MAX31760 Precision Fan-Speed Controller with Nonvolatile Lookup Table General Description Features The MAX31760 integrates temperature sensing along Operating Settings Stored in Nonvolatile Memory for with precision PWM fan control. It accurately measures Automatic Operation at Power-On its local die temperature and the remote temperature of 48-Step Nonvolatile LUT Maps Temperature to PWM a discrete diode-connected transistor, such as a 2N3906, Duty Cycle or a thermal diode commonly found on CPUs, graphics Smooth PWM Duty-Cycle Transitions Minimize processor units (GPUs), and other ASICs. Multiple tem- Audibility of Fan Noise perature thresholds, such as local high/overtemperature Two Tachometer Inputs for Measuring the RPM of (OT) and remote high/overtemperature, can be set by an Two Fans Independently 2 I C-compatible interface. FF/FS Pin Multiplexes Fan-Failure Output with Full- Fan speed is controlled based on the temperature reading Speed Fan-Drive Input as an index to a 48-byte lookup table (LUT) containing Accurately Senses Remote and Local Temperature user-programmed PWM values. The flexible LUT-based Programmable Thermal Diode Ideality Factor architecture enables the user to program a smooth Minimizes Ideality Factor Mismatch nonlinear fan speed vs. temperature transfer function to minimize acoustic fan noise. Two tachometer inputs allow Automatic Series Resistance Cancellation measuring the speeds of two fans independently. The Dedicated ALERT Pin for Temperature Faults FF/FS pin multiplexes an open-drain fan-failure output SHDN Pin Available for System Overtemperature with a full-speed fan-drive input. When the local or remote Shutdown OT threshold is exceeded, the SHDN pin is asserted low 3.0V to 3.6V Operating Voltage Range and can be used to shut down the system. A dedicated -40NC to +125NC Operating Temperature Range ALERT pin reports that either a local or remote high- temperature threshold has been exceeded. ALERT can Applications be programmed to work in either fault indicator mode or interrupt mode. These features make the device a com- Servers pact and complete solution for a single-fan or two-fan Networking Equipment cooling system. STB/DVR NAS/DAS Ordering Information appears at end of data sheet. Typical Application Circuit +3.3V FAN VOLTAGE +5V OR +12V V CC 4-WIRE FAN 1 V DD ALERT TACH1 TACH FF/FS TACH2 PWM SHDN GND MAX31760 SDA PWM TO SYSTEM HOST SCL FAN VOLTAGE +5V OR +12V DXP VCC 4-WIRE FAN 2 2200pF TACH DXN PWM REMODE A0 A1 A2 GND DIODE CONNECTED GND TRANSISTOR (e.g., CPU, GPU, OR ASIC) For related parts and recommended products to use with this part, refer to www.maximintegrated.com/MAX31760.related. 19-7395 Rev 0 4/14MAX31760 Precision Fan-Speed Controller with Nonvolatile Lookup Table Absolute Maximum Ratings V to GND .........................................................-0.3V to +6.0V Continuous Power Dissipation (T = +70C) DD A SCL, SDA, ALERT, FF/FS, SHDN, QSOP (derate 9.6mW/C above +70C) .................771.5mW TACH1, TACH2 and PWM to GND ..................-0.5V to +6.0V ESD Protection (All Pins, Human Body Model) ................Q2kV DXP, DXN, A0, A1, and A2 to GND ......... -0.3V to (V + 0.3V), Operating Temperature Range ......................... -40C to +125C DD not to exceed +6.0V Junction Temperature ......................................................+150C SCL, SDA, ALERT, FF/FS, SHDN, PWM Current ...............8mA Storage Temperature Range ........................... -65C to +150C DXN Current ......................................................................200A Lead Temperature (soldering, 10s) .................................+300C Soldering Temperature (reflow) .......................................+260C 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. (Note 1) Package Thermal Characteristics QSOP Junction-to-Ambient Thermal Resistance ( ) .....103.7C/W JA Junction-to-Case Thermal Resistance ( ) ...............37C/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 DC Operating Conditions (T = -40C to +125C, unless otherwise noted.) (Note 2) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS V Voltage V (Note 3) 3.0 3.3 3.6 V DD DD Input Logic 0 (SDA, SCL) -0.3 +0.8 V V V x IL DD Input Logic 0 (All Other Inputs) -0.3 0.3 V + DD Input Logic 1 (SDA, SCL) 2.1 0.3 V V IH V x V + DD DD Input Logic 1 (All Other Inputs) 0.7 0.3 Electrical Characteristics (3.0V V 3.6V, T = -40C to +125C, unless otherwise noted.) DD A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS I Normal operation 2.6 4 mA DD Supply Current I Standby mode 2 3 mA STB Internal Temperature T = -40C to +125C 0.125 C A Measurement Resolution External Temperature T = -40C to +125C 0.125 C A Measurement Resolution Conversion Time t Both internal and external channels 150 ms CONV Maxim Integrated 2 www.maximintegrated.com