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Design >> High-Power Design >> High Voltage Switch
https://designers-guide.org/forum/YaBB.pl?num=1413824174

Message started by bki on Oct 20^th, 2014, 9:56am

Title: High Voltage Switch
Post by bki on Oct 20^th, 2014, 9:56am

Hi,

i need a switch that connects 150V to the load. That means, if the switch is closed i have 150V on the drain side and 150V on the source side.

Any idea, how can i realize this switch? Maybe is there a solution available on the market?

As far as i know, the most Power MOSFETs only accept such high voltages only on the drain sides but not on the source sides.

Please help!

Title: Re: High Voltage Switch
Post by loose-electron on Oct 20^th, 2014, 4:34pm

discrete transistors here right?

what is important is the

max Vds
max Vgs

and depending on the architecture of the transistors (a lot of discrete MOSFET's are not symmetric in their doping profiles)

sometimes max Vdg

give us a simple drawing of what you are trying to do and perhaps we can help.

Title: Re: High Voltage Switch
Post by bki on Oct 21^st, 2014, 12:39am

Attached is the picture.

The problem is, i have a gate voltage of 5V. So, if Vgs is maximum 20V for example, it means that on the source side can be maximum 25V. correct?
So i would need a transistor that has Vgs=155V, if the source should withstand 150V. correct?
Does anyone know a suitable solution?

Title: Re: High Voltage Switch
Post by boe on Oct 21^st, 2014, 8:54am

bki,
assuming Vcap < Vboost, the standard solution is a "floating voltage source", that drives the gate 5V above the source.
- B O E

Title: Re: High Voltage Switch
Post by loose-electron on Oct 21^st, 2014, 11:35pm

look at the architecture associated with "high side driver circuits" commonly used in half bridge drivers and similar power transistor control circuits.

Title: Re: High Voltage Switch
Post by bki on Oct 22^nd, 2014, 2:11am

Vcap is -40V and should become 150V when the switch is closed.
Isn´t there a simple solution to connect the 150V with the output?
The High Side MOSFET concept seems not to be a solution.

Title: Re: High Voltage Switch
Post by loose-electron on Oct 28^th, 2014, 10:19am

loose-electron wrote on Oct 21^st, 2014, 11:35pm:

look at the architecture associated with "high side driver circuits" commonly used in half bridge drivers and similar power transistor control circuits.

Start by putting the above into search.