Hi there.
I have an existing mosfet amplifier design, and I would like to add some current protection to the design. Can anyone point me to a page or 2 where I can learn more about how to do this?
Also, I would like to know abit more about adding more power transistors in parallel. Is it always a simple case of just adding a couple more of them in parallel, each with their own gate driving resistor?
In the case of adding more power transistors to a current-limited bipolar design, how do I go about that? I have seen designs where the current through one of the pairs is measured and this signal is used for current limiting purposes, while the rest of the pairs only have each their own emitter resistor. Is this the way to go?
Why do the current limiting transistors always have a diode and a resistor from their base to the output? The resistor I understand, forms part of a voltage devider to set the current limiting point. Is the diode there to "enable" the current limiting of each side only during it's active cycle?
Many question I have asked. I now leave it to the masters of audio to come and educate the layperson..
regards
Carel
I have an existing mosfet amplifier design, and I would like to add some current protection to the design. Can anyone point me to a page or 2 where I can learn more about how to do this?
Also, I would like to know abit more about adding more power transistors in parallel. Is it always a simple case of just adding a couple more of them in parallel, each with their own gate driving resistor?
In the case of adding more power transistors to a current-limited bipolar design, how do I go about that? I have seen designs where the current through one of the pairs is measured and this signal is used for current limiting purposes, while the rest of the pairs only have each their own emitter resistor. Is this the way to go?
Why do the current limiting transistors always have a diode and a resistor from their base to the output? The resistor I understand, forms part of a voltage devider to set the current limiting point. Is the diode there to "enable" the current limiting of each side only during it's active cycle?
Many question I have asked. I now leave it to the masters of audio to come and educate the layperson..
regards
Carel
Try this link for an example of a multislope protection circuit. http://www.sealelectronics.com/kits/images/OPTI1001.pdf
You probably have to use different values with different output components and topology but the idea remains the same. \
You can also look at the zener + GP diode in ESP's Project 101. This is pretty much straight from the Exicon app-note (or other sources) This is allegedly too slow if you use double-die MOSFETS and I've read that while it protects the devices, when it activates it may (will?) blow the rail fuses.
You probably have to use different values with different output components and topology but the idea remains the same. \
You can also look at the zener + GP diode in ESP's Project 101. This is pretty much straight from the Exicon app-note (or other sources) This is allegedly too slow if you use double-die MOSFETS and I've read that while it protects the devices, when it activates it may (will?) blow the rail fuses.
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