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Supply turn-On time for TPA3131D2 in Mono Mode

Toyojiro Naokawa
Intellectual 1240 points
Other Parts Discussed in Thread: TPA3131D2, TPA3117D2

Hello Dear,

I am thinking to use TPA3131D2 as piezo driver in Mono mode. According to datasheet, the Mode will be detected in power up period. Is ther any suggestion about power up rising time? If the power up time is like 2ms to 10ms, the Mode detection will be correctly selected? Please advise this.

Best regards

T NAOKAWA

  • 0
    TI__Mastermind 37045 points

    Hi, Naokawa-san,

    Yes the mode detection will operate normally as long as the mode setting does not change during POR.

    reg,

    Paul Chen

    Audio Applications Engineer

    Dallas TX.

  • 0 in reply to user5276421
    TI__Intellectual 1240 points

    Hello Paul-san,

    Thank you for your quick response.

    Best regards

    T NAOKAWA

  • 0 in reply to Toyojiro Naokawa
    TI__Guru**** 189401 points

    Hi, Naokawa-san,

    If the capacitance of the piezo is too high, it may trip the over-current protection on the amp. You may need to adjust the filter, or add a series R to limit the peak current.

    -d2

  • 0 in reply to Don Dapkus
    TI__Intellectual 1240 points

    Hello Don-san,

    Thank you for your comment on Piezo load cap, filter and seriese R things. The load cap value is around 1.6uF one and other one is 3.2uF. And the required audio band width is 7K to 8khz @-3dB and output voltage swing on the piezo load is 27Vpp. To drive this load by Lion Baterry, we need a Boost conv with Vout=14.5V or 15V. Basic idea for driving the piezo load with Class-D amp needs one Inductor and small resistor. The inductor value is around 5uH for 3.2uF load and 10uH for 1.6uF load and series resistor is around 0.3 to 0.5 Ohm to reduce the Load Q. And also I put 2nd order LPF(arround 7khz) on the input then the peak current on the load which is flow In/out to amp outputs is around 1.5Amps or so. Even large current flow on the amp outputs, this current doesn't generate heat up and only thermal will generate on Rdson and seriese R which are very small power and The inductor will work energy return effect to power supply which is Booster. As the result Bat current doen't increase so much over the freq. Only concern is Pkg size is large and Iq of TPA3131 is large.  I found TPA3117D2 has smaller Iq compare with TPA3131D2. If you can send me a EVM of TPA3117D2, it will be very helpfull for my check.

    Best regards

    T NAOKAWA

  • 0 in reply to Toyojiro Naokawa
    TI__Guru**** 189401 points

    Hi, Naokawa-san,

    Doesn't TPA3117D2 have higher supply current than TPA3131D2?

    TPA3117D2 also has much higher rDS(on) than TPA3131D2.

    -d2

  • 0 in reply to Don Dapkus
    TI__Intellectual 1240 points

    Hello Don-san,

    Thank you for your attention on this. I think TPA3117D2 has smaller Iq compare with TPA3131D2. TPA3117  datasheet shows that  Icc @Vcc=12V is 15mA typ, and Vcc=26V is 25mA, TPA3131D2 datasheet shows Icc @Vcc=7.4V is 16mA and Vcc=19V is 27mA. My required supply voltage to get 27Vpp is around 14.5V to 15V. So from this required supply voltage, TPA3117 will have smaller Iq if Iq increament rate over supply voltage is proportional, TPA3117 will have smaller Iq. I think this expectation will be OK. How do you think?

    Best regards

    T NAOKAWA