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, 2006
Filed:
May. 11, 2004
Leonid A. Bekker, Holbrook, NY (US);
Uri Segal, Farmingdale, NY (US);
Leonid A. Bekker, Holbrook, NY (US);
Uri Segal, Farmingdale, NY (US);
Standard Microsystems Corporation, Hauppauge, NY (US);
Abstract
A system and method for generating a test signal used in measuring the speed of a rotating device, such as a fan in a computer system is disclosed. A pulse width modulated (PWM) signal may power the fan with the duty cycle of the PWM signal controlling the speed of the fan. The fan may generate tachometer pulses used for monitoring RPM of the fan. The frequency of the test signal may be selected to be at least twice the frequency of the tachometer pulses. The test signal may be generated from a base frequency signal using two cascaded frequency dividers. The first divider may output a scaled base frequency signal obtained by dividing the base frequency signal by a user programmable scale frequency coefficient corresponding to a maximum test signal frequency for the fan. The second divider may output the test signal by dividing the scaled base frequency signal by a fraction frequency coefficient obtained from and proportional to the current PWM duty cycle value. The test signal may be multiplexed with the PWM signal to obtain existing tachometer pulses even when the PWM signal is not asserted. The scale frequency coefficient may only need to be programmed once for each fan.