Click here to ask about the production status of specific part numbers. MAX31740 Ultra-Simple Fan-Speed Controller General Description Features The MAX31740 is a sophisticated, yet easy-to-use fan- Self-Contained PWM Fan ControlNo Micro Needed speed controller. It monitors the temperature of an external Controls Speed of 2-, 3-, or 4-Wire Fans NTC thermistor and generates a PWM signal that can be Resistors Set Fan Control Characteristics used to control the speed of a 2, 3, or 4-wire fan. The fan control characteristics are set using external resistors, Smooth, Linearly Varying PWM Duty Cycle Minimizes Audibility of Fan Noise thereby eliminating the need for an external microcon- troller. Controllable characteristics include the starting Accurately Monitors External Thermistor Temperature temperature for fan control, PWM frequency, fan speed 3.0V to 5.5V Operating Voltage Range at low temperatures, and slope of the temperature-duty- -40C to +125C Operating Temperature Range cycle transfer function. AEC-Q100 qualified MAX31740ATA/VY+ Because the operating characteristics are selected by hardwired passive components, a simple, low-cost fan- Applications speed controller can be implemented without the need Consumer Equipment for firmware development. This can dramatically reduce Communications Equipmen t development time for the fan control function. Computing Equipment The MAX31740 is available in a 2mm x 3mm, 8-pin TDFN Industrial Equipment package. Ordering Information appears at end of data sheet. Typical Application Circuits 2-WIRE FAN-SPEED CONTROLLER 4-WIRE FAN-SPEED CONTROLLER V V DD DD R C R C ST B ST B V V DD DD R R B B VFAN SENSE D0 SENSE D0 R R D1 D1 FREQ FREQ C C F F VFAN MAX31740 MAX31740 DMIN DMIN TACH OR PWM OUT N PWM OUT LOCKED 33Hz 25kHz R R D2 D2 GND SLOPE GND SLOPE ROTOR R R SLOPE SLOPE 19-6697 Rev 3 12/20MAX31740 Ultra-Simple Fan-Speed Controller Absolute Maximum Ratings (All voltages relative to ground.) Storage Tempera ture Range ............................ -55C to +125C Voltage Range on V -0.3V to +6.0V Junction Temperature Maximum ..................................... +150C DD .............................................. Voltage Range on Any Non-Power Pin .... -0.3V to (V + 0.3V) Soldering Temperature (reflow) ....................................... +260C DD Operating Temperature Range ......................... -40C to +125C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Package Thermal Characteristics (Note 1) TDFN Junction-to-Ambient Thermal Resistance ( ) .......... 60C/W JA Junction-to-Case Thermal Resistance ( ) ............... 11C/W JC Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. Recommended Operating Conditions (T = -40C to +125C, unless otherwise noted.) (Note 2) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage V 3.0 3.3 5.5 V DD Logic 1 (D0) V V x 0.7 V + 0.3 V IH DD DD Logic 0 (D0) V -0.3 V x 0.3 V IL DD Electrical Characteristics (V = V to V , T = -40C to +125C, unless otherwis e noted.) (Notes 2, 3) DD DDMIN DDMAX A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS V = 3.3V 500 800 DD Supply Current (Note 4) I A DD V = 5.5V 750 1100 DD PWM Start Voltage (Note 5) V V = 3.3V -80 -40 +10 mV START DD Input Bias Current (SENSE) I T = +25C to +125C 19 nA BIAS A Internal DO Pulldown Resistor DO 20 60 100 k RLOAD Internal SLOPE Feedback R V = 3.3V, T = +25C 22 2.4 k FBK DD A Resistance (Note 6) Sawtooth Peak Voltage Offset V 12 mV FSOFFSET (Note 7) Sawtooth Peak Voltage V 0.4925 0.5 0.5075 x V FS DD R Capacitive Load SLOPE C 10 pF SLOPE (Note 8) PWM Output Low V I = 6mA 0.4 V OL SINK PWM Output High V I = -6mA V - 0.4 V OH SOURCE DD -6 10.5455 /C Hz F PWM Frequency PWM T = +25C to +125C -10 +10 FREQ A % T = -40C to +125C -20 +20 A Maxim Integrated 2 www.maximintegrated.com