Datasheet

Datasheet

22/36

BD81A24MUV-M/EFV-M

TSZ02201-0T3T0C600070-1-2

© 2016 ROHM Co., Ltd. All rights reserved.

2016.10.19 Rev.003

www.rohm.com

TSZ22111・15・001

3.

Selection of the inductor

In order to achieve stable operation of the current mode DC/DC converter, we recommend selecting the L value in the range

indicated below.

0.05[ ⁄ ]<

[ ] ×

[ ]

[

]

< 0.63 ×

[

]

Since there is almost ±30% variation in the value of coil L, keep enough margin and set.

The smaller

[ ]×

[ ]

[

]

allows stability improvement but slows down the response time.

If the condition of VCC is under 5V, please satisfy below equation when selecting the coil.

[

] <

12 ×

[ ] ×

[ ] ×

[ ] ×

[ ] ×

[

]

The coil outside of above equations may cause Low LED brightness.

4.

Selection of Coil L, Diode D1, D2, MOSFET M1, RCS and COUT

Current Rating

Voltage Rating

Heat Loss

Coil L

―

―

Diode D1

> IOCP

> VCC_Max

―

Diode D2

> IOCP

> Vovp_Max

―

MOSFET M1

> IOCP

> VCC_Max

―

―

―

―

>Vovp_Max

―

Please consider external parts deviation and make the setting with enough margin.

In order to achieve fast switching, choose the MOSFET’s with the smaller gate-capacitance.

5.

Selection of Output Capacitor

Select the output capacitor COUT based on the requirement of the ripple voltage Voutpp.

[ ] =

20 ×

[ ]

[

] ×

[ ] ×

+∆ [ ] ×

[ ]

Actually, VOUT ripple voltage is sensitive to PCB layout and external components characteristics. Therefore, when designing

for mass-production, stability should be thoroughly investigated and confirmed in the actual physical design. Available Cout

max value is 500µF.

6.

Selection of Input Capacitor

We recommend an input capacitor greater than 10μF with the small ESR ceramic capacitor. The input capacitor outside of

our recommendation may cause large ripple voltage at the input and hence lead to malfunction.

7.

Selection of BOOT – SW capacitor

When using the Buck Boost application or Buck application, please input BOOT - SW capacitor 0.1µF.