TMP422: Addressing second TMP422 when diode is between ESD diodes

Ken Lick

Prodigy 20 points

Part Number: TMP422
Other Parts Discussed in Thread: DXP

Using 2 TMP422's I am able to read back correct temperature measurements from the first device (TMP1) but the

2nd TMP422 (TMP2) read back is all high's (255). We're wondering if this is a result of the ESD Diode configuration

surrounding the Thermal Diode? Are the ESD diodes disrupting the addressing scheme for the 2nd device? Any

suggestions on what might be going on here are appreciated.

TMP422's powered to 5V

over 6 years ago

0 David Vaseliou over 6 years ago

TI__Expert 6820 points

Hi Ken,

Your images did not upload correctly. Can you please attached them to post.

Thanks,
David

0 Ken Lick over 6 years ago in reply to David Vaseliou

Prodigy 20 points

The TMP422's are powered to 5v

0 David Vaseliou over 6 years ago in reply to Ken Lick

TI__Expert 6820 points

Hi Ken,

When the device is checking for orientation of diode, it is most likely configuring incorrectly due to the other ESD diodes. The "Two-Wire Interface Slave Device Addresses" section in the datasheet on page 19 explains the procedure on how it chooses the orientation. This is most likely causes the I2C addressing issue and will also orientate the DXP and DXN pins not as you expect.

Thanks,

Sensors

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TMP422: Addressing second TMP422 when diode is between ESD diodes