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 S-bits microcontroller has bee n proposed to practically fix the system-level electrostatic discharge (ESD ) issue on the keyboard products. By including the especial 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-bits microcontroller is designed to automatical ly check the ESD flag to monitor the abnormal conditions in system operatio ns. 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. T he 8-bits microcontroller with such a hardware/firmware co-design solution has been fabricated in a 0.45-mum CMOS process. The system-level ESD suscep tibility of the keyboard with this 8-bits microcontroller has been improved from the original +/-2 kV (+/-4 kV) to become greater than +/-8 kV (+/- 15 kV) in the contact-discharge (air-discharge) ESD zapping. (C) 2001 Elsevie r Science Ltd. All rights reserved.