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TPA3116D2: Question about BD modulation and 1SPW modulation

Part Number: TPA3116D2

Dear TI experts,

My customer considers TPA3116D2 for their new project, and they have a question about BD/1SPW modulation.

BD modulation is described as follows in the datasheet;

- This is a modulation scheme that allows operation without the classic LC reconstruction filter when the amp is driving an inductive load with short speaker wires.

1SPW modulation is described as follows in the datasheet;

- The 1SPW mode alters the normal modulation scheme in order to achieve higher efficiency with a slight penalty in THD degradation and more attention required in the output filter selection.

And here are the questions;

1. Typical applications(fig 37, page 26) in the datasheet says that MODESEL pin is connected to GND. It means that BD modulation is applied, but classic LC filters are also designed in Typical applications.

Could you explain why?

2. Could you provide reference schematics for BD modulation and 1SPW modulation? (I can refer the LC filter schematic.)

3. what is the difference between BD modulation and 1SPW modulation in the developer's view and customer's view? (efficiency, performance, power consumption, etc?)

Best regards,


  • Hi Chase

     The external LC filter is no difference, when you use BD or 1SPW mode, please always follow datasheet's schematic. This two modes' difference is inside of the device. BD will use 50% duty cycle as idle, but 1SPW will use around 20%.

     For developer, 1SPW use very small idle duty cycle. So when output large power, one side of the OUT will easily becomes 0 voltage, only rely on another OUT pin to output audio, which is very similar with single end output. But for BD, both OUT will always output audio together (when no clipping happens), the real output will always be differential.

     For customer, 1SPW has smaller idle loss (low duty cycle), high efficiency (one side 0 voltage, only another side has PWM), but slight lower performance like THD (single end output performance will a little worse than differential).

  • Dear Shadow,

    Thank you for your support.

    I will discuss it with my customer, and post another thread if I have a question.

    Best regards,