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Linear Voltage Fan Speed Control Using Microchip's TC64X Family

From Microchip Technology, Inc.
 

 
Pulse Width Modulation (PWM) fan speed control methodology pulse-width modulates a fan's full-rated power supply voltage at a low frequency, typically 30 Hz. A typical PWM circuit, consisting of a transistor in series with a fan, can be small and inexpensive because it is either fully on or completely off. This efficient control methodology affords a very wide speed control range (typically 10% to 100% of full speed) because the fan motor is exposed to its full-rated voltage during the active portion of the PWM cycle. PWM control works with standard, two-wire Brushless DC (BDC) fans of various sizes. However, very large fans (with operating currents of 0.5A or more) can sometimes produce an unwanted acoustic noise component when operated with PWM control. In most cases, this is remedied by slowing the edges of the output switching transistor with the addition of a small capacitor. In the most severe cases, this may not be sufficient, which forces the user to consider linear voltage speed control.
Product Announcements
JMC Products - Pulse Width Modulated DC Fans
JMC offers a host of high frequency Pulse Width Modulated (PWM) fans that perform at low noise levels by eliminating the power switching noise of the fan. The speed of the fan is controlled by an... (read more)
JMC Products - 4-Wire PWM for Cost Reduction
JMC offers customers a cost reduced 4-wire PWM fan that uses the PWM signal to directly drive a circuit to the motor coils. This results in 0 RPM when the duty cycle is below 5~8%, initial rotation... (read more)
Pelonis Technologies, Inc. - Heavy Duty DC Automotive Fans!
Pelonis Technologies manufactures Condensation/Evaporation automotive fans which are suitable for buses, trucks, commercial, construction, and public transport vehicles. Available in various DC... (read more)
Dart Controls, Inc. - Pulse Width Modulated DC Speed Control
DPW Series: Pulse width modulated DC Motor Speed Controls... (read more)
Bodine Electric Company - New, Larger INTEGRAmotors from Bodine Electric
The new 34B/FV type, 24V brushless DC INTEGRAmotor™ gearmotors and motors combine a PWM speed control, a brushless DC motor, an optical encoder, and a gearhead into one innovative drive solution... (read more)
ELMA Electronic Inc. - 5U AdvancedTCA chassis from ELMA
Elma Electronic Inc., a global manufacturer of electronic packaging products, has announced a new 5U AdvancedTCA chassis with full redundancy. There are dual redundant fan trays, shelf managers, and... (read more)
TCI, LLC (Trans-Coil International) - KMG GP Sinewave Output Filter
KMG design in a General Purpose / NEMA 3R Enclosure: With the same level of performance as the original KMG Industrial Filter!... (read more)
TCI, LLC (Trans-Coil International) - KMG High Performance Motor Protection Filter
Converts the PWM waveform to near sinusoidal - required for sensitive applications. (read more)
Topics of Interest
Brushless DC fan (BDC) speed can be varied using pulse-width modulation (PWM). The typical PWM control scheme inserts a power switch in series with the fan, as shown in Figure 1. In such applications,... (Read More)
Microchip's TC642, TC643, and TC646 are the world's first integrated circuits dedicated for controlling and monitoring fan speed. The new family of fan speed controllers modulate fan speed to... (Read More)
The PIC17C42 is equipped with two high frequency Pulse Width Modulation (PWM) outputs. In a pulse width modulated signal the period of the signal is (usually) kept fixed, while the duty cycle is... (Read More)
DC brushless cooling fans have a history of effectively cooling electronic circuits. Today, DC brushless cooling fans are found in new applications and are being evaluated by engineers that may not... (Read More)
When the output voltage (VO) of a DC/DC converter must be adjusted in an application, the manufacturer usually specifies the output adjustable voltage range of the converter, typically 5% to 10%. The... (Read More)