TMP300 problem

Johanne Chen

Prodigy 110 points

Other Parts Discussed in Thread: TMP300

I want to use TMP300 to detect the temperature around 0 ℃.

However, I try the schematic as attached file and pin3 output is always high.

Could you please help me to check the circuit?

Any advice is help.

many thanks in advance.

BRs

Johanne

over 14 years ago

0 Ian Williams over 14 years ago

TI__Mastermind 27715 points

Hello Johanne,

First I'd like to clarify what the intended functionality of your circuit is. You would like the TMP300 /OUT (pin 3) to stay high when T_A < 0C, then switch low when T_A > or = 0C. Is that correct?

I have a couple of recommendations regarding the schematic you provided. First, the V+ pin of the TMP300 should have a bypass capacitor to GND (same as the V_TEMP and T_SET pins). Also, using a value of 180k for R3 (R_SET) creates a trip point of 5C, not 0C. Per Equation 2 on page 6 of the TMP300 data sheet, a value of 167k is needed for a 0C trip point. You can use 165k or 169k, as those are more common values.

Best regards,

Ian Williams
Linear Applications Engineer
High Performance Linear

0 Ian Williams over 14 years ago in reply to Ian Williams

TI__Mastermind 27715 points

Hello again Johanne,

Do you have any feedback on my last post?

Regards,

Ian

0 Johanne Chen over 14 years ago in reply to Ian Williams

Prodigy 110 points

Hi Ian:

So far the test is good.

If we have problem, I will let you know.

Many thanks in advance.

Regards,

Johanne

0 Ian Williams over 14 years ago in reply to Johanne Chen

TI__Mastermind 27715 points

Johanne,

I'm glad to hear the tests are going well. Could you please comment on what resolved the issue for the benefit of the forum?

Best regards,

Ian

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TMP300 problem