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LMG1020: LMG1020-EVM-006 evaluation board to drive the laser diode

Zhonghui Xu
Expert 5445 points
Part Number: LMG1020

Hi team,

We are using the Texas Instruments LMG1020-EVM-006 evaluation board to drive the laser diode. The attachment shows the results of experimental result. Yellow line shows the pulse pattern given to the EVM board by FPGA. Blue line is measured at monitoring port after gate driver which shows oscillating result with around 18ns between adjacent peaks. Yellow line is the measured output of the laser diode which also shows multiple peak result. The pattern generated by FPGA is 50kHz and 180ns. Can you comment on the oscillation measured at Gate voltage and laser output? 

Best regards,

  • 0
    TI__Genius 13445 points

    Hello,

    Thanks for your help promoting our drivers.

    I assume you meant CH-2 green waveform is the pulse pattern given to the EVM board by FPGA.

    If so, can you confirm your measurement techniques? Are you using tip & barrel method to capture the different signals? I ask because long GND leads will introduce significant stray inductance in the gate drive path causing ringing.

    I also assume no modifications have been made to the board and was powered as is, please confirm.

    With the appropriate GND, your should expect less ringing profile on both IN and gates as well as ~180ns (+/-) pulse durations at the gate.

    If the ringing persists, we will follow up via email to continue debug.

    Meanwhile, I will mark this thread as "resolved".

    Regards,

    -Mamadou

  • 0 in reply to Mamadou Diallo
    TI__Expert 5445 points

    Hi  Mamadou,

    Thank you very much.

    We found that the oscillation may caused by the low voltage level of FPGA. After giving higher amplitude of the FPGA signal, the output signal is improved. However, there is another question. When we apply the driving voltage to the laser, the driving current keeps increasing gradually from 5mA to around 6/7mA at around 65V in one minute. Can you comment on the current instability?

    Best regards,

  • 0 in reply to Zhonghui Xu
    TI__Genius 13445 points

    Hello Zhonghui,

    I will send you an email where we may follow up for any additional questions.

    Meanwhile I will mark this as resolved.

    Regards,

    -Mamadou