TMP112, TMP108 - I2C address pin setting

Ryuji

Guru 20090 points

Other Parts Discussed in Thread: TMP108

Hello,

If we connect the A0/ADD0 pin of TMP108/112 to the SCL pin, are there any problem ?
For example, is the following power sequence no problem?
1. Power ON the I2C pull up supply
2. Then Power On the temp sensor power supply.

Since the TMP108 A0 pin absolute maximum rating is (V+)+0.3V, the "V+" is powered on before I2C pull up power.
Are there other problem in this case?

Best Regards,
Ryuji Asaka

over 9 years ago

0 Aaron Heng over 9 years ago

TI__Mastermind 36880 points

Hi Asaka-san,

I'll look into this, and get back to you soon.

Aaron

0 Michael Wong over 9 years ago

TI__Expert 7220 points

Hi Ryuji,

We only see a problem if the VDD pin is connected to ground and power is applied to the SCL pin. There is high current draw (~4mA) into the SCL pin in this configuration due to an internal diode connected from the A0 pin (shorted to SCL) to the VDD pin. This also happens when A0 is shorted to SDA and powered is applied to the SDA pin. This problem does not exist if the VDD pin is open circuit or connected to a high impedance connection.

There should be no problem on the second case.

-Michael Wong

0 Ryuji over 9 years ago in reply to Michael Wong

Guru 20090 points

Hi Michael,

Thank you for the reply.
I have a other question.
Are there any pull up or pull down on the ADD0 pin?

Best Regards,
Ryuji Asaka

0 Michael Wong over 9 years ago in reply to Ryuji

TI__Expert 7220 points

Hi Ryuji,

This issue does not exist when the A0 pin is pulled up or down.

-Michael Wong

Sensors

Sensors forum

TMP112, TMP108 - I2C address pin setting