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ADC121C027: ADC121C027

Adrian Delforge
Prodigy 90 points
Part Number: ADC121C027

I am using the SOT package without alarm and an address line, ADR0. 

I am unable to receive anything other than 0xFF when reading register 0.

I suspect it is simply not converting and FF is the POR value.

The I2C transaction is by the book, ADDR is 0xA4, I receive the ACK, I write 0 for the register, send a restart with ADDR 0xA5, and read 2 bytes. This works well with a variety of other A2Ds.

I tested the ACK from the device by setting ADR0 low and it does not send the ACK.

I tried reading 4 bytes in succession all come back 0xFF.

I have tried ADR0 low and addressed 0xA2,0xA3 - same result - ack's but no data.

The input to VIN is 0V., VA is 3.3V, SDA and SCL are 3.3V level.

Any suggestions to resolve this would be greatly appreciated.

I2C transaction image below:

 

  • 0
    TI__Expert 7162 points

    Hi Adrian,

    Thank you for your question!

    For ADR0 tied to GND, the hardware address would be 0xA2. As shown in your attached image, 0xA2 is address byte (frame 1) you use when writing to point to the conversion register, 0x00 (frame 2). Why are you then reading from address 0xA3 in frame 3? I believe you should be reading from 0xA2, as that is the hardware address of the device, set by tying ADR0 pin to GND.

    I hope this helps!

    Best,

    Samiha