eum6861/a/b/c ds6861/a/b/c ver1.4 feb. 2012 1 18v pwm fan motor driver description eum6861/a/b/c is a fan motor driver for the single coil brushless dc motor. with its high efficient di rect pwm control mode, eum6861/a/b/c controls the speed of brushless dc motor with a built in hall ic interface. eum6861/a/b/c is suitable to drive varia ble speed motors for personal computers power supply radiation fans and cpu coolers. eum6861/a/b/c integrates pwm fan speed control, minimum speed mode, soft start, fan tachometer, loc k protection, auto restart and hall bias functions. p wm mode controls fan speed in low noise and low vibrat ion ways by adjusting rctl voltage. eum6861/a/b/c can set minimum fan speed by presetting rmin voltage. with soft start function, eum6861/a/b/c ca n drive motor from slow speed to fast speed in a sett able time by setting the external capacitor between ss a nd gnd. if a fan motor is stalled by the external forc e or obstacles, overdrive current may incur coil overhea t and burning. to prevent motor from overheating, the lock protection circuit shuts down the internal pow er devices for a few seconds after the motor lock is detected. then the auto restart circuit resumes to power up the internal power devices. if the lock persists , eum6861/a/b/c shuts off power devices for a few seconds. the lock protection delay time is external ly programmable by a capacitor. eum6861/c has built in motor rotation speed feedback (fg) output, motor rotation detection (rd) output and hall sensor bias output. application circuit features built in 18v full-wave motor driver for fan motor built in input surge protection, no zener diode need external programmable soft start and soft restart function wide input range 3v~18v pwm fan speed control programmable minimum fan speed built in soft switching function built in hall bias lock protection and auto restart fan rotation speed feedback fg output (eum6861/b/c) fan rotation detection rd output (eum6861/a/c) thermal shutdown protection available in tssop-16 and tdfn-14 packages rohs compliant and 100% lead (pb)-free halogen-free applications personal computers power supply radiation fans and cpu coolers figure 1. tssop -16 typical application circuit
eum6861/a/b/c ds6861/a/b/c ver1.4 feb. 2012 2 application circuit (continued) figure 2. tdfn-14 typical application circuit functional block diagram figure 3. functional block diagram
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