TMP275: TMP275 I2C spec

Hayashi

Expert 1840 points

Part Number: TMP275
Other Parts Discussed in Thread: TMP116, TMP112

Hi teams.

My customer wants to design the system by I2C(STANDARD MODE).

This device is not described about standard mode.

My customer confirm the 6.6 Timing Requirements in datasheet.

Their system is tHDDAT is 3.35us(max).

Can this device use by standard mode?

Best regards.

Hayashi

over 6 years ago

0 Jose Arteaga4 over 6 years ago

TI__Expert 5695 points

TI support team will contact you shortly.

0 Ren Schackmann over 6 years ago

TI__Mastermind 35915 points

TMP275 was designed to be compatible with I2C Standard, Fast and High Speed modes. In recent years, it was discovered that some TMP products, such as TMP275, have issues with I2C Master that have aggressive HDDAT timing. As a product line, we went through our TMP catalog re-testing and re-specifying HDDAT on older products. The four nanosecond min value that you see in the TMP275 datasheet is a result of that testing. The I2C specification requires zero microsecond HDDAT. We feel that this high-resolution measurement of HDDAT paints a more accurate picture of actual device performance than claiming compatibility with an ambiguous spec.

Ren

0 Hayashi over 6 years ago in reply to Ren Schackmann

Expert 1840 points

I understood, it had been a issue the minimum timing at HDDAT.
And, you described it was designed to be compatible with I2C standard mode.
I just want to know if it is compatible to HDDAT(max).
And, would you recommend this device?

Hayashi

0 Ren Schackmann over 6 years ago in reply to Hayashi

TI__Mastermind 35915 points

You haven't supplied enough information to confirm compatibility. We need to know that the I2C Master will never produce a HDDAT less than 4ns. The max HDDAT of the master isn't of use in this case.

The TMP275 is a great product and I recommend it. If you are interested in other high-accuracy temperature sensors, have a look at TMP112 and TMP116. The latter was released this year and features a 0ns HDDAT.

Ren

0 Hayashi over 6 years ago in reply to Ren Schackmann

Expert 1840 points

Thank you for your answer.
I just wanted to know if could we use tHDDAT3.35ns (max) with I2C standard mode.
Let me know if it's not recommended.

regards,
Hayashi

0 Ren Schackmann over 6 years ago in reply to Hayashi

TI__Mastermind 35915 points

Previously you said 3.35us max, which is irrelevant to this discussion and poses no issue. We are looking for the min value.

An HDDAT of 3.35ns max would not be compatible, because it indicates that HDDAT will always be below TMP275 min.

Ren

0 Hayashi over 6 years ago in reply to Ren Schackmann

Expert 1840 points

I was to send you typo. Correctly, it is 3.35us(max) in max timing.
My customer is not mention to min timing in this case,as probably they are use in more than 4ns.

Regards,
Hayashi

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TMP275: TMP275 I2C spec