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) https://elecena.pl/product/22331537/fan-speed-regulators-and-monitors-with-smbus-i-c-compatible-interface 2022-12-28 https://elecena.pl/product/22331537/fan-speed-regulators-and-monitors-with-smbus-i-c-compatible-interface 2025-01-20