LM3431-Q1: the diode selection

Brian lin

Part Number: LM3431-Q1
Other Parts Discussed in Thread: LM3431

Hi Sr

We are using the LM3431 in automotive electronic rearview mirrors. Following the reference circuit provided by TI, we noticed two components (as shown in the diagram below).

We need to replace them with automotive-grade components. D2~D5 (CMPD3003C) and D6~D9 CMPD1001A (CMPD1001A)

Could you kindly provide the parameters we should pay attention to?

such as Reverse Voltage (VR) and Forward Current (If)?...

Thanks

10 months ago

0 Hailee Xu 10 months ago

TI__Expert 8210 points

Hi Brian,

Please give us some time and will get back to you later.

BR,

Hailee.

0 Xiaoguang 10 months ago

TI__Genius 16210 points

Both the CFB and SC diodes must be rated to at least 100 µA, and the CFB diode should have a reverse voltage rating higher than VOUT. With these requirements in mind, it is best to use the smallest possible case size in order to minimize diode capacitance which can slow the LED current rise and fall times.

0 Brian lin 10 months ago in reply to Xiaoguang

Prodigy 50 points

Hi Sr

Okay, I understand. In your application note, it is mentioned that Vf = 1V (when If = 200mA). Do I need to use the same value, or can I use a smaller Vf (e.g., Vf = 0.6V with If = 200mA) Schottky Barrier Diodes ?

Thanks.

0 Xiaoguang 10 months ago in reply to Brian lin

TI__Genius 16210 points

Yes, you can.

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LM3431-Q1: the diode selection