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LM5148: Circuit for 65V output

Brian Li
Genius 9405 points
Part Number: LM5148
Other Parts Discussed in Thread: THP210, LM5116, LM5146, LM5145, LM5122

Hi team,

Could you please help check if our LM5148 can use for 65V output?

Are there any other components can be added to the circuit to get a 65V Vout?

We can see from our DS that the max Vout is 55V.

Thanks,

Brian

  • +1
    TI__Mastermind 22299 points

    Hi Brian,

    The current sense pins, ISNS+ and VOUT, have 55V ABS max.

    It may be possible to step down these voltages, but the ISNS+ to VOUT current sense signal is noise sensitive and small signal (<60mV), so I would be hesitant to add external circuits to this.

    -Orlando

  • 0 in reply to Orlando Murray
    TI__Genius 9405 points

    Hi Orlando,

    Could you please help advise an external circuit?

    Thanks,

    Brian

  • +1 in reply to Brian Li
    TI__Mastermind 22299 points

    Hi Brian,

    I spoke with design, you cannot use a resistor divider directly to current sense pins.

    There is some input current on the VOUT pin, so it will not work with series resistors.

    Maybe you can use a fully differential amplifier like THP210.

    You will have to resistor divide down the current sense signal to less than 36V for the differential amplifier, and then supply a low-noise common mode voltage to the amplifier.

    This seems like a challenge and risk, consider using LM5116 as a better fit.

    Hope this helps,

    -Orlando

  • 0 in reply to Orlando Murray
    TI__Genius 9405 points

    Hi Orlando,

    Thanks a lot.

    And customer think this tHO(off) is too big.

    Could you please kindly help advice one with this spec is smaller than 200ns?

    Thanks,

    Brian

  • +1 in reply to Brian Li
    TI__Mastermind 22299 points

    Hi Brian,

    LM5116 looks like the only buck device for 65V VOUT. 

    If they're able to use 60V VOUT then LM5146 and LM5145 are also buck options.

    Usually for 65V output voltage, boost converters at lower VIN are the more common devices.

    Something like LM5122 which can step up 48V VIN to 65V VOUT is more common for higher output voltages.

    Hope this helps,

    -Orlando