Overload detection circuit for UPC1237

Hello guys, I'm working on a loudspeaker protection design based on UPC1237. In it's datasheet there isn't provided any example of overload circuitry.
Designing such a circuitry isn't an easy task because there are lot of variables that should be considered in it since different amps work with different voltages and etc..

I have attached the M9 Amplifier schematic from "Analog Metric". this design benefits from upc1237 + overload detection circuit.

I want to know if it's possible to use and adopt the overload detector circuitry introduced in the M9 amp for another amplifier? say a MOSFET one like the Bora jagodic's designs.
 

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I' m bit confused about were those lines.....
Those lines represent the power amplifier output stage itself, not the protection circuit.

If you follow the chip's application notes, you will get a better idea of how its adapted to various power amplifiers and the proper specification of values to adapt to your application if suitable, and not some other amplifier with different ratings. NEC - datasheet pdf
 
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@KatieandDad, with R107 I'm guessing it sets trigger threshold. This combination sets it around 3A, IINM (0.6/0.22 * (16.5/15))

@Andreas, that circuit would trigger at a much lower threshold, would there not be a potential divider to adjust the threshold?

Have done some limited testing on the first circuit (the bad one) in an amp I am building. I agree that intuitively sensing current through both Re is better but even the other one worked. Haven't seen a situation where the circuit did not trip, including a shorted PNP transistor or a non-sensed pair shorting out. In every case the protection tripped.
 
@Andreas, that circuit would trigger at a much lower threshold, would there not be a potential divider to adjust the threshold?
It is a universal scheme. Threshold to arrange an additional resistor in parallel included C1.Calculation resistors watch SOA output transistors.

Have done some limited testing on the first circuit (the bad one) in an amp I am building. I agree that intuitively sensing current through both Re is better but even the other one worked. Haven't seen a situation where the circuit did not trip, including a shorted PNP transistor or a non-sensed pair shorting out. In every case the protection tripped.
Current sensor signal takes two output transistor - higher reliability.
 
Dear all, Thanks for the prompt replies.

How can I apply this ckt in chip amps(LM1875,3886, e.t.c.)?
@ Andreas AVM
Pls see attch., correct me if I'm wrong in understanding-
VT1, VT2 - o/p stage power transistors
VT3, VT5 (part no.?) - over load / S.C. current sense circuit.

@Ian Finch
I've built DC protection ckt using upc1237 & want to add overload / SC current sense capabilities. Being mathematically challenged I got stuck with formulas shown in datasheet.:eek: Surprisingly the ckt worked flawlessly!
 

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Dear all, Thanks for the prompt replies.

How can I apply this ckt in chip amps(LM1875,3886, e.t.c.)?
@ Andreas AVM
Pls see attch., correct me if I'm wrong in understanding-
VT1, VT2 - o/p stage power transistors
VT3, VT5 (part no.?) - over load / S.C. current sense circuit.

@Ian Finch
I've built DC protection ckt using upc1237 & want to add overload / SC current sense capabilities. Being mathematically challenged I got stuck with formulas shown in datasheet.:eek: Surprisingly the ckt worked flawlessly!
L100 and R111 for the L||R section of the Thiele Network are very high.

Have you rejected normal values for this amplifier?
 
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...For any application need?..
That's right to question. The whole basis of an overload protection circuits is that it must be adjusted precisely for the output stage it must protect. There are no typical values to try except by the given uPC1237 datasheet and application notes.

If someone claims their arrangement "works" by shutting down when the output is shorted, it means nothing if it is tripping at some fraction of the amplifier's rated power output. Unless the trip current is measured by some means, you can't know if it works perfectly or not without having followed the datasheet directions for your amplifier's design and output specifications.

The amplifier power rating is the basis of the values to be calculated which should maintain the output devices within their datasheet SOA curve limit at all times. Otherwise, you either have no protection or too little power output.:(