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LM5122: LM5122 over load protection

Red Yen
Expert 4360 points
Part Number: LM5122

Hi support team 

In the datasheet that can saw OLP occurred during CSP-CSN>75mv

If internal 12V short to ground induce reverse current such that CSN>CSP(no matter input UVP)
(1) what the behavior during CSN>CSP

(2) If IC was occurred OLP what is the threshold ?

 

  • 0
    TI__Guru* 78270 points

    Hi Red,

    Thank  you for posting, and we will take a look into this and answer your question tomorrow.

    Best Regards,

    Youhao Xi, Applications Engineering

  • 0 in reply to Youhao Xi
    TI__Guru* 78270 points

    Hi Red,

    I searched the datasheet and I could not identify the "internal 12V" that you referred to.  What to you really mean?  Anyway, answers to your questions:

    (1) if the IC is set to forced PWM, the CSN-CSP>0 will not affect the operation.   However, if the IC is set to diode emulation, then CSN-CSP>0 will turn-off the sync FET, namely HO-SW will stay low.

    (2)  The OLP is basically an inductor peak current limit. If the circuit hit the peak current limit of CSP-CSN=75mV, the duty cycle will be truncated.  the power level limit will vary depending on the Vin voltage.

    Thanks,

    Youhao