Hardware/firmware co-design in an 8-bits microcontroller to solve the system-level ESD issue on keyboard

A hardware/firmware co-design solution in an 8-bit microcontroller has been proposed to practically fix the system-level ESD (electrostatic discharge) issue on keyboard products. By including special ESD sensors and an additional ESD flag into the chip, the fast electrical transient due to the system-level ESD zapping on the keyboard can be detected. The firmware stored in the ROM of the 8-bit microcontroller is designed to automatically check the ESD flag to monitor abnormal conditions in system operations. If the keyboard is upset or locked up by a system-level ESD transient, the microcontroller can be quickly recovered to a known and stable state. The 8-bit microcontroller with the hardware/firmware co-design solution has been fabricated in a 0.45 /spl mu/m CMOS process. The system-level ESD susceptibility of the keyboard with this 8-bit microcontroller has been improved from the original 2 kV (4 kV) to greater than 8 kV (15 kV) for contact-discharge (air-discharge) ESD zapping.