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TPA3128D2: Supply Current Confusion

Michael Feighan
Prodigy 20 points

Part Number: TPA3128D2

Hello all,

I'm going to use the TPA3128D2 as the power amp for my speaker. The datasheet states (page 7) that there is a 7.5 A over-current trip point. However the evaluation module TPA3128D2EVM user's guide (page 3) lists a current requirement of 8 A from PVCC to power up the board. How does it take 8 A to use the board?

Is this number describing continuous discharge to power the board at all or is this the current expected at full power or heavy bass? Or is it something else entirely?

 

On a side note, I'd appreciate if someone with more experience could estimate my current draw and power output.

Characteristics of my design:

 PVCC: 16.8 – 12 Vdc. 

Load Impedance: 4 ohm. 

Gain: 20 dB.

Max Power Out: ~25 W (estimated from Figure 38 of the datasheet on page 25)

 

Regards,

Michael.

  • 0
    TI__Mastermind 23260 points

    Hi Michael,

    Are you referring to the spec below in the EVM user guide? This is just stating you should use a power supply capable of 8 A if you want to evaluate the full capabilities of the amplifier. The amp will not always consume that much current. 7.5 A is the max that the amplifier can output, so if you consider efficiency of the amplifier it will draw a bit more current than that.

    For the power you can do (PVDD/sqrt(2))^2/Rl. This gets you the RMS output power. With 12 volts you will not reach the 25 W spec, but at 16.8 you will. 

    Regards,
    Sydney Northcutt