Quiet fan speed control

A novel a circuit for driving a fan includes an output terminal for supplying the fan with drive power, a pulse width modulation driver, and a limiter. A first power terminal of the fan is held at a first voltage (e.g., 0V), and a second power terminal of the fan is coupled to the output terminal of...

Full description

Saved in:
Bibliographic Details
Main Author DHUEY MICHAEL J
Format Patent
LanguageEnglish
Published 02.08.2005
Edition7
Subjects
CALCULATING
CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS
COMPUTING
COUNTING
ELECTRIC DIGITAL DATA PROCESSING
ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
ELECTRICITY
MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
PHYSICS
PRINTED CIRCUITS
Online AccessGet full text

Cover

More Information
Summary:A novel a circuit for driving a fan includes an output terminal for supplying the fan with drive power, a pulse width modulation driver, and a limiter. A first power terminal of the fan is held at a first voltage (e.g., 0V), and a second power terminal of the fan is coupled to the output terminal of the driver circuit. The PWM driver provides a series of fan drive pulses on the output terminal, and the limiter prevents the voltage on the output terminal from falling below a predetermined voltage. The predetermined voltage is greater than the first voltage at which the fan's first power terminal is held, and is sufficient to keep the fan in motion even when the duty cycle of the PWM signal is 0%. In a particular embodiment the limiter includes a voltage clamp. In a more particular embodiment, the voltage clamp is a diode. In another particular embodiment, the limiter includes a switch for combining a PWM signal with a DC voltage at an output.
Bibliography:Application Number: US20020214414