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LM74930-Q1: Battery Surge Protection Circuit With LM74930-Q1

Oguzhan GUVERCIN
Prodigy 31 points
Part Number: LM74930-Q1


Hi,

I am planning to use the LM74930-Q1 as the surge protection IC for a battery protection circuit.
But since I'm trying to protect the battery in this case. I need to supply the circuit from my battery, which will be in the output, to be protected.  Because if I try to supply the circuit from the input (where would the surges and overcurrents come from) circuit would only work when there is a charger connected to the terminals, and would not work when the battery is supposed to supply a load. 

So long story short, would LM74930-Q1 work if I supply it from the output if:

-I use the IC in overvoltage clamp mode, so there is always voltage in the output. (Other than reverse polarity event)

-I pull the MODE pin to GND to allow current in both directions.

Would current protections cause any problems when the battery is discharging current into the load? (There is reverse current in the bus.) If so, can I disable the current protections in some way? I already have overcurrent protections on the battery side. I just need input reverse polarity, and surge clamp functionality from the IC.

  • 0
    TI__Guru 54700 points

    Hi,

    Unfortunately, if powered up from output, it cannot work. Once startup happens from VIN side, you can use the controller for bidirectional path. Otherwise, we cant use it.

    Regards,

    Shiven Dhir

  • 0 in reply to Shiven Dhir
    Prodigy 31 points

    Hi, 
    Thanks for the reply.


    But there will be voltage on the output, so battery on the output will be able to supply current to the IC. So I can't power this IC up from an external source? What is the main reason for starting-up the from VIN? Is it having voltage on the output without anything in the input?

    Best regards,

  • 0 in reply to Oguzhan GUVERCIN
    TI__Guru 54700 points

    Hi Oguzhan,

    Powering up externally on VS may cause issues, We usually want to startup such that VS and power rail are at the same voltage.

    This makes sure charge pump has enough drive to power up things.

    Also, some internal circuits may violate its design rules when VS is powered up but rest of the pins are unpowered.

    Regards,

    Shiven Dhir

  • 0 in reply to Shiven Dhir
    Prodigy 31 points

    Hi Shiven,

    OK now I understand your concerns. 
    Is there any surge controller IC that you can recommend for this kind of topology where It can also be supplied from output without any issues. 

    Best regards,