TPA3255EVM: TPA3255

ilya tashaev

Part Number: TPA3255EVM
Other Parts Discussed in Thread: TPA3255, , TPA3245

Hello

i'm using the TPA3255 AMP, and i would like to implement the TPA325x Post-Filter Feedback to it as described in the (SLAA788A - Application Report)

now as i see in the TPA3255EVM schematics has a Zobel of Capacitors (C26, C37. C45, C61) and Resistors (R11, R14, R18, R22).

also in the TPA325x Post-Filter Feedback has a Zobel of Capacitors (Cz) and Resistors (Rz) added (C77, C78. C79, C80) and (R53, R54, R55, R56).

my question is :

1) do i need to cancel (remove) the Capacitors (C26, C37. C45, C61) and Resistors (R11, R14, R18, R22), and FIT ONLY the TPA325x Post-Filter Feedback Cz and Rz (C77, C78. C79, C80) and (R53, R54, R55, R56) ?

2) are there any other modifications that needs to be done that are not described in the TPA325x Post-Filter Feedback ?

3) are there any values, parts or revisions update as of 2018 ?

attached the schematic and TPA325x Post-Filter Feedback...

thanks

thereTPA324x and TPA325x Post-Filter Feedback.pdf TPA3255EVM Schematic (Rev. A).pdf

11 months ago

0 Luis Fernandes de Pina 11 months ago

TI__Genius 14640 points

Hello Ilya,

Yes it would be best to not have the zobel there
Note for the TPA3255, the PFFB tests were done on a custom board so the EVM does not have all the available footprints to implement PFFB with the circuit shown in the app note, The TPA3245 does however
No updates

best regards,
Luis

0 ilya tashaev 11 months ago in reply to Luis Fernandes de Pina

Prodigy 115 points

Hi Luis

thank you for your reply,

i just want to make sure so i remove (C26, C37. C45, C61) and (R11, R14, R18, R22) from the eval board

and fit (C77, C78. C79, C80) and (R53, R54, R55, R56) right ?

0 Shadow He 11 months ago in reply to ilya tashaev

TI__Mastermind 40190 points

Hi Ilya

The Cz and Rz (C77, C78. C79, C80) and (R53, R54, R55, R56) is also not necessary. As Luis mentioned EVM doesn't leave space for PFFB. Normal using doesn't need to add Zobel circuit.

0 ilya tashaev 11 months ago in reply to Shadow He

Prodigy 115 points

Hi Shadow

you didn't understand the question ....

0 Luis Fernandes de Pina 11 months ago in reply to ilya tashaev

TI__Genius 14640 points

Hello Illya,

(C26, C37. C45, C61) and (R11, R14, R18, R22) can be removed
The EVM does not have all the necessary connections for PFFB

Above is what's on the TPA3255EVM

Above is the PFFB implementation necessary

Above is the PFFB implementation outlined in the Application note

(C77, C78. C79, C80) and (R53, R54, R55, R56) is just another Zobel network to help EMI, it's not the PFFB passives

best regards,
Luis

0 ilya tashaev 11 months ago in reply to Luis Fernandes de Pina

Prodigy 115 points

Hi Luis

yes i know about these 3 parts that needs to be added, will add them in the new pcb design for the testing will solder them manually.

so if i understand you correctly i need to keep the (C26, C37. C45, C61) and (R11, R14, R18, R22) Zobel networks when implementing PFFB ?

0 Luis Fernandes de Pina 11 months ago in reply to ilya tashaev

TI__Genius 14640 points

Hello Ilya

(C26, C37. C45, C61) and (R11, R14, R18, R22) can be removed. It's for EMI purposes not part of the Post-Filtered Feedback Network, but it shouldn't impact the PFFB topology much.

best regards,
Luis

0 ilya tashaev 11 months ago in reply to Luis Fernandes de Pina

Prodigy 115 points

Hi Luis

ok i see i will keep them and also add the PFFB implementation...

so can i be relax that they will not interfere with PFFB additions ?

0 Luis Fernandes de Pina 11 months ago in reply to ilya tashaev

TI__Genius 14640 points

Hello Illya,

that is correct.

best regards,
Luis

Amplifiers

Amplifiers forum

TPA3255EVM: TPA3255