Features and Benefits

  • Complete SMBus/I²C Brushless DC Fan Speed Control System in a 5-Pin SOT-23 package
  • 0.75Ω PMOS Linear Regulator with 180mA Output Current Rating
  • 0V to 4.922V Output Voltage Range Controlled by a 6-Bit DAC
  • Simple 2-Wire SMBus/I²C Interface
  • 250ms Internal Timer Ensures Fan Start-Up
  • Current Limit and Thermal Shutdown
  • Fault Status Indication via SMBus Host Readback

Product Details

The LTC1695 fan speed controller provides all the functions necessary for a power management microprocessor to regulate the speed of a 5V brushless DC fan via a 2-wire SMBus/I²C interface. Fan speed is controlled according to the system’s required temperature profile and permits lower fan power consumption, longer battery run time and lower acoustical generated noise versus systems that only provide simple on-off control for the fan.

The LTC1695 incorporates a 180mA low dropout linear regulator, a 2-wire SMBus/I²C interface and a 6-bit DAC. Fan speed is controlled by varying the fan’s terminal voltage through the output voltage of the LTC1695’s linear regulator. The LTC1695’s output voltage is programmed by sending a 6-bit digital code to the LTC1695 DAC via the SMBus. To eliminate fan start-up problems at lower fan voltages, users can enable the LTC1695’s boost start feature that provides the DAC’s full-scale output voltage for 250ms before decreasing to the programmed output voltage.

The LTC1695 includes output current limiting and thermal shutdown as well as status monitors that can be read back by the microprocessor during fault conditions. The LTC1695 is available in a 5-lead SOT-23 package.


  • Notebook Computers
  • Spot Cooling
  • Portable Instruments
  • Battery-Powered Systems
  • DC Motor Control
  • White LED Power Supplies
  • Programmable Low Dropout Regulator

Product Lifecycle icon-recommended Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Evaluation Kits (1)

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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.