Post Go back to editing

SSM2518 hiss while sending zero signal

Category: Hardware
Product Number: SSM2518

We are using the SSM2518 in an MCU design - it is driven via I2S output from an LPC5506 MCU. We are using a wide variety of MCLK speeds and configurations to support many file sample rates, but most are 48kHz 16-bit short audio samples. Our code is set up to un-mute the amplifier, play the audio sample, and then re-mute the amplifier.

We observe a distinct and very audible hissing sound, both while audio is playing, and most importantly after the amplifier has been commanded to soft mute. 

The amplifier is configured with the right channel disabled - we only need mono output.

We also have volume link enabled, which feels like it could cause an issue. However, I have tried disabling it and have not noticed any problem. 

I have seen another identical question on this forum that had been marked as resolved, but did not offer a solution. Any ideas?

Thank you,


  • Hi Alex,

    I'd be happy to help troubleshoot this problem.

    Would you be able to provide me with a list of the register writes/status reads and the schematic of your setup? 

    From reading the details of you setup, it seems the SSM2518 could be caught in a cycle of Unlimited Automatic Recovery Attempts and Over Current/Temperature Recovery Fault conditions.

    If you were to change the Number of Auto Recovery Attempts to one of the 1/3/7 Attempts options, the amplifier should turn off after the selected Auto Recovery Time. Once it's turned off, try toggling the Manual Fault Recovery Attempt bits to see if the hiss sound persists. 

    If you have any other questions, please feel free to reach out. If you can provide me with the list of register writes and status reads along with the schematic of your setup, we should be able to figure out this issue rather quickly. Thanks!