Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Patent
1997-09-17
2000-02-01
Callahan, Timothy P.
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
With specific source of supply or bias voltage
327536, 327142, 327198, 36518911, 331 46, 331 48, 331 57, 363 60, G05F 110, H03K 302
Patent
active
060207817
ABSTRACT:
A step-up circuit includes a selection control circuit 50 for activating a start/stop signal STP by detecting an external power-supply voltage Vcc, which is stable at 3.3 V, to reach 2.0 V or more, a ring oscillator circuit 30 for generating and outputting a clock of a high frequency Fs when the start/stop signal STP is inactive, a ring oscillator circuit 10 for generating a clock of a low frequency fo, a selection circuit 40 for selecting the output of the oscillator 30 when the start/stop signal STP is inactive and for selecting the output of the oscillator 10 when the start/stop signal is active, and a charging pump circuit 20 driven by the clocks. High frequency Fs is initially used to quickly bring an output voltage up to a desired operating level and low frequency fo is used, in order to conserve power, to maintain the operating level once a predetermined level of the external power supply voltage Vcc has been reached in order to conserve power.
REFERENCES:
patent: 5075572 (1991-12-01), Poteet et al.
patent: 5159543 (1992-10-01), Yamawaki
patent: 5208557 (1993-05-01), Kersh, III
patent: 5416446 (1995-05-01), Holler, Jr. et al.
patent: 5418499 (1995-05-01), Nakao
patent: 5594391 (1997-01-01), Yoshizawa
patent: 5633825 (1997-05-01), Sakuta et al.
patent: 5694308 (1997-12-01), Cave
patent: 5801987 (1998-09-01), Dinh
Callahan Timothy P.
Englund Terry L.
Fujitsu Limited
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