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Forum Index : Electronics : How’s this for a high-side NMOSFET driver

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LadyN

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Joined: 26/01/2019
Location: United States
Posts: 408
Posted: 01:33am 15 May 2019
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There's some renewed interest here with people considering other flybacks that could be made to run at a lower startup voltage of around 48v to drive high-side NMOSFET.

I discovered this one:

https://m.eet.com/media/1135542/15729-52704di.pdf

Scroll to page 100 : Circuit makes simple high-voltage inverter

what do you all think?
 
LadyN

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Joined: 26/01/2019
Location: United States
Posts: 408
Posted: 01:34am 15 May 2019
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Errata in the comments here: https://www.edn.com/design/power-management/4333044/Circuit-makes-simple-high-voltage-inverter
 
LadyN

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Joined: 26/01/2019
Location: United States
Posts: 408
Posted: 08:08pm 12 Jul 2019
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Inputs anyone?
 
Solar Mike
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Joined: 08/02/2015
Location: New Zealand
Posts: 1138
Posted: 04:20am 13 Jul 2019
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Interesting take on a bootstrap idea to get a high side drive; OK I guess for high voltages and low currents, not really useful for 50v powered inverters, big power loss in D4,6 diodes; driver is not going to work with multiple paralleled mosfets, also it causes cross-conduction in the two mosfets. Driver stage is old tech and better replaced by modern high current driver chips.

There are other psu's available Example Link that are designed for 50-70 volt input if one is worried about getting the $2 versions to work, just have to pay more...

It would be a good project to make a small flyback or push-pull converter that ran from 24 to 70 volts and had multiple isolated 12/15v outputs of 3-5 watts each.

Cheers
Mike
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 04:45am 13 Jul 2019
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It all becomes much easier, and a lot more efficient if the inverter is designed to run at 100v dc, rather than at 50v dc.
Cheers,  Tony.
 
Tinker

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Joined: 07/11/2007
Location: Australia
Posts: 1904
Posted: 09:28am 13 Jul 2019
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  Warpspeed said   It all becomes much easier, and a lot more efficient if the inverter is designed to run at 100v dc, rather than at 50v dc.


Yes, but not cheaper as one then requires twice the number of battery cells .
Klaus
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 12:08am 14 Jul 2019
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  Tinker said  
  Warpspeed said   It all becomes much easier, and a lot more efficient if the inverter is designed to run at 100v dc, rather than at 50v dc.


Yes, but not cheaper as one then requires twice the number of battery cells .

With twice as many cells, each cell only has to have half the amp hour capacity and is half the size.
Cost difference ends up being absolutely minimal.

What does become more complicated will be the cell voltage monitoring and cell balancing boards. They obviously use more parts and cost more.

But then you save on the cost of the wiring as the current will be only half.

It all balances out, and I have never regretted going to a 100v system.
Cheers,  Tony.
 
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