brushless dc motor controller features ? open loop motor control ? tachometer output for closed loop motor control ? error amplifier and pwm speed comparator with full accessibility ? high noise immunity schmitt triggers on sensor inputs ? 6v reference supply for external sensors ? cycle-by-cycle current sensing ? static, or current limited dynamic, motor braking ? output enable delay on speed direction reversal ? enable input with fault sensing capability ? fault indicator output ? 60?300?or 120?240?electrical sensor spacing selection ? selectable pwm of top and bottom drivers or bottom drivers only ? cmos compatible motor outputs with drive capability ? selectable top driver polarity ? low power dissipation ? +10v to +18v power supply (v dd - v ss ) ? LS7560N, ls7561n (dip); LS7560N-sd, ls7561n-sd (skinny dip); LS7560N-s, ls7561n-s (soic); LS7560N-ts, ls7561n-ts (tssop) - see figure 1 - ? note: LS7560N/ls7561n are backward compatible with ls7560/ls7561 general description the LS7560N/ls7561n are designed to control three or four phase brushless dc motors in a closed or open loop con- figuration. the ic consists of a decoder which provides proper commutation sequencing, a frequency-to-pulse width convert- er and error amplifier for closed loop motor speed control, a pwm comparator and sawtooth oscillator for external driver power control and a 6v reference generator for supplying pow- er to motor sensors. also included is fault detection and in- dication, overcurrent sensing, dynamic motor braking, forward/ reverse input, sensor spacing selections and an enable input control. the overcurrent sense condition will disable all output drivers when using the LS7560N and only the bottom drivers when using the ls7561n. the ic operates from 10v to 18v and provides cmos com- patible outputs for interfacing with external power devices. operating below 10v will activate a fault indication output and disable all output drivers. input/output description : (see figure 2) sequence select input (pin 1 ) a high on this input selects 60?300?and a low selects 120? 240?electrical sensor separation. use of a 300?or 240?motor will cause opposite direction rotation as compared to a 60?or 120?motor. f/r input (pin 27) a high on this input selects forward direction and a low se- lects reverse direction. the motor drive outputs are disabled for 2 clock cycles at the onset of a direction change. march 2006 7560n-031006-1 s1, s2, s3 inputs (pins 24, 25, 26) hall sensor inputs which are decoded to determine the motor commutation sequence. an invalid input code disables all motor outputs. inputs have schmitt trigger buffers for noise immunity. brake input (pin 23) with the brake select input low, a high on the brake input forces the top drivers to an off condition and the bottom drivers to a pwm on condition. if the motor is under closed loop control, the loop must be opened and the error amplifier output connected to the error amp (-) input. by controlling the voltage at the error amp (+) input, the pwm duty cycle is controlled during braking (see fig- ure 8). this manner of braking prevents the bottom motor drivers from drawing excessive current, a condition which can occur during normal braking, when the bottom drivers are turned on un- conditionally. with the brake select input high, a high on the brake input unconditionally causes the top drivers to turn off and the bottom drivers to turn on. the brake function has priority over all other functions. brake select input (pin 22) a low on this input selects pwm control of braking and a high se- lects unconditional braking. enable input (pin 2) when the enable input is above v r /2, all output drivers are en- abled and when it is below v r /2.2, all output drivers are disabled. this input has a nominal hysteresis of 0.05v r , where v r is the in- ternally generated reference voltage available on pin 19. because the enable input is level sensitive, it can easily be used to control operation of the ic based on an analog fault condition. lsi/csi l si c o m p u t e r sy s t e m s , i n c . 12 3 5 w a l t w h i t m a n ro a d , m e l v ill e , n y 1 174 7 ( 631 ) 2 71 - 0 40 0 f a x ( 631 ) 2 7 1 - 0 4 0 5 LS7560N ls7561n 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 figure 1. pin connection diagram LS7560N sequence select enable fault indicator rc tachometer out error amp (+) error amp (-) oscillator error amp out current sense (+) current sense (-) out 6 out 5 out 4 out 3 out 2 out 1 v ss (-v) v r top driver polarity select pwm control brake select brake s1 s2 s3 f/r v dd (+v) hall sensors top view lsi u l a3800
