LM48511 output is abnormal

user4863737

Prodigy 35 points

Output RMS value is just 500mV. Target value is more than 4.4V.

Below is our schematic.

VBATT:4.2V, VDD_LM:7.8V

Input signal is single input.(CDC_HPH_REF is analog ground)

With the same input signal using AW8733(AMP) output RMS value is 4V.

Please tell me how can i debug LM48511 in this case.

over 8 years ago

0 José Luis over 8 years ago

TI__Mastermind 20085 points

Hello

Welcome to E2E, thanks for your interest in our products.
The schematic seems right. Which is the input level that you are using in the device?
You could take the measurements without the output filter in order to discard a problem in this filter.

Best Regards
Jose Luis Figueroa
Audio Applications Engineer

0 user4863737 over 8 years ago in reply to José Luis

Prodigy 35 points

Hi

Thanks for your reply.
>Input signal RMS value is 264mV.
>Measured chipset output directly(before L513 and L513) and output level is the same just 500mV.

0 user4863737 over 8 years ago in reply to José Luis

Prodigy 35 points

We also reduce R554 and R555 to 10k,5.1k,2.2k,2k and RMS value is increased to3.2V.

If reduce R554/R555 more that output signal will accur distorsion.

0 José Luis over 8 years ago in reply to user4863737

TI__Mastermind 20085 points

Hi

Regarding the measurement, you should disconnect the output filters and take the measurement.
When you reduce those resistors , you increase the device's gain if the output signal is increased until THD+N is higher than 10%, the device begins to get distortion.

Best Regards
Jose Luis Figueroa
Audio Applications Engineer

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LM48511 output is abnormal