TIDM-02013: Why Is Isolation Used for the Low-Side GaN FET in a Half-Bridge with LMG3522R030?

Salmen Ismail

Part Number: TIDM-02013
Other Parts Discussed in Thread: LMG3522R030, , ISO7710

Tool/software:

Hi,

I’m going to make an EV charger using TI’s GaN FET solution LMG3522R030, and I’m using the evaluation board TIDM-02013 as a reference. I have a question: why is the ISO7710 isolator and an isolated push-pull power supply used for the low-side GaN FET in a half-bridge? On the board, PGND is made common between the power side and the control side. I understand the need for isolation on the high side, but I don’t see the reason for it on the low side.

Thanks,

27 days ago

+1 SUNILBHAI PATEL 27 days ago

Intellectual 330 points

In the TIDM-02013 design with the LMG3522R030 GaN FET, the ISO7710 isolator and isolated push-pull power supply are used for the low-side FET to protect the control circuitry (C2000 MCU) from high-frequency noise, dV/dt transients, and ground bounce caused by the FET's fast switching (up to 150 V/ns). Even with a common PGND, this functional isolation ensures signal integrity and system reliability in a noisy 7.4 kW EV charger environment.

0 Salmen Ismail 25 days ago in reply to SUNILBHAI PATEL

Prodigy 10 points

Thank you so much!

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TIDM-02013: Why Is Isolation Used for the Low-Side GaN FET in a Half-Bridge with LMG3522R030?