92111 sy 20110915-s00002/31407 ti pc 20070206-s00002 b8-6878 no.8793-1/7 http://onsemi.com semiconductor components industries, llc, 2013 may, 2013 lb11961 overview the lb11961 is a single-phase bipolar dr ive motor driver that easily implements direct pwm motor drive systems with excellent efficiency. the lb11961 is op timal for fan motor drive in personal computer power supply systems and cpu cooling fan systems. features ? single-phase full-wave drive (16v, 1.0a transistors are built in) ? built-in variable speed function controlled by a thermistor input the lb11961 can implement quiet, low-vibration variable speed control using externally clocked high side transistor direct pwm drive. ? built-in regenerative diode (di) ; only requires a minimal numb er of external components. ? built-in hb ? minimum speed setting pin (allows full-speed mode operation at startup) ? operates in full-speed mode when the thermistor is removed. ? built-in lock protection and automatic recovery circuits ? fg (speed detection) and rd (lock detection) outputs ? built-in thermal shutdown circuit monolithic digital ic single-phase full-wave fan motor driver orderin g numbe r : en8793b
lb11961 no.8793-2/7 specifications absolute maximum ratings at ta = 25 c parameter symbol conditions ratings unit v cc maximum output voltage v cc max 18 v out pin maximum output current i out max 1.0 a out pin output voltage v out max 18 v hb maximum output current ihb max 10 ma vth input pin voltage vth max 6 v rd/fg output pin output voltage vrd/fg max 18 v rd/fg output cu rrent ird/fg max 10 ma allowable power dissipation pd max when mounted on a circuit board *1 1.1 w operating temperature topr -30 to +90 c storage temperature tstg -55 to +150 c *1 specified circuit board : 114.3 76.1 1.6mm 3 , glass epoxy. caution 1) absolute maximum ratings represent the va lue which cannot be exceeded for any length of time. caution 2) even when the device is used within the range of abso lute maximum ratings, as a result of continuous usage under hig h temperature, high current, high voltage, or drastic temperature change, the reliability of th e ic may be degraded. please contact us for the further detai ls. recommended operating conditions at ta = 25 c parameter symbol conditions ratings unit v cc supply voltage v cc 4.5 to 16 v vth input level voltage range vth 0 to 9 v hall sensor input common-mode input voltage range vicm 0.2 to 3 v electrical characteristics unless otherwise specified ta = 25 c, v cc = 12v ratings parameter symbol conditions min typ max unit i cc 1 drive mode 12 18 24 ma circuit current i cc 2 lock protection mode 8 11 16 ma 6vreg voltage v6vreg i6vreg = 5ma 5.8 6 6.2 v hb voltage vhb ihb = 5ma 1.10 1.25 1.40 v cpwm high-level voltage vcrh 3.45 3.6 3.75 v cpwm low-level voltage vcrl 1.95 2.05 2.15 v cpwm oscillator frequency fpwm c = 100pf 18 25 32 khz ct pin high-level voltage vcth 3.45 3.6 3.75 v ct pin low-level voltage vctl 1.55 1.7 1.85 v ict charge current ict1 1.5 2 2.5 a ict discharge current ict2 0.15 0.2 0.25 a ict charge/discharge current ratio rct 8.5 10 11.5 out output low saturation voltage v ol i o = 200ma 0.2 0.3 v out output high saturation voltage v oh i o = 200ma 0.9 1.1 v hall sensor input sensitivity vhn zero peak value (including offset and hysteresis) 10 20 mv rd/fg output pin low-level voltage vrdl/fgl ird/fg = 5ma 0.2 0.3 v rd/fg output pin leakage current irdl/fgl vrd/fg = 7v 30 a stresses exceeding maximum ratings may damage the device. maximum ratings are stress ratings only. functional operation above the recommended oper ating conditions is not implied. extended exposure to stresses above the recommended operating conditions may affect device reliabili ty.
