SmartFan® Multi SD DC Fan Speed Controller and Alarm

  • Temperature Driven Fan Speed Control for 12, 24, 48V Fans

  •    5 Amp Rating
  •    Can be used with TachScan Fan Alarm Products
  •    Factory Customization for Orders as Low as 50 Pieces
Operation / Installation PDF

Multi SD Datasheet

SmartFan® Multi SD fan speed controller is designed for controlling 2 wire DC fans and blowers in electronics cooling applications. Fan speed control is based on sensing temperature from up to 3 OR’d sensors and varying fan voltage using a current mode buck control circuit.  Multi SD accepts single or dual 10-75 VDC power feeds to control 12, 24 or 48 VDC fans at a high frequency achieving maximum power efficiency in a minimum package size.  Customer selectable parameters include; fan voltage, control temperature and 1, 2 or 3 temperature sensors.   All Multi SD fan speed controllers are supplied with an optically isolated temperature alarm triggered if a sensor reaches 10°C above the selected control temperature or if cooling system power is lost. By adding a compatible SmartFan®TachScan 3 or TachScan 9  fan speed alarm, one can also control and monitor up to nine 3 wire fans (DC fans equipped with tach pulse 3rd wire).

Contact Control Resources customer service to ask about modifying the Multi SD for your application or for designing custom products from the ground up to meet your specification.   Factory customization is available for orders as low as 50 pieces.


Specifications Features
  • » Supply voltage: 10-75 VDC, single or dual diode OR’d
  • » Soft start and current limiting at start up
  • » Current Rating: 4 Amps @ 55°C or less, 5 Amps in air-flow (200 ft/min)
  • » Operating temperature: -20°C to 55°C full power, derated up to 70°C
  • » Storage temperature: -40°C to 125°C
  • » Weight: 1.9 oz. (54 grams)
  • » Size: 1.5″ X 5.0″
  • » RoHS compliant
  • recognized to UL508 and CSA-C22.2, File E100344
  • » High power efficiency: typically greater than 90%
  • » Noise reduction: typically 15 dB(A) or more at idle speed
  • » Jumpers allow user selectable fan speed control settings of:
    • – 12, 24 or 48 VDC operation (maximum output is limited to input voltage)
    • – 35, 40 or 45°C Control Temperature
    • – 1, 2 or 3 temperature sensors
  • » Accepts up to three OR’d temperature sensors
  • » Compatible with 8 SmartFan temperature sensors
  • » Compatible with TachScan fan speed alarms
  • » Temperature alarm output through optical isolator or MOS relay

SmartFan Multi SD Fan Control & Alarm Dimensions and Connections

Multi SD Dims 62615


For CAD drawings, use the links in Additional Information below.

SmartFan Multi SD Fan Control & Alarm Part Numbers

Part Number Supply Voltage Range Maximum Wattage at 55°C Isolated Temperature
Alarm Sinking Current
200 Ft/Min Still Air
042D440-F1 10 to 75 VDC 240 Watts/5.0 Amps 192 Watts/4.0 Amps 1 mA
042D440R-F1 100 mA
H118-F Hardware Pack

1. Temperature sensor required. See sensors page.

Additional Information

» Multi SD Operation / Installation Datasheet (PDF)
» Multi SD IGS CAD drawing (.igs)
» SmartFan Price List (PDF)
» Click here for Questions or Comments

To talk to an Engineer or Service Representative, call (978) 486-4160 (9:00 AM – 5:00 PM EST)

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Initially designed for our own engineering lab, CRI also offers versatile, low cost test equipment for test benches, laboratories, field work and repair facilities.