OUTPUT VOLTAGE (V) LTC1695 2 SMBus/I C Fan Speed Controller in SOT-23 FEATURES DESCRIPTIO TM 2 n Complete SMBus/I C Brushless DC Fan Speed The LTC 1695 fan speed controller provides all the func- Control System in a 5-Pin SOT-23 package tions necessary for a power management microprocessor n 0.75W PMOS Linear Regulator with 180mA to regulate the speed of a 5V brushless DC fan via a 2-wire 2 Output Current Rating SMBus/I C interface. Fan speed is controlled according to n 0V to 4.922V Output Voltage Range Controlled by a the systems required temperature profile and permits 6-Bit DAC lower fan power consumption, longer battery run time and 2 n Simple 2-Wire SMBus/I C Interface lower acoustical generated noise versus systems that n 250ms Internal Timer Ensures Fan Start-Up only provide simple on-off control for the fan. n Current Limit and Thermal Shutdown The LTC1695 incorporates a 180mA low dropout linear n Fault Status Indication via SMBus Host Readback 2 regulator, a 2-wire SMBus/I C interface and a 6-bit DAC. Fan speed is controlled by varying the fans terminal U voltage through the output voltage of the LTC1695s linear APPLICATIO S regulator. The LTC1695s output voltage is programmed n Notebook Computers by sending a 6-bit digital code to the LTC1695 DAC via the n Spot Cooling SMBus. To eliminate fan start-up problems at lower fan n Portable Instruments voltages, users can enable the LTC1695s boost start n Battery-Powered Systems feature that provides the DACs full-scale output voltage n DC Motor Control for 250ms before decreasing to the programmed output n White LED Power Supplies voltage. n Programmable Low Dropout Regulator 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 , LTC and LT are registered trademarks of Linear Technology Corporation. 2 I C is a trademark of Philips Electronics N.V. LTC1695 is available in a 5-lead SOT-23 package. TYPICAL APPLICATION Fan Voltage and Current vs DAC Code 120 6 V = 5V CC T = 25C A 100 5 5V 15 80 4 V V CC OUT + I LOAD 5V DC FAN V OUT 10m F LTC1695 + SUNON 60 3 2 4.7m F KDE0502PFB2-8 GND 0.6W, 1.7 CFM 3 (25 25 10)mm 40 2 3 4 SCL SDA SYSTEM 20 1 CONTROLLER 1695 TA01 0 0 40 60 70 0 10 20 30 50 DAC CODE 1695 TA02 1 LOAD CURRENT (mA) U ULTC1695 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW ORDER PART Terminal Voltages NUMBER V 1 5 V Supply Voltage (V ) ............................................. 7V CC OUT CC GND 2 All Other Inputs ........................ 0.3V to (V + 0.3V) CC LTC1695CS5 SCL 3 4 SDA Operating Temperature Range ..................... 0 C to 70 C Junction Temperature........................................... 125 C S5 PACKAGE 5-LEAD PLASTIC SOT-23 Storage Temperature Range .................. 65 C to 150 C S5 PART MARKING T = 125 C, q = 256 C/W JMAX JA Lead Temperature (Soldering, 10 sec).................. 300 C SEE THE APPLICATIONS LTIY INFORMATION SECTION. Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25 C. V = 5V unless otherwise stated. A CC SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Supply Voltage Range 4.5 5 5.5 V CC I Supply Current, Operating V = Full Scale, I = 150mA l 150.7 155 mA CC OUT LOAD Supply Current, Shutdown DAC Code = 0 l 80 200 m A DAC DAC Resolution Guaranteed Monotonic l 6 Bits V 1LSB Resolution I = 1mA l 73 78 83 mV LSB LOAD V Offset Error I = 1mA l 1 LSB OS LOAD DNL Differential Nonlinearity I = 1mA (Note 2) l 0.75 LSB LOAD INL Integral Nonlinearity I = 1mA (Note 2) l 0.75 LSB LOAD V V , DAC Full Scale I = 20mA l 4.5 4.93 V FS OUT LOAD I = 150mA l 4.5 4.9 V LOAD V V , DAC Zero Scale R = 1kW l 085 mV ZS OUT LOAD R P-Channel On Resistance I = 150mA 0.75 W ON(P) LOAD Timer and Thermal Shutdown V Undervoltage Lockout Voltage Rising V l 2.3 2.9 3.5 V UVLO CC T Boost Start Timer I = 10mA, C = 4.7m F l 75 250 1000 ms BST ST LOAD LOAD T Thermal Shutdown Temperature (Note 3) 155 C THERMAL I Output Current Limit Threshold V = 0V, DAC Code = 63 l 180 390 850 mA FAULT OUT SMBus SCL, SDA Inputs V Input High Threshold l 2.1 V IH V Input Low Threshold l 0.8 V IL I Input Current SCL, SDA = 0V or 5V l 0.1 5 m A IN C Input Capacitance (Note 3) 3 pF IN t Switch On Time from V from Zero Scale to Full Scale, l 50 500 m s ON OUT Stop Condition (f = 100kHz) I = 1mA, C = 4.7m F SMBus LOAD LOAD t Switch Off Time from V from Full Scale to Zero Scale, l 150 500 m s OFF OUT Stop Condition (f = 100kHz) I = 150mA, C = 4.7m F SMBus LOAD LOAD V SDA Output Low Voltage I = 3mA l 150 400 mV OL PULLUP 2 U WWW