National Semiconductor Corporation

Eric Tam

Chungwai Benedict Ng

Mehmet Aslan

Dan D'Aquino

Qing Feng Ren

Eugene Quan

A pulse width modulation (PWM) device, system and method for high resolution fan control are disclosed. In one embodiment, the method comprises determining a target duty cycle of a PWM signal, determining the number of PWM cycles in the period of the PWM signal, pseudo-randomly selecting a duty cycle for each PWM cycle using one or more look-up tables and generating the PWM signal based on the duty cycle.

Pseudo-random pulse width modulation for high resolution fan control

A circuit for temperature sensing provides a bias current to a PN junction, and the PN junction provides a PN junction voltage in response to the bias current. Also, a parasitic resistance may be coupled in series with the PN junction. The circuit for temperature sensing is configured to determine the temperature of the PN junction based on the PN junction voltage. Further, the circuit includes registers which store &#x3b7;trim, which is based on the difference between the non-ideality of the PN junction used from a reference PN junction; &#x394;I, which is based on the difference between a reference bias current and the bias current for the part; Rtrim, which is based the parasitic resistance; and Ntrim, which includes other offsets. The registers may be set during trimming and/or calibration to provide accurate temperature sensing for the parameters employed.

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San Jose, CA, United States of America

Eric Tam