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Author Topic: Do dual mosfets max VDS doubled, in the back to back connection as a switch ?  (Read 850 times)

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Offline BravoVTopic starter

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Do dual mosfets max VDS doubled, in the back to back connection as a switch ?
« on: December 19, 2018, 06:57:20 am »
With identical mosfets, does the maximum VDS doubled at the switched line ?

For e.g. each max breakdown VDS = 100V, with this configuration will it become 200V ?

Assuming the gate driver is fully isolated, like using photovoltaic MOSFET driver.

« Last Edit: December 19, 2018, 07:02:19 am by BravoV »
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Offline capt bullshot

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Re: Do dual mosfets max VDS doubled, in the back to back connection as a switch ?
« Reply #1 on: December 19, 2018, 06:59:33 am »
No, it does not.
One of the MOSFETs is reverse biased in this configuration, so its internal diode is conducting and pushing all the voltage drop to the other one.
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Offline BravoVTopic starter

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Re: Do dual mosfets max VDS doubled, in the back to back connection as a switch ?
« Reply #2 on: December 19, 2018, 07:15:57 am »
Quote from: capt bullshot on December 19, 2018, 06:59:33 am
No, it does not.
One of the MOSFETs is reverse biased in this configuration, so its internal diode is conducting and pushing all the voltage drop to the other one.

Ah, thanks, forgot the body diodes at both fets.  :palm:

So the max breakdown simply = (A single VDS) + (Single body diode VF) ?

Back to drawing board to find suitable MOSFETs.
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Offline capt bullshot

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Re: Do dual mosfets max VDS doubled, in the back to back connection as a switch ?
« Reply #3 on: December 19, 2018, 07:22:09 am »
Or even simpler just the single VDS, since the body diode VF usually is significantly lower than the breakdown voltage, especially as long as it isn't carrying current.
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Offline BravoVTopic starter

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Re: Do dual mosfets max VDS doubled, in the back to back connection as a switch ?
« Reply #4 on: December 19, 2018, 07:23:24 am »
Yeah, noted, as the VF is minuscule compared to VDS, again, thanks.
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