LM48511: Question of the LM48511SQ Output Power

Wayne Chen (Audio AE)

Part Number: LM48511

Hi Sirs,

The LM48511 datasheet specifies 5.4W 1% THD+N with 4ohm load, 6.7W 10% THD+N with 4ohm load.

However, we were not able to achieve 5W 1% THD+N on the EVM with 5V power supply. We tried to reduce PV1 voltage drop by changing a 10A Schottky Diodes, increasing R6, R8 to 39kR to the EVM (picture below), we got 5.002W, 5.67% THD+N, 4.383W, 0.96% THD+N with 4ohm load in the best case.

Would you pls advise the process to reproduce 5W, 4ohm, 1% THD+N on the EVM?

Thank you and Best regards,

Wayne Chen
09/04/2017

over 8 years ago

0 José Luis over 8 years ago

TI__Mastermind 20085 points

Hi Wayne,

I have a couple of questions.
What type of input is the device using (single-ended or differential)? and, Could you provide me additional information about the configuration? For instance, where FB_SEL and SS_EN enable pins are tied.

Best Regards
José Luis Figueroa
Applications Engineer

0 Wayne Chen (Audio AE) over 8 years ago in reply to José Luis

TI__Genius 15950 points

Hello Jose,

Thanks a lot. We pulled the FB_SEL to high, SS/FF# to low. We reduced the Vboost a little bit (R3=25.5kR->24kR) 7.8V with no load) to avoid LM48511 damage in light load.

Thanks a lot,

Wayne Chen
09/05/2017

0 José Luis over 8 years ago in reply to Wayne Chen (Audio AE)

TI__Mastermind 20085 points

Hi Wayne,

I was researching and It seems that the package is very tiny to handle this power. The dissipation would be very high and the IC would get too hot. I think the power of 5.4 W has been measured with a burst signal from the Audio Precision(AP).

Best Regards
José Luis Figueroa
Applications Engineer

Audio

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LM48511: Question of the LM48511SQ Output Power