If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #3900
Joined: Thu May 19 2011, 08:28PM
Location:
Posts: 600
In the past I've built plenty of inverters driven by bootstrapped high side type drivers successfully. For the past few days I've been trying to get the driver on my breadboard working properly, but its being stubborn. I'm using the fan7392 driver, and the high side output just isn't driving...
I've gone through everything I've thought of, so any new thinking would help. The inputs are fine, perfect alternating square pulses from an sg3525, no problem there. The low side is fine, and when the high side section is hooked up directly to vcc and gnd it outputs just like a low side driver. So there aren't any internal issues. When hooked up as indicated in the data sheet, the simplest of implementations, the entire high side section(all the pins) go to vcc. But no output.
I've swapped diodes and caps multiple times, and I'm convinced everything is fine. I even tried different driver ic's and they all give me the same issue.
Registered Member #3900
Joined: Thu May 19 2011, 08:28PM
Location:
Posts: 600
Yes, and for getting the circuit working none of it should really matter other than the sizing of the bootstrap capacitor. Uvlo was another concern, but I raised the supply to just under 20v to be sure. I have no series resistor. I have no need to limit inrush current at this point, and in the past the circuit has worked fine without it.
Registered Member #3900
Joined: Thu May 19 2011, 08:28PM
Location:
Posts: 600
Yep, I have both fets floating for test. The high side vcc, gnd, and the output almost look like common mode noise from the low side, but its not. There is a square wave of ~1v pk-pk floating at 18v. It's common between all high side pins, but the vb pin is a volt or two higher than vs and vo.
Registered Member #103
Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845
I know you said you'd raised the supply voltage to make sure you're over any uvlo thresholds, but try probing directly across the bootstrap capacitor (Cboot) if you haven't already, to make absolute sure the bootstrap operation is working. That chip appears to have separate undervoltage shutdowns for high and low side, and Cboot needs to be at about 10 volts to work.
Only suggesting this because I've wasted about half a day before on a very similar problem, and from what you've described this is about all it can be!
Registered Member #146
Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055
[blockquoteYep, I have both fets floating for test.[/blockquote]
That sounds like the problem.
You need to have the fets connected as a half-bridge, and you need to turn on the low side fet first to charge the boostrap capacitor for the high side driver. I cant tell if this is clearly understood by you or not but it sounds like it fits the bill for explaining your problem.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
High side Ic problems
