LM4702 simulation in TINA - diyAudio
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Old 13th April 2013, 05:29 PM   #1
danny92 is offline danny92  Portugal
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Default LM4702 simulation in TINA

Hi everyone,
I'm trying to simulate a LM4702 based power amplifier, but using the TI models I don't have any current bettwen the source and sink pins, and I think it should have at least 1 mA or more, what's happening?

Best regards,
Daniel Almeida
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Old 13th April 2013, 05:41 PM   #2
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You should put the question to TI in their "EE" forum. They're not too interested in sharing the innards of their models -- but you can get a glimpse from the simplified schematic of some of their driver chips.
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Old 13th April 2013, 05:42 PM   #3
danny92 is offline danny92  Portugal
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Thank you for your help
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Old 14th April 2013, 12:17 PM   #4
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Added some amp meters to the reference design, does it look ok?

Click the image to open in full size.

Jaz
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Old 15th April 2013, 01:08 PM   #5
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The TI SPICE models of a number of the Nat Semi parts (especially their integrated power amp chips) are very incomplete. I haven't looked at the LM4702 though.

BTW, I trust you will replace the generic NPN and PNP transistors with properly-modelled items?

Your ammeters will show the base current flowing into and out of the transistors. I normally use the 'current arrow' component to keep the schematic clean, it gives just the same information as the ammeter.
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Old 16th April 2013, 08:43 AM   #6
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Did not mess with the transistors at all... Only added the amp meters to see if there is current flow, since the OP said he was not getting any source to sink current when he ran the sim. Thanks for the tip on the current arrow - still learning to use TINA-TI...

Jaz
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Old 16th April 2013, 09:54 PM   #7
danny92 is offline danny92  Portugal
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Thank you for your help,

The problem is the almost complete absence of DC current between the source and sink pins. So I can't use correctly the VBE multiplier to achieve the desired levels of quiescent current passing thru the conduction channel of the output MOSFET devices.
:S
AC is fine.


Best regards,
Daniel Almeida

Last edited by danny92; 16th April 2013 at 09:56 PM.
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