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TPA3138D2: TPA3138D2 - 1SPW mode - BTL output - loading and current limit question

Solong
Prodigy 40 points
Part Number: TPA3138D2

Tool/software:

We use TPA3138D2 for our AMP design , we find some protect issue need TI proivde detail information

Our Design Setting:

a)1SPW Mode 

b)Stereo BTL output 

c)PVDD 8V supply 

d)20dB Gain

e)PLIMIT Set to GVDD

f)4 Ohm DCR speaker loading (impedance on some frequency impedance low to 3.2 Ohm)

Question:

1.On the SPEC ,  BTL Model support 3.2 Ohm resistance , we want to know It is accept to driver 4 Ohm DC resistor (3.2 Ohm impedance at some frequency) speaker driver with +/- 20% and do not go into protect mode?

2.On the SPEC haven't OCP informaiton, We want to know 1SPW/BTL mode the over current information(Min/Max) @ IC 25C and 100C stage.

3.We are design the system sensitivity , and want to take more hearroom margin , When we use 30% clip's , below 5KHz sine wave(with 3R resistor load) amplifier work normal, when the frequency more than 5KHz, IC very easy to go into protect mode . Are the IC support high clip working mode ? if not , how many %'s clip is the up limit are your suggest (10%? 15%? 20%?) and confirm IC can work normal at 20Hz to 20KHz ? 

Normal design :  DAC 0dBFS output , we are sestting Amplifier output around 10% Clip THD (0.5dB margin)

More hear-room design:DAC -10dBFS output , Amplifier output around 10% clip THD

                                      DAC    0dBFS output , Amplifier output around 30% Clip THD

  • 0
    TI__Mastermind 20241 points

    hi, solong

    sorry for late reply.

    i need to check with team member, i will reply you within this week.

    thx

    jesse

  • 0 in reply to Jesse Ji
    Prodigy 40 points

    Thanks for your support

    Waitting for your update.

  • 0
    TI__Mastermind 20241 points

    hi, sorry for late reply.

    1.low resistor might trigger the oc easily. so below 3.2ohm might lead to amp go protection more easier during our validation. we used dummy load for the testing. 

    2.you can simply consider 10% margin for amp.

    3.high clipping mode mainly limited by the temperature and over current threshold.

    you can take a measure the voltage at 30% to see whether might lead to current close to OC threshold.

    also, you can use the thermal gun testing the temperature whether the thermal go high quickly when input over 5khz.

    thanks

    jesse

  • 0 in reply to Jesse Ji
    Prodigy 40 points

    1.In fact, the 2R load we use does not trigger OCP at room temperature, but it is possible to trigger OCP in an environment of 40 ℃. Therefore, we believe there is room for using TI's IC, but we are also concerned that this is a case and cannot represent the upper and lower limits of IC performance. Therefore, we would like to obtain confirmation from TI whether the IC supports 2.6R impedance and will not trigger protection at high temperatures (8V power supply)?

       On your test , how load loading can triggered overcurrent protection? How many current at that time?

    2.Thanks for your reply , I will set it as our design up limit.

    3.I am  test it as cool start and confirm the thermal is <70C , how many current your are setting for OCP? please share for us.

  • 0 in reply to Solong
    TI__Intellectual 2060 points

    Hi Solong,

    We have received your feedback, and will check internally and feedback to you.

    Br,

    Wenbin

  • 0 in reply to Wenbin Li1
    Prodigy 40 points

    Hi WenBin:

    Do you have any update ? 

  • 0 in reply to Solong
    TI__Intellectual 2060 points

    Hi Solong,

    we only have the test data based on the normal temperature. so the higher room temperature results should be based on the real test setup.

    and as you can get in the datasheet, the only tested THD data is 10%. so 10% THD is suggested and higher THD should be tested based on the real usecase.

    Br,

    Wenbin

  • 0 in reply to Wenbin Li1
    Prodigy 40 points

    Hi WenBin:

      There is no description of the ampere value for overcurrent protection in the datasheet on the TI website.

     Could you share for us today?

  • 0 in reply to Solong
    TI__Intellectual 2060 points

    Hi Solong,

    there is only typical max output current in datasheet. and didn't have the OC current. you can refer to the below figure.

    you can use this value as reference. 

    this chip is too old to get the design data for this value. sorry for that.

    Br,

    Wenbin