LM48100Q-Q1: Issue with audio outputs not inverting

Hi Matt,

Could you please comment on a couple of things?:

• Does this behavior happen every time you power up the device? Or is it changing after every power cycle?
  • Read the device registers before and after the issue happens, is there any difference?
  • Try by writing Mode and Volume registers again, even if you write the same value as it was originally. Does the device go back to normal operation?
• Are you testing more than 1 device? How many devices show this behavior?

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan,

Thanks for your quick response.

• Yes this behaviour occurs every time I power up the device.
• There is no before and after the issue, as it is from power_on indefinitely.
  • My understanding was the LM48100Q-Q1 is a WRITE-ONLY device and will not respond to a R/W = 1?
• I write the registers as follows:

  • Register Address	Register Name	B7	B6	B5	B4	B3	B2	B1	B0
    0	MODE CONTROL	0	0	0	1	0	1	0	0
    1	DIAGNOSTIC CONTROL	0	0	1	1	0	0	0	0
    2	FAULT DETECTION CONTROL	0	1	0	0	0	0	0	0
    3	VOLUME CONTROL 1	0	1	1	1	1	0	1	1
    4	VOLUME CONTROL 2	1	0	0	0	0	0	0	0

• Unfortunately I only have one device to test at the moment.

Many thanks,

Matt

Hi Matt,

Can you try with the following procedure:

• write Volume Control 1 = 0x7B

• Mode Control Register = 0x00

• Mode Control Register = 0x14

The only mention of similar type of issue is from this previous post: [ LM48100-Q1 ] Malfunctioning Output - Audio forum - Audio - TI E2E support forums
Which seem to be caused after an ESD event.

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan,

I have written the registers in the procedure you described, but the same output behaviour occurs. The outputs are disabled by the "Mode Control Register = 0x00" and then enabled again by "Mode Control Register = 0x14". When enabled they are still identical waveforms out of OUT A and OUT B.

Thank you for the link. It appears they did not find a solution to their problem, but perhaps suggests that my problem may also be a result of a similar ESD event.

Is there a way to read the registers from the LM48100Q-Q1?

If there are no further solutions I could try I will have to go with another option or get a second device to try in case this one has indeed also suffered a death from an ESD event.

Kind regards,

Matt

Hi Matt,

I agree, unfortunately it would seem like a similar behavior after ESD event. Would be good to try with a new device to check if that's the case.

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan,

Thank you for your support. Ok I will give it a go with a new device when I can get hold of one.

Kind regards,

Matt