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Old 4th March 2012, 12:24 AM   #1
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Default Need to identify unknow parts in a IC schematic

Hello

I want to simulate this SG3524 inside schematic with LTspice or Tina-Ti, but there is parts that I can't identify, it's Q6 and Q58, R6 and R40, we can see few others similar parts in the schematic.

Can you tell me what are those parts and if I can use a combination of standard bjt transistors to do an equivalence of Q6 and Q5 ?

I include images of those parts, the SG3524 inside schematic and the SG3524 block diagram.

Thank

Bye

Gaetan
Attached Images
File Type: gif unknow parts types.gif (6.5 KB, 125 views)
File Type: gif SG3524-internal schematic-.gif (100.6 KB, 127 views)
File Type: gif SG3524-block diagram.gif (37.0 KB, 124 views)

Last edited by gaetan8888; 4th March 2012 at 12:30 AM.
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Old 4th March 2012, 04:07 AM   #2
djoffe is offline djoffe  United States
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think of the transistor with multiple collectors as multiple transistors where base and emitters are common, but the collectors are separate.

The resistors with the lines are still resistors, although they're usually made in a way that has a fairly high voltage coefficient, so the circuits typically make use of matching, or the resistors being rather uncritical in their value.
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Old 4th March 2012, 04:16 AM   #3
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Hello

So, R6 resistor do just have a center tap ?

Thank

Bye

Gaetan
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File Type: gif R6.gif (578 Bytes, 107 views)
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Old 4th March 2012, 04:23 AM   #4
djoffe is offline djoffe  United States
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no center tap. the symbol actually says a distributed RC structure, but no additional dc connections except the two normal terminals at the ends of the resistor.
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Old 4th March 2012, 04:37 AM   #5
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Hello

But why there is a connection from that R6 center to Q76 emiter and Q13 base ?

Thank

Bye

Gaetan
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File Type: gif R6 connection.gif (4.1 KB, 87 views)
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Old 4th March 2012, 06:28 AM   #6
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Quote:
Originally Posted by djoffe View Post
think of the transistor with multiple collectors as multiple transistors where base and emitters are common, but the collectors are separate.
Hello

Is it like in the image I include ?

Thank

Bye

Gaetan
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File Type: jpg transistors.jpg (43.9 KB, 79 views)
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Old 4th March 2012, 12:31 PM   #7
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Quote:
Originally Posted by gaetan8888 View Post
Hello

So, R6 resistor do just have a center tap ?

Thank

Bye

Gaetan
No that could be the back connection. An n+ resistor is made with emitter matierial and has a base emitter breakdown possible so you must take care in connecting the back (p) to a potential that avoids this or they are pinch resistors which are like FETs operated in triode region where that little bar is the "gate". Very nonlinear but the only way to easily get high value resistors in olden times but are still used in some places. The comment about the multi-collector pnp's is correct exccept that they can have high level injection and there is a parasitic collector to the substrate, best to just use the parallel devices and hope for the best.

http://www.mos-ak.org/montreux/poste...s_MOS-AK06.pdf
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Last edited by scott wurcer; 4th March 2012 at 12:41 PM.
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Old 4th March 2012, 04:15 PM   #8
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Quote:
Originally Posted by scott wurcer View Post
No that could be the back connection. An n+ resistor is made with emitter matierial and has a base emitter breakdown possible so you must take care in connecting the back (p) to a potential that avoids this or they are pinch resistors which are like FETs operated in triode region where that little bar is the "gate". Very nonlinear but the only way to easily get high value resistors in olden times but are still used in some places. The comment about the multi-collector pnp's is correct exccept that they can have high level injection and there is a parasitic collector to the substrate, best to just use the parallel devices and hope for the best.

http://www.mos-ak.org/montreux/poste...s_MOS-AK06.pdf
Hello Scott

In my LTspice simulation, can I replace all those n+ resistor by standard resistors of sames values, if not, what can I use ?

And in my LTspice simulation, I will replace all the multi-collector pnp's by parallel devices.

Thank you

Bye

Gaetan

Last edited by gaetan8888; 4th March 2012 at 04:22 PM.
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