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LM49352: respond to multiple i2c addresses

Lixun Lin
Prodigy 30 points
Part Number: LM49352


Hi there,

We have a custom board with LM49352 chip. We found that the chip respond to not only 0x1a, which is specified in the data sheet, but also a few other addresses.(0x68, 0x69, 0x6a, 0x6b)

To be more specific, for example, when I issue a READ function @ 0x68. The chip acknowledges this address.

We do have other i2c devices on the board. However, when I physically cut the power of the LM49352 chip. There is no acknowledgment any more. Therefore we conclude the ACK comes from LM49352.

We found the chip also reponds at 0x69, 0x6a and 0x6b. Is this a known issue or we miss anything?

Thank you very much.

  • 0
    TI__Guru 57800 points

    Hi, Lixun,

    Welcome to E2E, Thanks for your interest in our products!.

    This issue seems weird, the device should not ack to different I²C addresses, I have asked my colleague in charge of this device's support to take a look to this. As he is on holiday, the response might be delayed, sorry for the delay. 

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0
    TI__Guru** 110495 points
    Hi Lixun,

    Actually the datasheet specifies 0x34 as I2C address as the last bit is 0 for write and 1 for read. In addition the capture shows 0xD0 address with read bit, and I think the other addresses are 0xD2, 0xD4 and 0xD6 followed by the read/write bit.
    However the device should not respond to different I2C adresses. Have you tried with different ICs?
    I'll try to get more information of this issue although there is no EVM board available for testing.

    Best regards,
    -Ivan Salazar
    Texas Instruments
  • 0 in reply to Ivan Salazar
    Prodigy 30 points

    Hi Ivan,

    Thanks for your reply!

    I think we are talking about the same thing but with different interpretation. The address specified in datasheet is (0011010) in binary, which is 0x1a in 7-bit address and 0x34 when includes in the last bit(R/W).

    We confirm that it does ack on other addresses such as 0xD2, 0xD4, 0xD6 in 8-bit address. We have also tried different clock speeds such as 100kHz and 400kHz. They both behave the same.

    Best Regards,

    Lixun

  • 0 in reply to Lixun Lin
    TI__Guru** 110495 points
    Hi Lixun,

    What I found is that LM49352 sends ACK (is visible) on I2C addresses 0x1A, 0x34, 0x35, 0x68, 0x69, 0x6a and 0x6b. but if you actually try to write some data to addresses other than 0x1A, the device will always NACK on the first data byte.
    The addresses I’ve listed are 7-bit, so 0x1A is 0x34 for 8-bit write.

    Best regards,
    -Ivan Salazar
    Texas Instruments
  • 0 in reply to Ivan Salazar
    Prodigy 30 points

    Hi Ivan,

    Thanks for the reply and findings.

    So can I assume this is a chip problem? Will you fix it in the future?

    Best Regards,

    Lixun

  • 0 in reply to Lixun Lin
    TI__Guru** 110495 points
    Hi Lixun,

    Yes this seems to be an issue with the chip.
    I'm not sure if this will be fixed as these LM devices do not usually get revision changes in the device, only the documentation.

    Best regards,
    -Ivan Salazar
    Texas Instruments