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LT4363 3-500 uA leakage through SNS in shutdown mode

In shutdown mode the LT4363 is supposed to have 7 uA. However, if external power is supplied on the OUT / SNS pins, the leakage rises to 3-500 uA.

This leakage is rather substantial and is not mentioned in the datasheet as far as i can tell.

It is inconvenient for us because we use the LT4363 as an input protection (over voltage and over charge current) on a battery, so the OUT/SNS pins actually never goes to ground, even though we switch off the enable signal (see attached schematics)

If you have any idea of why this happens, and what we could have done to see this, from the datasheet, it would be appreciated.

Thank you,

Johan Christiansen

  • Hello Johan,  The LT4363 is not designed for a power supply (battery) at the output. The output power goes to the input through the MOSFET body diode. You can either add a series diode at the output (passive or ideal such as LTC4359) or use the LTC4364, which incorporates an ideal diode to block reverse current from the output towards the input.

  • I know that.

    I do have a second 4363 next to it. I need to current limit both input (charge) and output (discharge), with different thresholds.

    The question is regarding our observation. That there os a very large leakage into the out pin, when in standby mode.

    If you say that is by design, it would have been nice if there was a notice in the datasheet about that. We have wasted a lot of money because of this leakage. and need to redesign our product.

  • In shutdown, GATE is pulled down. If OUT is held up (unexpected operation for LT4363), this GATE pulldown current will go through the internal GATE-OUT 14V clamp (datasheet page 9) to OUT.