BQ78Z100 Spec 7.26 I2C and HDQ Interface I/O Parameter: Rpd=3.3K. Wondering about that, is there really a pull down resistor on Data or Clock port? Isn't that a typo?
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10K pullup between the BQ and the TXS should be fine.
As long as the BQ VinH VinL are met by the TXS0102 translator.
Also see this app note about I2C Speed vs Pullup vs bus capacitance.
How you plan on using the I2C determines how you terminate it.
Higher speed + high buss capacitance = lower value pullup needed to maintain the speed.
Thank you for the reply.
I understand the pull down resistor for chip sensing the bus line and going into sleep mode. We usually use a external 1M resistor for other chips, like bq20z65 etc. For bq78z100, if a 3.3K internal pull down resistor is always there, how can a bus line be pulled up to high level by a 2K resistor from 3.3V? The level of bus line may be only 3.3/(2+3.3)*3.3V=2.05V when it is pulled up?
Thank you for the reply Onyx! However, I don't understand "That 3.3K Rpd would be the pull down resistance when the device is actively pulling the I/O low". I don't think I2C can work under the condition where the pull down resistance of I/O would be 3.3K. It must be something I misunderstood.