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LM5060: In series with LM74610-Q1

nickagian
Prodigy 40 points
Part Number: LM5060
Other Parts Discussed in Thread: , LM74610-Q1, LM74700-Q1

Hi team,

in my application I would like to do what more or less is show here below:

I want to use LM74610 in order to protect against reverse voltage polarity and reverse current.

I also want to use LM5060 in order to monitor the line against over-voltage (and over-current).

My question is whether the order I put the two ICs and their respective NMOS is important or not.

I am thinking: When there is a reverse voltage polarity event, current will first flow through the LM5060 and Q5 before the LM74610 can detect it. Is that a good scenario for the LM5060 or there is a risk of damage on its pins? Would it be better if I put them the other way round?

Nikos

  • 0
    TI__Genius 16305 points

    Hi

    I am looking into this issue, let me get back today.

    Regards,

    Kari.

  • 0 in reply to Karikalan Selvaraj
    TI__Genius 16305 points

    Hi

    LM5060-Q1 is preferred to be placed after LM74610-Q1 (or we recommend LM74700-Q1 for reverse polarity protection instead of LM74610-Q1 which has pulsed ON/OFF behavior at its output, please refer to the datasheet for functional description). 

    When a reverse input is applied at the input, reverse current starts to flow from Q5 and any hold up capacitor after Q5. LM74700-Q1 quickly detects it reverse current through Q1 and turns off before the OUT (after Q5) is discharged and prevents it from swinging negative.

    Having LM5060-Q1 after LM74700-Q1 or LM74610-Q1 protects LM5060-Q1 pins from reverse voltage. This is because cathode of LM74700-Q1 is protected from reverse input voltage.

    In some cases, for example higher over voltage conditions, it is beneficial to place LM5060-Q1 before LM74700-Q1 where LM74700-Q1 and downstream circuits need to be protected from high over voltage. In such case, LM5060-Q1 needs additional circuits to protect itself and downstream from reverse input voltages.

    Regards,

    Kari.

  • 0 in reply to Karikalan Selvaraj
    Prodigy 40 points

    Hi Kari,

    thank you for your reply, much appreciated.

    Just to make sure I understood, the order I have placed the components is also your preferred, isn't it? The LM5060-Q1 after the LM74610-Q1.

    Also I didn't quite get why you recommend LM74700-Q1 instead of LM74610-Q1. What is the advantage it offers in this case? Is it because of what you said, that "cathode of LM74700-Q1 is protected from reverse input voltage"? That isn't true for LM74610-Q1?

    Regards,
    Nikos

  • 0 in reply to nickagian
    TI__Genius 16305 points

    Hi Nikolaos,

    Yes LM5060-Q1 is preferred as it is protected by LM74700 from reverse polarity inputs or transients.

    Output of LM74610 has a pulsed behavior (please refer to datasheet Figure 9 on page 9) and this may not be acceptable for all systems or you may have to filter out using a LC filter.

    Otherwise LM74610 offers similar protection features as LM74700.

    However LM74700 is superior interms of its gate drive strength to support bigger MOSFETs.

    Regards,

    Kari.