Distance limitation for transmission of digital temperature data (TMP112/TMP422 etc)

Jayaram C B

Other Parts Discussed in Thread: TMP422, TMP112, P82B96, P82B715

Hi,

We are planning to use TMP112/TMP422 or any suitable temperature detector IC for measuring temperature of an electronics unit. This data needs to be transmitted to remote processor unit. Is there any distance limitation for this data transmission? Thanks in advance for the response.

over 13 years ago

0 Chris Featherstone over 13 years ago

TI__Mastermind 26065 points

Jayaram,

I am currently looking into this and will get back to you shortly.

0 Chris Featherstone over 13 years ago

TI__Mastermind 26065 points

Jayaram,

How long of a distance is the remote processor unit sitting from the sensor? Will the bus lines be PCB traces or ribbon cable...? The NXP I2C specification provides some help if the bus lines are greater than 10 cm. Specifically see page 60 in the specification link below:

http://www.nxp.com/documents/user_manual/UM10204.pdf

0 Jayaram C B over 13 years ago in reply to Chris Featherstone

Intellectual 370 points

Chris,

Thanks for your reply. Distance between the sensor and remote processor would be of the order of few hundred metres. Please suggest an appropriate measurement method if the one proposed by me wont suffice.

Thanks

Jayaram

0 Chris Featherstone over 13 years ago in reply to Jayaram C B

TI__Mastermind 26065 points

Jayaram,

I2C communication does not work well over 1 meter. The effects of line capacitance greatly impact the communication over this distance.

My recommendation is to communicate with the temperature sensor locally with an MCU. Use the controller to translate the data into a communication protocol such as RS45 to a transceiver. This communication method can be used over a long distance as in your application.

0 Jayaram C B over 13 years ago in reply to Chris Featherstone

Intellectual 370 points

Chris,

Thanks for your reply....Can you suggest an MCU & transceiver for this application?

Regards

Jayaram C B

0 DHarmon over 13 years ago in reply to Chris Featherstone

TI__Genius 16490 points

Jayaram,

There are I2C bus buffers that can be used to expand the bus up to 10s of meters - see P82B715 or the P82B96 as examples of devices that can accomplish this.

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Distance limitation for transmission of digital temperature data (TMP112/TMP422 etc)