About pull-up resistor value of ALERT、SCL、SDA of the TMP102

Jacky Chen29

Genius 4735 points

Hola,

According to the data sheet below：

I have some questions about these pull-up resistors value below：

1. Why EVM's pull-up resistors uses 10K ohms and 300 ohms for SDA、SCL and ALERT？

2. What's the suggestion value for Fast mode(1KHz to 400KHz)？

3. What's the suggestion value for High-Speed mode(3.4MHz)？

over 7 years ago

0 Aaron Heng over 7 years ago

TI__Mastermind 31650 points

Hi Jacky,

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

Aaron

0 Aaron Heng over 7 years ago in reply to Aaron Heng

TI__Mastermind 31650 points

Hi Jacky,

We normally recommended the typical value of 5kΩ, but a typical range for the pullup resistor is about 1kΩ to 10kΩ depending on your system bus capacitance. In order to obtain the pullup resistance of your system, we need to know what the bus capacitance is. For this reason, I think we have chosen the 10kΩ pullup resistor for this dongle interface.

The intention of the 300Ω on Alert pin is a current limiter resistor by protecting the LED from damage when supply directly.

Aaron

0 Jacky Chen29 over 7 years ago in reply to Aaron Heng

Genius 4735 points

Hola Aaron,

Can you provide me a formular which can calculate these resistance ?

Because I want to use it to calculate the suitable resistance for fast mode and high speed mode. Thank you ~

0 Jacky Chen29 over 7 years ago in reply to Jacky Chen29

Genius 4735 points

Hola,

Can someone help to answer my urgent issue？Thanks ～

0 Ren Schackmann over 7 years ago in reply to Jacky Chen29

TI__Mastermind 37275 points

Hi Jacky,

This question was answered in a duplicate thread. See e2e.ti.com/.../1917104

I'm marking this thread as answered for housekeeping for purposes.

Thanks,
Ren

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About pull-up resistor value of ALERT、SCL、SDA of the TMP102