Fan-Speed Regulators and Monitors with SMBus/I²C-Compatible Interface

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 active-low 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.

Applications

* Computers: Desktop, Workstation, Server * Networking * RAID * Servers * Telecommunications * Workstations

* Closed/Open-Loop Fan-Speed Control for 5V/12V Fans

* 2-Wire SMBus/I²C-Compatible Interface

* Monitors Tachometer Output

* Single 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 Packages

* 10-Pin µMAX (MAX6650)

* 16-Pin QSOP (MAX6651)