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LM74700-Q1: Buck output used to charge battery. Battery reverse polarity protection and reverse current protection required.

AJIT JAIN
Prodigy 185 points
Part Number: LM74700-Q1
Other Parts Discussed in Thread: LM5146,

Hi TI team,

First of all thank you for providing this forum as a platform for clarifying the problems.

We have designed a 300 watt 48V (input) to 14V (output) synchronous buck converter using LM5146 controller to charge an auxiliary battery of 12V. We have used LM74700-Q1 at the output of buck to prevent reverse current. But, we also want to disconnect 12V battery if it is connected in reverse polarity to avoid failure because of high current through low side MOS freewheeling diode.

Can anyone suggest any TI' IC , which can take care of both reverse current and reverse polarity protection?

  • 0
    TI__Guru 57737 points

    Hi Ajit,

    Welcome to e2e!

    LM74700-Q1 can protect from input reverse polarity and has reverse current blocking functionality.

    For output reverse polarity protection, you will need to use an additional PFET based circuitry at the output of LM74700-Q1 as shown below. The PFET will be ON when the GND is lower potential than Vout and the PFET will be OFF when GND is at higher potential than Vout.