BP5220A Ver la hoja de datos (PDF) - ROHM Semiconductor

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BP5220A

Step-down DC/DC Converters(Non-isolated)

ROHM Semiconductor 

BP5220A/BP5221A/BP5222A

Data Sheet

Application Example 3 : Output voltage adjustment

(1) When reducing the output voltage

(2) When increasing the output voltage

BP5220A / BP5221A / BP5222A

9

7654321

Vi

+ Be sure to use

fuse for safety.

VO

+

VR

BP5220A / BP5221A / BP5222A

9

7654321

Vi

+ Be sure to use

VR

100 F fuse for safety.

VO

+

470 F

Fig.7

Fig.8

VR value setting equations (The output voltage after adjustment is denoted by Vo.)

(1) When reducing the output voltage

BP5220A / BP5221A

BP5222A

(2) When increasing the output voltage

BP5220A / BP5221A

BP5222A

To maximize performance we recommended the output voltage be

adjusted within ±20% of the output voltage rating. When the output voltage is increased by 20%, for

instance, the minimum input voltage is also increased by 20%.

(Example : When the output voltage is changed from 5V to 6V in the BP5220A, the minimum input voltage

is charged from 8V to 9.6V)

Application Example 4 : Slow start

The slow start circuit mitigates the pulse load on the internal switching transistor when input voltage is applied,

and increases the output voltage gradually by starting the switching operation slowly.

This application is useful for preventing malfunction of an external protection circuit due to rush current,

and can serve as a countermeasure against operation outside the safe operation range.

BP5220A / BP5221A / BP5222A

9

7654321

Vi

24V

+

Be sure to use

100 F fuse for safety.

VO

+

470 F

470k

2SC1740R

+ C1

10 F

Fig.9

C1 is a slow-start capacitor for mitigating excessive rush current that flows into the module when the switch is

turned on.

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© 2010 ROHM Co., Ltd. All rights reserved.

5/7

2010.03 - Rev. B

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