AP63200/AP63201/AP63203/AP63205

Table 1 shows a list of recommended component selections for common output voltages for AP6300 and AP63201 referencing Figure 20.

AP63200/AP63201

Output Voltage (V)

R1 (k

Ω)

R2 (k

Ω)

L (µH)

C1 (µF)

C2 (µF)

C3 (nF)

C4 (pF)

1.2

30.9

62

2.2

10

2 x 22

100

100

1.5

54.2

62

2.2

10

2 x 22

100

100

1.8

77.5

62

3.3

10

2 x 22

100

100

2.5

131

62

3.3

10

2 x 22

100

100

3.3

182

62

6.8

10

2 x 22

100

100

5

157

30

10

10

2 x 22

100

100

12

249

18

10

10

2 x 22

100

56

Table 1. Recommended Component Selections for AP63200/AP63201

Tables 2 and 3 show recommended component selections for AP63203 and AP63205 referencing Figure 21.

AP63203

Output Voltage (V)

L (µH)

C1 (µF)

C2 (µF)

C3 (nF)

3.3

3.9

10

2 x 22

100

Table 2. Recommended Component Selections for AP63203

AP63205

Output Voltage (V)

L (µH)

C1 (µF)

C2 (µF)

C3 (nF)

5

4.7

10

2 x 22

100

Table 3. Recommended Component Selections for AP63205

10

Inductor

Calculating the inductor value is a critical factor in designing a buck converter. For most designs, the following equation can be used to calculate

the inductor value:

Eq. 7

Where

to be 30% to 50% of the maximum load current of 2A.

The inductor peak current is calculated by:

Eq. 8

Peak current determines the required saturation current rating, which influences the size of the inductor. Saturating the inductor decreases the

converter efficiency while increasing the temperatures of the inductor and the internal power MOSFETs. Therefore, choosing an inductor with the

appropriate saturation current rating is important. For most applications, it is recommended to select an inductor of approximately 2.2µH to 10µH

with a DC current rating of at least 35% higher than the maximum load current. For highest efficiency, the inductor’s DC resistance should be less

than 100mΩ. Use a larger inductance for improved efficiency under light load conditions.

11

Input Capacitor

The input capacitor reduces the surge current drawn from the input supply as well as the switching noise from the device. The input capacitor has

to sustain the ripple current produced during the on time of Q1. It must have a low ESR to minimize the losses.

The RMS current rating of the input capacitor is a critical parameter and must be higher than the RMS input current. As a rule of thumb, select an

input capacitor which has an RMS rating greater than half of the maximum load current.

Due to large dI/dt through the input capacitor, electrolytic, or ceramics with low ESR should be used. If a tantalum capacitor is used it must be

surge protected or else capacitor failure could occur. Using a ceramic capacitor greater than 10µF is sufficient for most applications.

AP63200/AP63201/AP63203/AP63205

Document number: DS41326 Rev. 2 - 2

13 of 18

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