TMUX121: Charge pump

Hey Hailiang,

There aren't any pullup resistors internally on this device but I don't believe we can share the structure of the charge pump itself. 
What is their interest in the charge pump with regards to the I2C bus? The I2C bus should be on the Dx to SxA/B paths but the charge pump will just bias the gates that will turn on the FET path from D -> S so it won't be adding any pullup impedance for their calculations.

I'll still run it by my design team though to see if there's anything I may be overlooking.

Thanks,
Rami

Hi Team,

The schematic looks fine from my side. One concern is the 1k resistor at EN# pin. Could you pls help also review the schematic below and suggest?

Regards,
Hailiang

Hey Hailiang, 

Is there a reason they're using the TMUX121 for I2C? We can probably offer a cheaper solution for something as simple as I2C. TS5A23157 is a good option.

But on the schematic itself I don't see any issues. The pull down on EN is fine. If they're just planning on holding it low always and always have the mux active they can even just lose the resistor and tie to ground directly.

Thanks,
Rami

Hi Rami,

Thanks for your comments.

Do you have any updates for this?

I'll still run it by my design team though to see if there's anything I may be overlooking.

Regards,
Hailiang