US Patent 8010724 12C/SMBus ladders and ladder enabled ICs

I2C/SMBus ladders and ladder enabled ICs (devices) to enable daisy-chained I2C/SMBus communication. The devices are particularly useful in monitoring and/or servicing high-voltage battery stacks and other voltage stacks. The devices are powered from a respective voltage increment in the voltage stack, and include level shifting circuitry so as to be operative with an input voltage up to the breakdown voltage of the level shifting circuitry. Various features are disclosed, including but not limited to a unique data line drive, capacitive coupling between devices in a daisy chain with line clamps for circuitry protection and capacitive coupling charge wiping, and clock stretching to accommodate chain latency.