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LM3429BKBSTEVAL: Challenges While driving higher number of LEDs .

Sreejith P Kumar
Prodigy 10 points
Part Number: LM3429BKBSTEVAL

Tool/software:

Using the evaluation board Driving up to 9 LED works fine . When no of led increased to 20 The LEDs are flickering. Inductance and Capacitance values are increased Further details are mentioned below 

LED Forward Voltage = 2.8V 
Number of LEDs = 20
Expected Output Voltage = 60 V (Approx) 
O/P Current = 1A 

  • 0
    TI__Mastermind 23116 points

    Reply will be delayed due to US Holiday. 

    In the mean time you need to provide use with waveforms of inductor current, switch node, and output voltage.  You literally more than doubled the output power and likely need to adjust current limit and potentially compensation.  You also didn't list the input voltage in the specifications.  That board was never designed for that much output power and will likely need to be changed to support it.  You are also really close to the abs max rating of the part of 65V with little margin.  Did you go through the entire design process to adjust for all the features?  You need to do that.  For example the OVP probably needs to be changed.

    -fhoude

  • 0
    TI__Expert 5680 points

    Hi Sreejith, 
    What modifications have you made to our EVM?

    Best,
    Daniel