LTC1695 - SMBus/I²C Fan Speed Controller in SOT-23


  • Complete SMBus/I²C™ Brushless DC Fan Speed
    Control System in a 5-Pin SOT-23 package
  • 0.75Ohms 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

Typical Application

LTC1695 Typical Application
LTC1695 Typical Application


The LTC®1695 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.


CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
LTC1695CS5#PBF SOT-23 S5 C 05-08-1635 Yes
LTC1695CS5#TRMPBF SOT-23 S5 C 05-08-1635 Yes
LTC1695CS5#TRPBF SOT-23 S5 C 05-08-1635 Yes

LTC1695 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
LTC1695CS5#PBF SOT-23 C $1.81 Yes
LTC1695CS5#TRMPBF SOT-23 C $1.81 $1.53 Yes
LTC1695CS5#TRPBF SOT-23 C $1.81 $1.51 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC285A LTC1695CS5 | SMBus Fan Speed Controller (req. DC1223) $75.00
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Companion Boards

Part Number Description Price Documentation
DC1223A-B USB to SM-Bus/SPI Interface with Monitor $400.00
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Click here to view our complete list of demo boards


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