The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 27, 1995
Filed:
Jan. 03, 1992
Andre B Walker, Los Gatos, CA (US);
Victor So, San Jose, CA (US);
Zilog, Inc., Campbell, CA (US);
Abstract
A microcontroller power management system wherein the voltage of a power supply is monitored and the microcontroller central processing unit ('CPU') receives an interrupt signal when the supply voltage falls below a predetermined level. The CPU monitors the duration of the low voltage condition and switches into a sleep mode, after storing any data in its registers that are not maintained in the sleep mode, when that duration exceeds a fixed limit that indicates more than a temporary power glitch is being experienced. If only a short power glitch, the CPU continues normal operation. A large capacitor connected to the power supply input to the microcontroller provides enough energy for the microcontroller to operate normally during short glitches and to operate in a sleep mode for a considerable time, thereby maintaining data in CMOS static RAM until power is restored. This is particularly useful for battery operated systems, responding to both a low battery voltage condition and to a complete loss of power during battery replacement.