TMP235: measure temperature difference between two points

Howard Zou

Part Number: TMP235
Other Parts Discussed in Thread: TMP112, LMT70, TMP431, TMP116

Hi,

my customer would like to measure the temperature difference between two points of a sink.

Since TMP235 maximum error is ±1.2C, if they use two TMP235, the temperature difference error will be 2.4C max, which is too large.

Maximum error within 1C is good.

Do you have good proposal?

over 4 years ago

0 Brandon Fisher94 over 4 years ago

TI__Mastermind 28070 points

Hi Howard,

It sounds like you need a sensor that is at least +/- 0.5 °C accurate. What is the temperature range of interest?

The TMP112 (+/- 0.5 °C from 0 °C to 65 °C) is a good option if you are okay using a digital part. There are other digital options listed here that also meet the 0.5 °C accuracy requirement over different ranges.

For an analog sensor, the LMT70 would be our highest accuracy analog part, and any two would easily meet +/- 1 from -55 °C to 150 °C.

Best Regards,
Brandon Fisher

0 Howard Zou over 4 years ago in reply to Brandon Fisher94

TI__Genius 12365 points

LMT70 is good but expensive.

I'm wondering if TMP431 is a good choice. It has 2 remote sensor, each is within ±1C. If these 2 sensor's error are in the same direction(for example, both are positive error or both are negative error), the temperature difference will be within 1C. But I'm not sure if the error would be in the same direction for 2 remote channel.

0 Brandon Fisher94 over 4 years ago in reply to Howard Zou

TI__Mastermind 28070 points

Hi Howard,

TMP431's remote sensor channels unfortunately aren't guaranteed to have the same offset. They also require a thermal diode at each sensing point, and depending on manufacturer there can be variations in N-factor for such diodes that contribute to differences in channel readings.

The TMP112 may still be the best option if they are okay with the 0 °C to 65 °C temperature range. If not, the TMP116 could support their accuracy requirement over a larger range (-40 °C to 125 °C), but it will be more expensive than the TMP112 and TMP235.

Best Regards,
Brandon Fisher

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TMP235: measure temperature difference between two points