Capacitive charge pump driver circuit for piezoelectric alarm
AssigneeTimex Corporation
InventorBruce H. Kamens
Life of this patent
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Abstract
A capacitive charge pump circuit and associated method is provided for outputting an output voltage which has a magnitude which is an integer multiple of the magnitude of a power supply voltage used to power the circuit. In one form, a capacitor is charged to the power supply voltage, V.sub.s. The capacitor is alternately coupled to the power supply voltage and ground so that in an alternating manner, 2 V.sub.s and -V.sub.s appear across it. By coupling a first electrode of a piezoelectric crystal to the capacitor and a second electrode of the piezoelectric crystal to the power supply voltage, a signal having a peak-to-peak magnitude which is three times that of the power supply voltage will drive the piezoelectric crystal.
Claims11
A capacitive charge pump circuit which provides to a piezoelectric crystal a voltage having a peak-to-peak magnitude which is at least substantially three times a first potential provided by a power supply source, comprising:
- a first switching means coupled to the power supply source, the power supply source having a power supply terminal and a ground reference terminal;
- a single capacitor coupled to the first switching means, the capacitor being charged to substantially the first potential by operation of a first control signal coupled to the first switching means;
- a second switching means coupled to the capacitor and the ground reference terminal, the second switching means translating the potential across the capacitor to a second potential;
- a third switching means coupled to the capacitor and the power supply terminal, the third switching means translating the potential across the capacitor to a third potential;
- the piezoelectric crystal having a first and a second electrode, the second electrode being coupled to a fourth potential;
- and
- means for alternately coupling the second switching means and the third switching means to the first electrode of the piezoelectric crystal so that the first electrode alternates between the second potential and the third potential.
A capacitive charge pump circuit which provides to a piezoelectric crystal a voltage having a peak-to-peak magnitude which is at least substantially three times a first potential provided by a power supply terminal, comprising:
- a first switch having a first terminal coupled to the power supply terminal, a second terminal, and a control terminal for receiving a first control signal;
- a single capacitor having a first electrode coupled to the second terminal of the first switch, and a second electrode;
- a second switch having a first terminal coupled to a ground reference terminal, a second terminal coupled to the second electrode of the capacitor, and a control terminal for receiving the first control signal;
- a third switch having a first terminal coupled to the first electrode of the capacitor, a second terminal coupled to the ground reference terminal, and a control terminal for receiving a second control signal;
- a fourth switch having a first terminal coupled to the second electrode of the capacitor, a second terminal, and a control terminal for receiving the second control signal;
- a fifth switch having a first terminal coupled to the first electrode of the capacitor, a second terminal, and a control terminal for receiving a third control signal;
- a sixth switch having a first terminal coupled to the second electrode of the capacitor, a second terminal coupled to the power supply terminal, and a control terminal for receiving the third control signal;
- the piezoelectric crystal having a first electrode and a second electrode, the first electrode being alternately coupled to the second terminal of the fourth switch and the second terminal of the fifth switch by operation of the second and third control signals so that a second and a third potential alternately appear at the first electrode of the piezoelectric crystal;
- and
- means, coupled to the second electrode of the piezoelectric crystal, for selecting between the first potential and a reference potential coupled to the ground reference terminal.
A capacitive charge pump circuit which provides to a piezoelectric crystal a voltage having a peak-to-peak magnitude which is at least substantially five times a first potential provided by a power supply terminal, comprising:
- a first switch having a first terminal coupled to the power supply terminal, a second terminal, and a control terminal for receiving a first control signal;
- a first capacitor having a first electrode coupled to the second terminal of the first switch, and a second electrode;
- a second switch having a first terminal coupled to a ground reference terminal, a second terminal coupled to the second electrode of the first capacitor, and a control terminal for receiving the first control signal;
- a third switch having a first terminal coupled to the power supply terminal, a second terminal, and a control terminal for receiving the first control signal;
- a second capacitor having a first electrode coupled to the second terminal of the third switch, and a second electrode;
- a fourth switch having a first terminal coupled to the ground reference terminal, a second terminal coupled to the second electrode of the second capacitor, and a control terminal for receiving the first control signal;
- a fifth switch having a first terminal coupled to the second electrode of the first capacitor, a second terminal coupled to the first electrode of the second capacitor, and a control terminal for receiving the first control signal;
- a sixth switch having a first terminal coupled to the first electrode of the first capacitor, a second terminal, and a control terminal for receiving a second control signal;
- a seventh switch having a first terminal coupled to the second electrode of the second capacitor, a second terminal coupled to the power supply terminal, and a control terminal for receiving the second control signal;
- an eighth switch having a first terminal coupled to the first electrode of the first capacitor, a second terminal coupled to the ground reference terminal, and a control terminal for receiving a third control signal;
- a ninth switch having a first terminal coupled to the second electrode of the second capacitor, a second terminal, and a control terminal for receiving the third control signal;
- the piezoelectric crystal having a first electrode and a second electrode, the first electrode being alternately coupled to the second terminal of the sixth switch and the second terminal of the ninth switch by operation of the second and third control signals so that a second and a third potential alternately appear at the first electrode of the piezoelectric crystal;
- and
- means, coupled to the second electrode of the piezoelectric crystal, for selecting between the first potential and a reference potential coupled to the ground reference terminal.
Dependencies are inferred from the claim text.