What's the difference between MOSFET high side and low side switching?

datapersada said:

Thamid, please see my Sony schematic and my question are:
1. Which mosfet is on low and on high (PQ7 & PQ11, PQ8 & PQ12)?
2. From which mosfet allways on 5v and allways on 3.3v?

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joelyoung said:

Hello my friend such a long time you have not replied to my message. Anyway I reach a little further with the inverter now but the problem I am having is the 170v is falling off with a load as little as 9 watts please give me sugestions as how to check the feed baack loop on the sg3525 circuit. Thank you. Waiting your reply

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Tahmid said:

Hi,
High side switching is required when your MOSFET is in high side configuration. This is when the drain is connected to +ve and load is taken through source to ground. As a result source has no direct connection to ground. Here when +ve is 200v, your VGS has to be 200+10 = 210V because source is not directly connected to ground, and when on has a potential of 200v.
Low side is where load is taken from drain and source is connected to ground. Here, VGS is always eg 10v as source is connected directly to ground.

In bridge circuits you need both high and low side switching.


Hope this helps.
Tahmid.

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