This paper describes a chip which implements 30 tri-state 350-V display drivers in a high-voltage MOS (HVMOS) technology using a dielectrically isolated substrate. Low-voltage contol logic is implemented on the same die, for data handling and input-output facilities. The device has been developed as a custom designed chip for Tape Automated Bonding (TAB) on a large glass substrate and is an important building block in the realization of low-power flat panel displays.