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Re: [TCML] sg3525


There are several alternatives. 
1. Use a International Rectifier IR2153D or IR21531D chip. 
They are used in plasma globe drivers, are half bridge and with 
level shift 600V drivers will do almost everything you need, in an 8 pin chip. 
They were originally designed for the CCFL driver market. 



Although I have not built it, this chip family could be easily used to build a 
HB variable frequency power driver for isolated power sources, small induction 
heaters or SSTC (not DRSSTC's). Auxiliary part count would be very low as 
well, compared to alternative circuits. The IRS21531D is the part you would 
want in a through hole DIP8 package. Digikey stocks them at less then $3.00 
US each. 


You would want to use the IRS part versus the original IR part, newer 
part has bootstrap housekeeping circuitry integrated into die, and reduces 
the further external parts to get your circuit running. 

A TI/Unitrode UCC3808 is current mode push pull PWM IC that I have used, driving a 
toroidal transformer (and gate drive transformer) to produce +/- 15VDC PS with up 
1kV AC/DC isolation for Toshiba TLP250 isolated IGBT/FET drivers. Chip is 
very simple (had running with less then 6 passive parts other then chip, at 150kHz) 
and chip has fairly good drive capability (500mA source, 1A peak sink respectively), 
so you can direct drive a gate drive transformer for isolated PS effectively. Has typical 
switch mode features (soft-start, current limiting etc.); I just ran my circuits open loop 
and let it rip, ran fine. 


Digikey also stocks, at less then $3.00 also (must compete with IRS21531D ;^D ) 


Dave Sharpe, TCBOR/HEAS 
Chesterfield, VA USA 

----- Original Message ----- 
From: "Scott Bogard" <sdbogard@xxxxxxxxx> 
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx> 
Sent: Wednesday, April 1, 2009 6:16:29 PM GMT -05:00 US/Canada Eastern 
Subject: [TCML] sg3525 

Greetings all, 
I am looking into an IC driven flyback driver (as opposed to the 
self resonant topology.) I am thinking about the sg3525, I didn't 
want to go with the 555 because everybody uses it and I want to make a 
half bridge or a pushpull (for better power throughput at frequencies 
other than perfect resonance.) I found this IC and it looks very 
promising, no need for a gate transformer or other such things; but I 
have no idea how to hook it up for reasonable frequency ranges 
15-100kHz, or what to change to vary the duty cycle, most applications 
I see for this chip use low frequency output for inverters and such. 
I am told this chip can also be easily modulated to switch between 
frequencies which would be cool for plasma stuff. I found a data 
sheet but it isn't very clear, and I was hoping somebody out there had 
experimented with one of these and could shed some light on how to 
wire it. Thanks. 

Scott Bogard. 
the data sheet 
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