RY8310

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©RYCHIP Semiconductor Inc.

30V 1.2A 1.4MHz Synchronous Step-Down Regulator

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Applications Information

Setting the Output Voltage

RY8310 require an input capacitor, an output capacitor and an inductor. These components are critical to the

performance of the device. RY8310 are internally compensated and do not require external components to achieve

stable operation. The output voltage can be programmed by resistor divider.

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VOUT(V)

R1(KΩ)

R2(KΩ)

L1(μH)

C1(nF)

CIN(μF)

COUT(μF)

CFF (pF) Opt.

1.0

2.50

10

2.2

100

22

22×2

CFF Chapter

1.05

3.13

10

2.2

100

22

22×2

CFF Chapter

1.2

5.00

10

2.2

100

22

22×2

CFF Chapter

1.5

8.75

10

2.2

100

22

22×2

CFF Chapter

1.8

12.50

10

3.3

100

22

22×2

CFF Chapter

2.5

21.25

10

3.3

100

22

22×2

CFF Chapter

3.3

31.25

10

4.7

100

22

22×2

CFF Chapter

5.0

52.50

10

4.7

100

22

22×2

CFF Chapter

All the external components are the suggested values, the final values are based on the application testing results.

Selecting the Inductor

The recommended inductor values are shown in the Application Diagram. It is important to guarantee the inductor

core does not saturate during any foreseeable operational situation. The inductor should be rated to handle the

maximum inductor peak current: Care should be taken when reviewing the different saturation current ratings that

are specified by different manufacturers. Saturation current ratings are typically specified at 25°C, so ratings at

maximum ambient temperature of the application should be requested from the manufacturer. The inductor value

can be calculated with:

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������������������������������������×∆������������������������×������������������������������������������������

Where ΔIL is the inductor ripple current. Choose inductor ripple current to be approximately 30% to 40% of the

maximum load current. The maximum inductor peak current can be estimated as:

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Under light load conditions below 100mA, larger inductance is recommended for improved efficiency. Larger

inductances lead to smaller ripple currents and voltages, but they also have larger physical dimensions, lower

saturation currents and higher linear impedance. Therefore, the choice of inductance should be compromised

according to the specific application.