TPA3116D2: When I use a load of 2ohm, THD+N and flatness of Frequency response become very bad.

user6567359

Part Number: TPA3116D2

I use one TPA3116 amps in my circuit. In my circuit I use a single supply +24V.

In order to get 100W output power, I use the MONO MODE (PBTL) .

When I use a load of 8ohm, the performance index is very good. The THD+N and flatness of Frequency response are all good, the flatness is ±0.1dB（40Hz~16KHz）.

But when I use a load of 2ohm, THD+N and flatness of Frequency response become very bad. The flatness becomes ±2dB（40Hz~16KHz）.

The schematic diagram is just as the reference design in Datasheet.

How can I fix this problem ?

Looking forward to your reply，thank you！

over 4 years ago

0 Yanming Gong over 4 years ago

TI__Mastermind 19840 points

Hi,

Compared 2ohm and 8ohm load, the output current is higher on 2ohm than 8ohm load on same output power.

With the current increasing, the inductor(L1 and L2) nonlinearity will be more serious. So the 2ohm load performance is worse than 8ohm load on same output power condition. You can refer the curve of Inductance vs. DC Current in inductor datasheet.

Regards,

Derek

0 user6567359 over 4 years ago in reply to Yanming Gong

Prodigy 50 points

Hi，

In this case, do I need to replace the inductor with the same value? Or change different Inductance value?

Looking forward to your reply，thank you！

0 Yanming Gong over 4 years ago in reply to user6567359

TI__Mastermind 19840 points

Hi,

You can change higher Isat inductor to check again.

Regards,

Derek

0 user6567359 over 4 years ago in reply to Yanming Gong

Prodigy 50 points

Hi,

I changed a higher Isat inductor （4.7uH，11A），and the flatness became better. But there is another problem.

When the output power is high (for example, 100W), THD+N can not be stable and is slowly getting worse.

How can I fix this problem ?

Looking forward to your reply，thank you！

0 Dylan Yao over 4 years ago in reply to user6567359

TI__Genius 10840 points

As there is another post already, i would close this thread.

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TPA3116D2: When I use a load of 2ohm, THD+N and flatness of Frequency response become very bad.