LM73: Absolute Maximum Ratings of Interface pin

Hi Yamamoto-san,

The diode which you drew, titled "Equivalent Circuit," is wrong. This does not exist in LM73. Page 3 of the LM73 datasheet has illustrations for the CLK and DAT pins. Additionally, Page 4 explicitly states, in 6.1 Absolute Maximum Ratings, that CLK and DAT pins may go up to 6V regardless of Vdd. This is the correct way to build an SMBus/I2C compliant device. Not all devices are created this way. The bus is defined this way such that pull-up resistors create the logic high while devices can only pull down to create logic low. This has the added benefit that mixed logic levels can co-exist without the need for level shifters as you have suggested. I'm attaching an illustration below which shows how this system should be implemented.

Thanks,

Ren