LTC1840

U U FEATURES s Two 8-Bit Current DACs s DACs Guaranteed Monotonic s Known IC State on Power-Up s Serial Interface Watchdog Timer with Disable s 2-Wire Serial Interface Compatible with I2CTM and SMBus s 2 Programmable Fan Tachometer Interfaces s 4 Programmable General Purpose I/Os s Small 16-Pin SSOP Package s Single 2.7V to 5.75V Supply Operation s Fault Output Signal s Status Register s Fan Blasting Function s Nine Addresses Using Two Programming Lines U APPLICATIO S s Servers s Desktop Computers s Power Supplies s Cooling Systems , LTC and LT are registered trademarks of Linear Technology Corporation. I2C is a trademark of Philips Electronics N.V. LTC1840 Dual Fan Controller with 2-Wire Interface DESCRIPTIO The LTC®1840 is a fan controller with two 8-bit current output DACs, two tachometer interfaces, and four general purpose I/O (GPIO) pins. It operates from a single supply with a range of 2.7V to 5.75V. A current output DAC is used to control an external switching regulator, which controls the fan speed. A current output DAC and tachometer allow a controller to form a closed control loop on fan velocity. The GPIO pins can be used as digital inputs or open drain pull-down outputs. The part features a simple 2-wire I2C and SMBus compatible serial interface that allows communication between many devices. The interface includes a fault status register that reflects the state of the part and which can be polled to find the cause of a fault condition. Other operational charac...