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Isolated gate driver alternative to LTC7001

Category: Hardware
Product Number: LTC7001

A design uses a AD LTC7001 charge pump for gate drive of a highside load switch utilizing an N-channel FET (ONSEMI FDMS86150ET100).

LTC7001 connections:
*Pin 1 (VCC) is set to 12V.
*A silicon diode connects pin 1 (VCC) to pin 9 (BST).
*Pin 8 (TS) is connected to the Source of the FET.
*A 2.2 uF capacitor is connected between pins 8 (TS) and 9 (BST).

With the LTC7001, there's some undesireable current through the N-FET's load to ground, i.e., current flowing before the FET is turned on.

As an alternative, is it possible that an AD isoPower/iCoupler gate drive device, in place of the LTC7001, could solve this problem?

Thank you.

Thread Notes

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  • Yes, the charge pump sources current from the BST pin and out the TS pin (to the output). This current is very small but will raise the output a few voltage with zero output load. A very light load will reduce to voltage to near zero. If you want zero current, an external supply will need to be used to overdrive BST-VCC. If an alternative part includes an isolated supply for the output driver then it should not have this issue.

  • Kurk,

    Thanks for replying. Apologies for my delay in replying.

    I recently bought an evaluation board, EVAL-ADUM4121EBZ, to experiment with isolated gate drive for the load-switch application.

    It will require an isolated power supply for the ADUM4121's output drive. The board has good application notes. I just need to figure out how to mount the board for the tests.

    Thanks again,

    Jeff

Reply
  • Kurk,

    Thanks for replying. Apologies for my delay in replying.

    I recently bought an evaluation board, EVAL-ADUM4121EBZ, to experiment with isolated gate drive for the load-switch application.

    It will require an isolated power supply for the ADUM4121's output drive. The board has good application notes. I just need to figure out how to mount the board for the tests.

    Thanks again,

    Jeff

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