Bootstrap high side driver IC's are no good?

[grizedale]

In the following article, Dr Ray Ridley, the world's pre-eminent SMPS designer, slates the use of Bootstrap High Side Driver chips such as NCP5181.

Dr Ridley states that with mains voltage SMPS's, its always preferable to use gate drive transformers.

This statement can be found in the first page of the following article........the text is at the top right hand corner, just above Figure 1.
Gate Drive Design Tips - Ridley

How can Dr Ridley make such a sweeping statement?
-and is he right?

NCP5181 DATASHEET
https://www.onsemi.com/pub_link/Collateral/NCP5181-D.PDF

 

[dick_freebird]

This looks like pure opinion to me, other than that a transformer
is going to be a more reliable isolator than an IC. -He- prefers to
have total control and flexibility. -You- may prefer to not have
to roll your own anti-shoot-through timing, have built-in features
and so on.

Now I'm also not too sure about the "world's pre-eminent SMPS
designer" bit. Most avidly self-promoting, perhaps. But somebody
who spends all their time advertising and teaching courses probably
isn't "living the life" the way a lot of power supply designers do
day in, day out.

 

[grizedale]

Im glad to hear you say that because pulse transformers are a pain.

they give you a fet drive voltage which varies with duty cycle......or , if you put in a DC restoration circuit to stop this, then you end up with the problems stated in the above article where it may blow up when the PWM controller stops...due to the fet being turned on spuriously.

 

[mtwieg]

In the following article, Dr Ray Ridley, the world's pre-eminent SMPS designer, slates the use of Bootstrap High Side Driver chips such as NCP5181.

Never heard of him.

Dr Ridley states that with mains voltage SMPS's, its always preferable to use gate drive transformers.

It's surprising to hear such a categorical, sweeping statement from an engineer, especially in the face of the thousands of other engineers who don't follow his advice.

This statement can be found in the first page of the following article........the text is at the top right hand corner, just above Figure 1.
Gate Drive Design Tips - Ridley

I don't see how bootstrapping drivers allow for less control of the circuit. Sounds like nonsense. Lack of isolation is a given, but he's not surprising anyone there. Statements on reliability can't just be made offhand. You have to back up such claims with more than a one-liner.

There are circumstances where GDTs won't be feasible, such as high frequency converters (due to leakage inductance). And there are lots of cases where complete isolation isn't necessary (many DC-DC converters). And there are applications where GDTs work great (high power full bridge converters, etc). This article isn't worth being branded "right" or "wrong," it's too vague to be given specific responses. Except that "lack of control" bit. I'm pretty sure that's wrong.