10

6.8

2 x 10

2 x 22

100

5.0

52.30

10

10.0

2 x 10

2 x 22

100

12.0

140.00

10

22.0

2 x 10

2 x 22

100

11

Adjusting Soft-Start Time

The AP64202 features an adjustable soft-start time to prevent inrush current during the start-up sequence. Connect an external soft-start capacitor,

CSS, from the SS pin to ground.

The SS pin sources an internal 4µA current to charge CSS when the EN pin exceeds the device’s turn-on threshold. AP64202 uses the lower

voltage between the SS pin voltage and the internal 0.8V reference voltage as the input reference voltage for the error amplifier to regulate the

output. Soft-start finishes when the SS pin voltage exceeds the 0.8V internal reference. The CSS capacitance required for a given soft-start time is

approximated by:

������������������[������������] ≈ ������. ������ ∙ ������������������[������������]

Eq. 7

Where:



CSS is the capacitance in nF and is at least 10nF



tSS is the soft-start time in ms and is at least 3ms