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I want to use an H-Bridge module as a switch in a 12V DC circuit and would prefer, if possible, for ease and simplicity, to use a full-bridge gate driver such as the IRS2453DS. The H-Bridge comprises 4 IGBTs, rated for 75A, and the intention is for a very slow switching rate of 4 to 8Hz.

From the H-Bridge switch datasheet, the gate capacitance of these IGBTs is about 4.3nF, and the gate charge 166nC. The saturation voltage is 15V and the Vgs threshold is ~4V. (Gate-Source leakage current 120nA).

Because the switching rate is so slow - on/off periods in the millisecond range - my understanding so far is that the typical 0.26A sink and 0.18A source currents of this specific gate driver are sufficient for the gate capacitance involved. The bootstrap capacitor incorporated is 0.1μF, well above the gate capacitance.

My question then is whether, broadly speaking (if such is even possible in electronics), this full-bridge driver is even anywhere close to appropriate for such an application, and if not, why not? Any guidance would be much appreciated.

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  • \$\begingroup\$ The best thing to do would be to simulate it in spice, make sure the gate transitions happen as fast as possible and that there is no crossover (two gates on top and bottom fets at the same time). \$\endgroup\$
    – Voltage Spike
    Jan 25, 2021 at 19:05
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    \$\begingroup\$ “very slow switching rate of 4 to 8Hz.” This may rule out bootstrapping and force you to have a floating power supply for your upper MOSFETs. \$\endgroup\$
    – winny
    Jan 25, 2021 at 19:06
  • \$\begingroup\$ @winny Why does a slow switching rate make bootstrapping difficult? \$\endgroup\$
    – jeremiah
    Jan 25, 2021 at 20:33
  • \$\begingroup\$ @Voltage Spike I'll try SPICE, which I'd never heard of before -- so thanks for the direction. \$\endgroup\$
    – jeremiah
    Jan 25, 2021 at 20:35
  • \$\begingroup\$ Because bootstrapping is basically AC coupling with a diode to block one half of the waveform and AC coupling at 4 Hz = a very large capacitor. I’m not saying you can’t make it work, I’m saying you should be aware and start looking at a floating supply for it. Also, I would not go anywhere near an H bridge without spending weeks learning SPICE. \$\endgroup\$
    – winny
    Jan 25, 2021 at 21:52

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Usage of IGBT's at 12V looks strange - there are very cheap MOSFETs that can drive hundreds of Amps and still have a very low RDSon.

At rates like 4Hz bootstrap, the driver might be insufficient - an external isolated low-power PSU would power the high side transistors for as long as you want. A transformer drive is not a thing there due to the enormous inductance needed at such low frequencies.

For powering high-side switches one can use a simple NE555 charge pump or any other boost converter.

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  • \$\begingroup\$ I needed a prefabricated H-Bridge module and that's all I could find. It still should function at 12V, right. I already have what I think is a suitable high-side gate driver [ucc5390 from TI], but without technical experience wondered whether a full bridge driver might fit the scenario better. \$\endgroup\$
    – jeremiah
    Jan 25, 2021 at 20:54
  • \$\begingroup\$ At only 12 V, you can probably cheat and use a capable driver directly. IXYS IXD609 comes to mind. You do need to pump up a supply 10+ V above your 12 Vdc though. \$\endgroup\$
    – winny
    Jan 26, 2021 at 13:46
  • \$\begingroup\$ @fifi_22 Can you suggest any such MOSFETs capable of controlling 60A through an H-Bridge intended to facilitate reversal of that current through coils; so generating very large voltage spikes? \$\endgroup\$
    – jeremiah
    Feb 8, 2021 at 15:51
  • \$\begingroup\$ @jeremiah These voltage spikes should be cached by flyback diodes placed antiparallel to the mosfets (I would also suggest snubbers across them). 60A is significant current, but depending of Your supply voltage, IRF1404 might be sufficient. Please provide more info (voltage, continous or just peak drive...) \$\endgroup\$
    – fifi_22
    Feb 8, 2021 at 16:00
  • \$\begingroup\$ If these values are those in question ( 12V, few Hertz frequency) You can use IRF1404 or similar fets with sufficient heatsink. \$\endgroup\$
    – fifi_22
    Feb 8, 2021 at 16:05

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