Determining current limit - diyAudio
 Determining current limit
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 30th August 2011, 08:48 PM #1 diyAudio Member   Join Date: Oct 2004 Location: Denmark Determining current limit If you have 2 pairs of 16A, 250W TO-3 Lateral FET's with a SOA curve showing a maximum DC current of around 6A at 42V Drain-source what would a reasonable current limit be set to? There is no 100ms or 10ms SOA plot for the Semelab BUZ line of FETs that I'm planning to use. I know they are Laterals so they have their own "built in" current limiter due to their negative temp co but in my case I am using flying catch diodes to limit the maximum Vgs. Which of cource means that I also have a current limit. Double the amount of flying catch didoes in the diode string from 1 to 2 which gives me a current limit of around 12-13A so that is very close to their specified DC current in the SOA plot. However, for music would it not be reasonable to set the current limit a little higher, say 20A instead? Just needs another pair of diodes and I'm at 20A. 20A with a music signal should be well within the limit of 2 pairs of 16A, 250W, TO-3 Laterals. Any thoughts and/or suggestions? Last edited by Neutrality; 30th August 2011 at 08:51 PM.
 31st August 2011, 06:12 AM #2 diyAudio Member     Join Date: Feb 2001 Location: USA Most laterals are about 1A per volt of gate voltage. Clamp the gates at 10V and use a thermal cut-out at 85°C, that should be enough. __________________ Candidates for the Darwin Award should not read this author.

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