lb11961 no.8793-3/7 package dimensions unit : mm (typ) 3313 truth table vth in- in+ cpwm ct out1 out2 fg rd mode high low high low low low (open) low high high low high off during rotation ? drive (pwm off) high low off low low high low high low low low off off on during rotation ? regeneration (pwm on) - high low high off low - low high - high off high off off lock protection cpwm ? high is the state where cpwm > vth, and cpwm? low is the state where cpwm < vth. open : the lb11961 operates in full-speed mode when the ther mistor is removed. 0 0.8 0.4 0.2 0.6 1.0 1.2 1.1 ? 30 ? 10 90 50 70 10 30 110 0.53 ambient temperature, ta ? c allowable power dissipation, pd max ? w pd max ? ta specified circuit board : 114.3 76.1 1.6mm 3 glass epoxy board sanyo : hssop14(225mil) 6.5 6.4 4.4 0.22 0.65 1.3 (2.35) 1.5 17 8 14 0.1 1.5max (1.3) 0.5 0.15
lb11961 no.8793-4/7 pin assignment f-gnd (p-gnd) : the motor system ground and the heat sink. since the heat generated since the heat generated by the chip is dissipated through f-gnd, the thermal re sistance is lowered by increasing the area of the copper foil and solder surface in the printed circuit pattern. s-gnd : control system ground block diagram amplifier with hysteresis hall cpwm p-gnd m control circuit in ? in + v cc out1 fg out2 delay circuit delay circuit vth s-gnd 6vreg rd constant voltage oscillator circuit charge/discharge circuit 1.3v hb thermal protection circuit ct top view f-gnd (p-gnd) f-gnd (p-gnd) lb11961 rmi vth cpwm fg 7 1 2 13 10 9 3 out2 in- hb 6vreg s-gnd 12 11 5 14 ct 4 6 8 out1 rd in+ v cc
lb11961 no.8793-5/7 application circuit example *1. power supply and ground lines p-gnd is connected to the motor power supply system and s-gnd is connected to the control circuit power supply system. these two systems should be formed from se parate lines and the control system exte rnal components shoul d be connected to s-gnd. *2. regeneration power supply stabilization capacitor the capacitor cm provides power supply stabilization for both pwm drive and kickback absorption. a capacitor with a value of over 0.1f is used for cm. a large capacitor must be used when the coil inductance is la rge or when the coil resistance is low. since this ic adopts a technique in which switching is performed by the high side transistor and regeneration is handled by the low side transistor, the pattern connecting cm to vm and p-gnd must be as wide and as short as possible. *3. hall sensor input lines that are as short as possible must be used to prevent noise from entering the system. th e hall sensor input circuit cons ists of a comparator with hysteresis (20mv). we recommend that the hall se nsor input level be at least th ree times this hysteresis, i.e . at least 60mvp-p. *4. pwm oscillator frequency setting capacitor if a value of 100pf is used for cp, the os cillator frequency will be f = 25khz, and this will be the basic frequency of the p wm signal. *5. rd output this is an open collector output. it outputs a low level when th e motor is turning and a high level when it is stopped. this p in must be left open if unused. *6. fg output this is an open collector output, and a rotation count dete ction function can be implemente d using this fg output, which corresponds to the phase switching. this pin must be left open if unused. *7. hb pin this pin provides a hall effect sensor bias constant-voltage output of 1.25v. *8. rmi pin connect this pin to vth if unused. even if unused, the ic is set internally to ope rate at a 10% drive duty at the voltage corresponding to the lowest speed. (the capacitor is used to set up full-sp eed mode at startup.) f-gnd f-gnd v cc fg out1 out2 ct vth in + in ? cpwm * 3 cm * 1 * 6 h * 2 * 5 rmi rd hb * 8 s-gnd * 4 * 7 6vreg ct = 0.47 =
lb11961 no.8793-6/7 control timing chart 1. set minimum speed mode a vth voltage level is generated when the thermistor de tects the set temperature. at low temperatures, the fan motor turns at the lowest speed, which is set with th e rmi pin. the lb11961 compares the cpwm oscillator voltage with the rmi pin voltage and sets the duty for the lowest drive state. 2. high speed ? low speed mode the pwm signal is controlled by comparing the cpwm os cillation voltage that cycles between 1.2v and 3. 8v and the vth voltage. when the vth voltage is lower, the high and low side transistors are turned on, and when the vth voltage is higher, the high side transistor is turned off and the co il current is regenerated through the low side transistor. thus the output on duty increases as the vth voltage becomes lower, the coil current increases, and the motor speed increases. rotation speed feedback is provided by the fg output. 3. full-speed mode the lb11961 switches to full-speed mode above a certain temperature. 4. thermistor removed mode if the thermistor is removed, the vth input voltage will rise. however, the output will go to full drive at 100% and the motor will run at full speed. thermistor removed v cc cpwm 3.6v 2.0v pwm control variable speed mode full speed mode 0v 0v 12v f = 25khz (cp=100pf) low on duty high on duty fg set minimum speed rmi voltage internal lowest speed setting voltage (v cc 30%) (v cc 16%) (v cc 28%) high temperature low tem p erature
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