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TPA3255: NEED Design for 2 x tpa3255 in PBLT mode

Rajesh Ramesh
Prodigy 130 points
Part Number: TPA3255
Other Parts Discussed in Thread: TAS5630

Dear Sir

We working for the client they need to design 2 x tpa3255 in PBLT mode with SYNC with 300W o/p with THD for 0.01

we have already done the Design but we getting issue 

We using 2 x tpa3255 for 175W o/p each in PBLT mode

but when we check the output of  2 tpa3255 working properly for around 70W  after that the Master get Reset (Every time)

Slave working properly & supporting till 170W .

Kindly support for Design to sync 2 x tpa3255 in PBLT mode.

Regards

R.Rajesh

rramesh@hubbell.com

rameshrajesh321@gmail.com

  • 0
    TI__Expert 6195 points
    Hi R. Rajesh,

    Let me verify that I understand your issue:
    You system has 2 x TPA3255 both in PBTL configuration, one as slave and one as master. When you increase the input signal, the master shuts down at around 70W, however this issue is not seen with the slave device. The slave device operates to 170 W.

    I think it will be necessary for me to review your schematic in order for me to find the issue. One possible issue is if you have pullup resistors on Channel C and D. This has caused issues for customers in the past – see this E2E forum here. e2e.ti.com/.../2110084

    Regards,

    Dan
  • 0 in reply to Dan Kisling
    Prodigy 130 points

    Dear Dan

                                 I have attached the our Design Below But there is Some Changes have be done.

    As you mentioned Need to Change Pull up & other in channel C & D Have been Done & its is Shorted to GND 

    even though the Same Problem is Happening again

    now the THD is 3% at 170W (Previously around <1% THD)

    Kindly Suggest any CounterMeasure

    Regards

    R.Rajesh

  • 0 in reply to Rajesh Ramesh
    TI__Expert 6195 points

    Hi R. Rajesh,

     

    There are a few things I see in the schematic I think will cause issues.

    1. OSC_IOP and OSC_ION should not have 100k resistors. They should be connected directly to the other device.

    2. M1 and M2 should not be connected through 10k resistors.

    3. For PBTL, input C and D should be tied directly to ground.

    4. FREQ_ADJ on the slave device should be connected directly to DVDD, not through a 10k resistor.

     

    To check over your design, you can use our EVM schematic as a guide found here. http://www.ti.com/lit/df/slar129a/slar129a.pdf

    You can also use our Setup Guide and Configuration Tool.

    http://www.ti.com/lit/zip/slac733

     

    The schematic is somewhat hard to read, but it looks like PVDD=35V for your design. The TPA3255 will be limited on output power depending on the supply voltage and load. See Figure 23. Output Power vs Supply Voltage in 7.11 Typical Characteristics, PBTL Configuration.

    http://www.ti.com/product/TPA3255/datasheet/specifications#SLASE408255

     

    Let me know if any of the above fixes work.

    Best regards,

     

    Dan

  • 0 in reply to Dan Kisling
    Prodigy 130 points

    Dear Dan

    thanks for the Valuable Suggestion 

    I have Done the Changes as you Suggested Now its Working For 300W

    But the THD of the System in 300W is around 2.4%

    Kindly Suggest any Counter Measure for this Issue .

    Regards

    R.Rajesh

  • 0 in reply to Rajesh Ramesh
    TI__Expert 6195 points

    Hi R. Rajesh,

     

    Looks like we are getting somewhere! Are the master and slave device both reaching this THD+N level at 300W?

     

    What load are you driving with the TPA3255 in PBTL? What voltage are you using for PVDD? You can see the power output of a 4 ohm load for PVDD = 51V in the datasheet. See Figure 19. Total Harmonic Distortion+Noise vs Output Power. It looks pretty close  to 2.8% for 300W.

    http://www.ti.com/product/TPA3255/datasheet/specifications#SLASE408255

     

    Best regards,

    Dan

  • 0 in reply to Dan Kisling
    Prodigy 130 points

    Dear Dan

    We coupling the 2 x tpa3255 using Transformer & loading with 33.3ohms Resistor

    But our Client achieved the THD around  less than 1% at  300W with 2 x tas5630 at Load of 33.3ohms

    Kindly please suggest counter Measure for this Issue

    Regards

    R.Rajesh

  • 0 in reply to Rajesh Ramesh
    Prodigy 130 points

    Dear Dan

    I have use start Capacitor of 0.1uf instead of o.047uf may it cause increase in THD

    Regards

    R.Rajesh

  • 0 in reply to Dan Kisling
    Prodigy 130 points

    Dear Dan

    We coupling the 2 x tpa3255 using Transformer & loading with 33.3ohms Resistor

    But our Client achieved the THD around  less than 1% at  300W with 2 x tas5630 at Load of 33.3ohms

    Kindly please suggest counter Measure for this Issue

    PS:I have use start Capacitor of 0.1uf instead of o.047uf may it cause increase in THD

    Regards

    R.Rajesh

  • 0 in reply to Dan Kisling
    Prodigy 130 points
    Dear Dan

    We coupling the 2 x tpa3255 using Transformer & loading with 33.3ohms Resistor

    But our Client achieved the THD around less than 1% at 300W with 2 x tas5630 at Load of 33.3ohms

    Kindly please suggest counter Measure for this Issue

    PS:I have use start Capacitor of 0.1uf instead of o.047uf may it cause increase in THD

    Regards

    R.Rajesh
  • 0 in reply to Rajesh Ramesh
    TI__Expert 6195 points
    Hi R. Rajesh,

    Sorry for the delay in response.
    Could you answer the following questions:

    1. What is the PVDD supply voltage?
    2. Are both Master and Slave device reaching this 300W at 2.8% THD?
    3. What is the turns ratio of the transformer?
    4. Where are you measuring the output? Before the LC filter? Before the transformer? After the transformer?
    5. If you are able, can you attach a power vs. THD sweep for your setup?

    Thank you,
    Dan