High Side Driver

Can you write something about this rather than just making a link-only post?

For how many years can you guarantee the above URL not to change?

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Music DIY Mailing List: http://www.kylheku.com/diy

Go to...

then click the S.E.D/Schematics button, and see a _somewhat_ complete listing of my posts (only about half of that page has been indexed).

Since it's my website... as long as I'm alive >:-}

Updated...

Now includes complete .CIR file (with all necessary device models), suitable for directly running in LTspice...

File/Open/HighSideDriver.cir

then select "Run" ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 

Sure, if you like flappy gates.

Also, who would buy an inductor when three BJTs does as well?

I did the inductor thing years ago, must've been like 2008ish. Plus a transformer:

But I'd much rather spend a few cents and as many watts with a CCS turnoff than a few bucks inductor. Better still, just use H bridge drive (TL598).

Tim

--
Seven Transistor Labs 
Electrical Engineering Consultation 

I guess you didn't observe the load current?

In general I'd guess your attention span is limited >:-} The need is for a high side driver, controlled by a 3.3V logic signal.

And the inductor is ~7 cents in the quantities used by my customer, and he's very cramped for space.

(In addition, schematic has been munged to hide details... customer only has +3.8V high-side supply, which must deliver 8 Amps to load with minimal drop.) ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 

I have a problem with Jim's pages, the lines are to thin to see, I suspect my reader, and will try adobe. How do I pull up associations? I've done it a dozen times but can't figure it out now. The reader I use is Foxit (I think, I find no identifying info) Thanks, Mikek

The free Adobe X Reader seems to work just fine. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 

Right click on the file and choose: 'Open With', then select 'Choose Program'. It will tell you what the default program is, and let you change it.

--
Anyone wanting to run for any political office in the US should have to 
have a DD214, and a honorable discharge.

How clever of you, to change the supply voltage to 12, to conceal from us that the actual voltage is 3.8.

Well done!

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John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Of course! I have to leave some tidbit for you to whine about. Otherwise your sycophants will realize you're an idiot, and we can't have that... at least not quite yet >:-} ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 

So, how did you calculate the R and L values? I assume you did it twice, once for 12 volts and once for 3.8.

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John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Think about it JOHN! Fundamentals! Sheeeesh!

I'm sorry! I apologize! You're a victim of your Tulane kindergarten education. My sincere apologies >:-} ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 

OK, you can't do it.

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John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Doesn't the magic smoke come out if there's even a tiny bit of current leakage draining away the voltage that L1 transferred to MN1's base? Or if the control signal to MN2 has a bit of a bounce? At least in your slightly obfuscated circuit, that would leave MN1 pumping out about 2 times its rated wattage.

PSpice needs a "circuit board in the tropics" mode.

Thanks, I had to save it before I could right click. I looks much better using Adobe than it does Foxit Reader. Anyone else have a problem seeing the lines... hmm, now after saving the file and opening it with Foxit, the schematic looks better with Foxit than Adobe. Any time I want to view Jim's schematics, I'll save it first. I think that was the solution. Mikek

For this application the drive is repetitive at ~2kHz square-wave. Think of it as a one-cycle boost: When MN2 turns off, 0.5*L*I^2 gets transferred to 0.5*C*V^2, turning on MN1. When MN2 turns back on, the L is recharged and the gate of MN1 is discharged.

Except for "tropics" mode ;-) I believe it will hold up for significantly lower rep-rates.

The link now includes a complete .CIR file suitable to run directly in LTspice. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 

0.5*L*I^2 = Qg*Vg (Qg = Total Gate Charge, from data sheet, at gate voltage, Vg)

Not "L = R^2 * C"

"Close to it" (pretty close actually) would be...

0.5*L*I^2 = 0.5*C*V^2

It's all about energy transfer from magnetic storage to capacitive storage... and boost converters rely on it. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 

[neglecting losses in diode and resistor, I'll include that RSN, otherwise someone will have another hissy fit :]

...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 

Good grief! Do the algebra!

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John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Thank You! I had the same problem. After reading your post, I saved it then opened it. Bingo! Now it's readable.

Ed