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LM5022: Monitor and control for LED driver application

Satoshi
Guru 19645 points
Part Number: LM5022

I designing LM5022 with LED driver application, based on application note: snva282b and snva229a.

I want to attach additional specification below, is there any reference design or information?

①Open LED detection

　⇒Zener diode: D2 is only protection function, I want detect and output signal. 

②Monitoring LED current

　⇒Sensing Vcs and analog output, is there recommended current shunt monitor?

③Constant current need to adjust linearity, controlling from external analog signal (DAC output from FPGA).

　I think that analog signal connect between RFB2 and Q2, is it correct?

Best regards,

Satoshi

  • 0
    TI__Guru* 78300 points

    Hi Satoshi,

    Thank you for designing with the LM5022.  Sorry I don't know any existing reference designs for these functions.  

    If you want to detect LED disconnect: RFB1 voltage would reduce a lot, so you may able to catch it by monitor RFB1 with a comparator.

    The voltage across RFB1 represents the LED current.

    The circuit achieve constant current. If you want to adjust, you should feed your DAC voltage to RFB1 through a scaling resistor.  When you want high current, you need to reduce the DAC voltage.

    Hope these help.

    Thanks,

    Youhao Xi, Applications Engineering