Need to identify unknow parts in a IC schematic

[gaetan8888]

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

[djoffe]

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.

[gaetan8888]

Hello

So, R6 resistor do just have a center tap ?

Thank

Bye

Gaetan

[djoffe]

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.

[gaetan8888]

Hello

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

Thank

Bye

Gaetan

[gaetan8888]

Originally Posted by djoffe

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

[scott wurcer]

Originally Posted by gaetan8888

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

[gaetan8888]

Originally Posted by scott wurcer

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