Voltage boosting circuits having backup voltage boosting capability

Abstract

Voltage boosting circuits include backup voltage boosting circuits which are enabled during high current loading conditions when voltage sags in the potential of a boosted signal line(s) are encountered, and which provide independent level detection capability to bypass main voltage level detectors when relatively severe voltage sags are anticipated. In particular, voltage boosting circuits are provided which contain a main voltage boosting circuit and a backup voltage boosting circuit therein. The main voltage boosting circuit is typically powered at a first reference potential (e.g., Vcc) and preferably contains a main level detector, a built-in oscillator and a main pump coupled in series to drive a signal line (e.g., Vpp) to a boosted reference potential which is greater than the first reference potential, if a potential of the signal line drops below a second reference potential. To supplement the voltage boosting capability of the main pump, a backup voltage boosting circuit is provided containing an independent voltage level detector and at least one backup pump coupled in series therewith, to drive the signal line to the boosted reference potential, if the potential of the signal line drops below a third reference potential which may be greater than or equal to the second reference potential. Accordingly, the occurrence of relatively small voltage sags in the potential of the boosted signal line (e.g., Vpp) can trigger the backup pump during anticipated high current loading conditions, while the occurrence of larger voltage sags in the potential can trigger the main pump to assist the backup pump.