LINEAR TECHNOLOGY LTC6801 high voltage battery stack fault monitor operates without a microprocessor and without the need for optocouplers or isolators. Device can monitor up to 12 series-connected battery cells for overvoltage and undervoltage conditions. Multiple units can be daisy chained, providing a method to monitor each individual cell in very long battery strings. When connected in a daisy-chain, a single differential clock output confirms that all cells in the stack are within the defined operating range. Clock interface provides high noise immunity and ensures that fault conditions are not hidden by frozen bits or short circuit conditions.