The MAX6650/MAX6651 fan controllers use an SMBus™/I2C™-compatible interface to regulate and monitor the speed of 5VDC/12VDC brushless fans with built-in tachometers. They automatically force the fan's tachometer frequency (fan speed) to match a preprogrammed value in the Fan-Speed Register by using an external MOSFET or bipolar transistor to linearly regulate the voltage across the fan. The MAX6650 regulates the speed of a single fan by monitoring its tachometer output. The MAX6651 also regulates the speed of a single fan, but it contains additional tachometer inputs to monitor up to four fans and control them as a single unit when they are used in parallel.
The MAX6650/MAX6651 provide general-purpose input/output (GPIO) pins that serve as digital inputs, digital outputs, or various hardware interfaces. Capable of sinking 10mA, these open-drain inputs/outputs can drive an LED. To add additional hardware control, configure GPIO1 to fully turn on the fan in case of software failure. To generate an interrupt when a fault condition is detected, configure GPIO0 to behave as an activelow alert output. Synchronize multiple devices by setting GPIO2 (MAX6651 only) as an internal clock output or an external clock input.
The MAX6650 is available in a space-saving 10-pin µMAX package, and the MAX6651 is available in a small 16-pin QSOP package.
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RAID Desktop ComputersServers NetworkingWorkstations Telecommunications
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Closed/Open-Loop Fan-Speed Control for 5V/12V Fans 2-Wire SMBus/I2C-Compatible Interface Monitors Tachometer OutputSingle Tachometer (MAX6650)Up to Four Tachometers (MAX6651) Programmable Alert Output GPIOs Hardware Full-On Override Synchronize Multiple Fans Four Selectable Slave Addresses 3V to 5.5V Supply Voltage Small Packages10-Pin µMAX (MAX6650)16-Pin QSOP (MAX6651)
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VCC to GND..............................................................-0.3V to +6V
FB, TACH_ ..........................................................-0.3V to +13.2V
All Other Pins..............................................-0.3V to (VCC + 0.3V)
Output Voltages.........................................-0.3V to (VCC + 0.3V)
Maximum Current
Into VCC, GND, VOUT.......................................................100mA
Into All Other Pins .............................................................50mA
Continuous Power Dissipation (TA = +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW
16-Pin QSOP (derate 8.3mW/°C above +70°C)...........667mW
Operating Temperature Range ......................-40°C to +85°C
Junction Temperature ..................................................+150°C
Storage Temperature Range .......................-65°C to +150°C
Lead Temperature (soldering, 10s) .............................+300°C
Post a Buying Lead
Required Field 
