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LMG3410R050: LMG341xR050 for high current pulse generator

Hyung-gu
Prodigy 30 points
Part Number: LMG3410R050
Other Parts Discussed in Thread: LMG1020

Hi

For the LiDAR system, very high current pulse for the LD driving is necessary. 

And the max current is depends on the target distance to detect. 

Now I'm developing long distance LiDAR system, so I need over 50A, and under 20ns pulse current. ( but the frequency is not high)

So I checked this device LMG431xR050, 

I want to know this device is suitable for the current pulse controller?

If yes, do I need to make it isolated from the controller?

In the EVM board user guide(snou165a.pdf), it is fully isolated. 

Please tell me your answer. 

Thank you

  • 0
    TI__Genius 16390 points

    Hello Hyung-gu,

    Thanks for reaching out to us. Our LMG3410R050 device can withstand <100ns pulse current up to 130A, and should be okay for this application.

    For the high side devices, isolation is required since the high side ground needs to be fully isolated. For the low side device, isolation is optional but strongly suggested. Low side isolation can greatly reduce the chances for ground bounce caused from parasitic inductance in the PCB.

    Out of curiosity, may I know the following information?

    1. Why you are considering GaN in this application? What benefits are you trying to get out of it?

    2. What is the topology and what will be the switching frequency?

    Thanks!

    Regards, 

  • 0 in reply to Yichi Zhang.
    Prodigy 30 points

    Thank you for quick answer

    1. Why you are considering GaN in this application? What benefits are you trying to get out of it?

    :  For this spec. "over 50A, under 20ns pulse width "  I think GaN should be the best answer.  It has low Ron( 50mohm). 

      Actually, I'm considering another combination as LMG1020 + EPC2010C. EPC2010C has lower Ron

    2. What is the topology and what will be the switching frequency?

    The switching frequency is not high, it will be under 10kHz

    and the topology is low side driving. 

    For the isolation issue, I think it is difficult to apply to my new design. 

    Because timing accuracy is very important in this design. But the isolation circuit has long time latency or ns scale jitters. 

    If you have some idea for it, please tell me 

    I have one more issue

    You said that the current is up to 130A, but the current trip point(for the OCP operation) is 54A. 

    So if I drive under 20ns pulse width, which number(130 or 54) could be the maximum current ?

    Thank you !!

  • 0 in reply to Hyung-gu
    TI__Genius 16390 points

    Hello Hyung-gu,

    Yes, LMG1020 is a great option. Please refer to the following user guide for the LMG1020 based Lidar EVM. 

    http://www.ti.com/lit/ug/snou150a/snou150a.pdf

    For your question, the overcurrent protection will have a 55ns blanking time. During this time frame, the OCP will not come in, and the maximum current allowed is still 130A.

    Yes, I agree for application requires such short pulses, the delay in the circuit can be an issue.

    Regards,