TPA3136D2: closing the loop with an external driver stage

Shawn Workman

Genius 16020 points

Part Number: TPA3136D2
Other Parts Discussed in Thread: OPA2990

Is it possible to close the loop on the TPA3136D2 around an external driver stage?

Can this be done with a PID loop control using an amplifier on each output of the driver stage?

Or could the information be fed back into the the OUTNL/PL and OUTNR/PR to regulate the loop?

ShawnPMP23173A(001)_Sch.PDF

over 4 years ago

0 Yanming Gong over 4 years ago

TI__Mastermind 19860 points

Hi Shawn,

In theory, the application is ok. TPA3136 is BD modulation.

Regards,

Derek

0 Shawn Workman over 4 years ago in reply to Yanming Gong

TI__Genius 16020 points

What is the best way to close the loop in this case?

Should it be differentially on the output back to the input or from the output back to OUT pins of the TPS3136?

0 Yanming Gong over 4 years ago in reply to Shawn Workman

TI__Mastermind 19860 points

Hi Shawn,

TPA316 is close loop and pre-filter feedback.

You can refer 9.2 Functional Block Diagram.

Regards,

Derek

0 Shawn Workman over 4 years ago

TI__Genius 16020 points

I understand that the TPA3136/7 is closed loop...but that does not help with this use case because of the external power stage. So I ask one more time, is there a way to close the loop around the external power stage back to the TPA3136/7 in this specific case?

Or should we look for another vender that can do this instead of the TPA3136/7?

Any recommendations for another Vendor that can do this?

0 Yanming Gong over 4 years ago in reply to Shawn Workman

TI__Mastermind 19860 points

Hi Shawn,

TPA3136 close loop is pre-feedback, it does not care external load and LC filter, etc.

You can see the block diagram, the feedback pin capture output pin. So in your case, TPA3136 does not care external power stage.

I do not know if it can help you.

Regards,

Derek

0 Shawn Workman over 4 years ago in reply to Yanming Gong

TI__Genius 16020 points

Derek,

My idea is to add an external amplifier circuit to close the loop around the external stage to input of the TPA3136/7 or OPA2990 in the circuit.

I am asking what is the best way to do this with an external amplifier and can it be done or will it not work due to the internal loop of the TPA3136/7 interfering with the outer external loop circuit?

Should I close the loop with the external amplifier to the input of the TPA3136/7 or the OPA input circuit?

Will the internal loop cause the external loop not to work?

Shawn

0 Yanming Gong over 4 years ago in reply to Shawn Workman

TI__Mastermind 19860 points

Hi Shawn,

I understand. If you want to add external circuit to TPA3136 internal loop, you should connect the external circuit output point to TPA3136 OUTL/R pins. Because TPA3136 capture output pins PWM output feedback. So I do not think the adding external circuit to TPA3136 internal loop application case is suitable.

+1 Shawn Workman over 4 years ago in reply to Yanming Gong

TI__Genius 16020 points

OK, this is helpful.

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TPA3136D2: closing the loop with an external driver stage