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Comparison of power switches for least on voltage drop

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ZeroResistance:
I'd like to know which power switch among
1. Transistor
2. IGBT
3. Mosfet
4. Triac
would have least forward voltage drop when used as a power switch in power applications at voltages in the range of 300 to 500VDC.
From my understanding a Mosfet should have been capable of this, but from what I've seen Power mosfets generally have a higher Rds on.

Thanks in Advance.

Kleinstein:
A triac is not really working with DC - it needs some extra tricks to turn them off. It is not that good with voltage drop either.

IGBTs have a significant minimum drop ( > 1 V), similar to the triac, even at low currents. It might still be acceptable at a relatively high voltage (e.g. > 600 V).

For MOSFETs the voltage drop is just from R_on. So it depends on the current and size of the MOSFET. It can be very low drop with a large one, but also higher than that of a IGBT with a rather small one optimized for high voltage switching. R_On goes up with higher voltages, so that very low R_on may not be practical.

BJT Transistors have a small fixed minium drop of around 50-100 mV combined with on Resistance. Depending on the size it can be reasonably low, even at high voltage.

6PTsocket:
IGBT's are used in high power situations. Where I worked, a bank if them was used to switch a long string of big motors. The hybrid design allows fast switching so the switch does not dissipate a lot of heat during the the transition.

Sent from my SM-G900V using Tapatalk

ZeroResistance:

--- Quote from: Kleinstein on October 06, 2018, 08:08:01 am ---A triac is not really working with DC - it needs some extra tricks to turn them off. It is not that good with voltage drop either.

IGBTs have a significant minimum drop ( > 1 V), similar to the triac, even at low currents. It might still be acceptable at a relatively high voltage (e.g. > 600 V).

For MOSFETs the voltage drop is just from R_on. So it depends on the current and size of the MOSFET. It can be very low drop with a large one, but also higher than that of a IGBT with a rather small one optimized for high voltage switching. R_On goes up with higher voltages, so that very low R_on may not be practical.

BJT Transistors have a small fixed minium drop of around 50-100 mV combined with on Resistance. Depending on the size it can be reasonably low, even at high voltage.

--- End quote ---

It would be interesting to know the voltage drop of the Triac for AC systems, from hat I've read they have round 1 to 2V drop.
Also interesting that BJT's can acheive low drops, are there any good devices at > 400V that have a low saturation volateg. in the range you mentioned (50 to 100mV) and reasonably priced.
High voltage mosfets seem to have larger Rds on and the ones that have low Rds on for higher voltages need you to spend more money.

ZeroResistance:

--- Quote from: 6PTsocket on October 06, 2018, 09:23:36 am ---IGBT's are used in high power situations. Where I worked, a bank if them was used to switch a long string of big motors. The hybrid design allows fast switching so the switch does not dissipate a lot of heat during the the transition.

Sent from my SM-G900V using Tapatalk

--- End quote ---
I guess they don't dissipate heat during the transition. But when used as a static switch, it might dissipate considerable power, looking at the high voltage drop that they have,based on what Kleinstein pointed out.

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