ZXLD1370

ZXLD1370

Document number: DS32165 Rev. 4 - 2

18 of 36

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March 2011

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ZXLD1370 Buck-Boost Mode 350mA Minimum Recommended Inductor

Target Switching Frequency > 500kHz

0

10

2030

4050

60

1

3

5

7

9

11

13

15

Supply Voltage (V)

L=22µH

L=33µH

L=47µH

Figure 24. 350mA Buck-Boost mode inductor selection for target frequency > 500kHz

For example, in a Buck-bust configuration (VIN =10-18V and 4 LEDs), with a load current of 350mA; if the target frequency

is around 400kHz, the Ideal inductor size is L= 33uH. The same size of inductor can be used if the target frequency is higher

than 500kHz driving 6LEDs with a current of 350mA from a VIN =12-24V.

In the case of the Boost topology, the following graphs guide the designer to select the inductor for a target frequency of

400kHz (figure 25) or higher than 500kHz (figure 26).

 

ZXLD1370 Boost Mode 350mA Minimum Recommended Inductor

Target Switching Frequency - 400kHz

0

10

2030

40

5060

1

3

5

7

9

11

13

15

Supply Voltage (V)

L=22µH

L=33µH

L=47µH

Figure 25. 350mA Boost mode inductor selection for target frequency 400kHz