特点
Complete SMBus/I2C? Brushless DC Fan Speed
Control System in a 5-Pin SOT-23 package
0.75Ohms PMOS Linear Regulator with 180mA
Output Current Rating
0V to 4.922V Output Voltage Range Controlled by a
6-Bit DAC
Simple 2-Wire SMBus/I2C Interface
250ms Internal Timer Ensures Fan Start-Up
Current Limit and Thermal Shutdown
Fault Status Indication via SMBus Host Readback
典型应用
典型应用
描述
描述 The LTC?1695 fan speed controller provides all the functions necessary for a power management microprocessor to regulate the speed of a 5V brushless DC fan via a 2-wire SMBus/I2C interface. Fan speed is controlled according to the system’s required temperature profile and permits lower fan power consumption, longer battery run time and lower acoustical generated noise versus systems that only provide simple on-off control for the fan. The LTC1695 incorporates a 180mA low dropout linear regulator, a 2-wire SMBus/I2C interface and a 6-bit DAC. Fan speed is controlled by varying the fan’s terminal voltage through the output voltage of the LTC1695’s linear regulator. The LTC1695’s output voltage is programmed by sending a 6-bit digital code to the LTC1695 DAC via the SMBus. To eliminate fan start-up problems at lower fan voltages, users can enable the LTC1695’s boost start feature that provides the DAC’s full-scale output voltage for 250ms before decreasing to the programmed output voltage. The LTC1695 includes output current limiting and thermal shutdown as well as status monitors that can be read back by the microprocessor during fault conditions. The LTC1695 is available in a 5-lead SOT-23 package.