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TMP119: No acknowledge from second TMP119 connected over jumper on same I2C line but addressed at 0x49

Alisha Menon
Prodigy 10 points
Part Number: TMP119

Tool/software:

I have 1 PCB with a TMP119 on-board with the ADD0 pin tied to ground.

I am able to write to (and read from) this sensor over the I2C interface by addressing 0x48 with the SCL and SDA on the oscilloscope looking like for a write:

However, I have a second PCB that I am connected with jumper cables for SCL, SDA, 3.3V and GND to the first PCB. The second PCB also has a TMP119 with the ADD0 tied to 3.3V (V+).

Unfortunately, when I try to address it at 0x49, it is unable to write to the configuration register because the sensor never acknowledges after receiving the address.

The same thing happens for a read as well

I'm not sure why there would be an issue with the external temp sensor but not the on-board sensor, the only thing I changed is that it's connected over jumper wires and the ADD0 pin - would appreciate any assistance!

I tried addressing the external one at 0x4A and 0x4B but no change

  • 0
    TI__Mastermind 43215 points

    Hi Alisha,

    How many of these boards have you assembled? I suspect you have a solder assembly issue, and the problem may be exaggerated by your PCB layout. The on-board layout follows guidelines for BGA pads, but the off-board layout does not. There should not be more than one trace connected to each pad, and the trace width should not be more than 2/3 the diameter of the pad. Your layout can cause the IC to tilt, becoming non-planar with the PCB, during solder reflow.

    www.ti.com/.../snva009a

    thanks,

    ren