error amplifier inputs (pins 6, 7) output (pin 8) for closed loop control, the tachometer output is applied through a resistor to the negative input of the error amplifier on pin 7. a speed control potentiometer is connected to the positive input of the error amplifier on pin 6. a parallel rc network is connected between the output of the error amplifier on pin 8 and pin 7. the amplifier, configured this way, enables the variable pulse width to be converted to a dc voltage which is used to control the motor speed. the potentiometer is used to set the desired motor speed. for open loop control, configure the error amplifier as a voltage follower by connecting pin 7 directly to pin 8 and do not connect the tachometer output signal to the error amplifier. top driver polarity select input (pin 20) a high on this input selects a high polarity to enable the top out- put motor drivers and a low selects a low polarity to enable the top output motor drivers. output drivers (pins 12, 13, 14, 15, 16, 17) each driver output provides a cmos compatible signal for driv- ing buffers/power transistors. the outputs are capable of sink- ing/sourcing 25ma with a 1.5v drop across the ic, at v dd = 12v. fault indicator output (pin 3) open drain output to provide sinking current for driving an ex- ternal device, such as a led, through an emitter follower (see figure 3) to indicate a malfunction condition. the output occurs under any of the following conditions: 1) overcurrent sense condition 2) enable input below v r / 2.2 3) invalid sensor code 4) chip power supply less than 9v 5) v r output less than 4.1v v r output (pin 19) 6v reference voltage output that can supply 20ma of current at v dd = 12v for powering input sensors. v dd (pin 28) supply voltage positive terminal. oscillator (pin 9) an external rc network is connected to this input to set the fre- quency of the sawtooth schmitt trigger oscillator. the sawtooth is applied to the pwm comparator along with the output of the er- ror amplifier. the output of the pwm comparator is a pulse width modulated signal which is used to vary the effective drive to the motor and, hence, the motor speed. overcurrent sense (pins 10, 11) the input to pin 10 comes from the high side of a fractional ohm current sensing resistor. the voltage at this input is compared to an internal 100mv reference. when the voltage exceeds the 100mv reference, an overcurrent condition exists and the out- put drivers are switched off until the end of the sawtooth os- cillator ramp-up. when the sawtooth switches low, the over- current condition is sampled, and if it no longer exists, the output drivers are switched on again. otherwise, the output drivers re- main off until the end of the next sawtooth. the input to pin 11 comes from the low side (gnd) of the current sensing resistor and connects to the low side of the internal 100mv reference. pwm control input (pin 21) a high on this input causes only the bottom drivers to be pulse width modulated. a low on this input causes both top and bot- tom drivers to have pwm. tachometer output (pin 5) the output of the frequency to pulse width converter is tied to this pin. the converter uses the three sensor inputs and external rc network to generate a variable frequency output with a fixed positive pulse width. rc input (pin 4) the external rc network connected to this input programs the positive pulse width of the frequency to pulse width converter. v ss (pin 18) supply voltage negative terminal. 7560n-030906-2 maximum ratings (voltages referenced to vss) symbol value unit power supply voltage v dd 20 v voltage at any input v in vs s - 0.5 to v r v operating temperature t a -25 to +85 ?c storage temperature t stg -65 to +150 ?c output drive sink/source current io 75 ma v r output source current i r 30 ma electrical characteristics v dd = 12v, r t = 47k w , c t = 0.001f, r s = 10k w , c s = 0.01f, r f = 5.6k w (see figure 3) t a = 25?c, unless otherwise specified parameter symbol min typ max unit reference voltage v r 5.7 6.0 6.35 v line regulation d v r - 100 200 mv v dd = 10v to 18v, i ref = 1.0ma temperature stability t a = 0?c to 70?c d v r - +/- 1.0 - % t a = 0?c to 85?c d v r - +/- 1.3 - % error amplifier: input offset voltage v io - 5 15 mv input current i in - 0 10 na input common mode voltage range v icr (0 to v r ) v open loop voltage gain (r l = 15k w ) a vol 70 80 - db common mode rejection ratio c mrr 60 - - db power supply rejection ratio p srr 60 - - db
parameter symbol min typ max unit output high state (r l = 15k w to ground) v oh v r - - v output low state (r l = 15k w to v r ) v ol - - 1.0 v output source or sink current io - - 1.0 ma oscillator: oscillator frequency f osc 21 24 27 khz percentage frequency change per volt d f osc d v - 0.4 1.0 %/v (v dd = 10v to 18v) f sawtooth high voltage v oscp - 3.8 4.5 v sawtooth low voltage v oscv 0.7 1.0 - v capacitor discharge current i d 0.6 1.0 2.5 ma logic inputs: input threshold voltage v ih 3.0 2.3 - v (pins 1, 20, 21, 22, 23, 24, 25, 26, 27) v il - 1.8 1.4 v brake and sensor (pins 23, 24, 25, 26) high state input current (v in = 4v) i ih -36 -27 -20 a low state input current (v il = 0v) i il -50 -40 -30 a sequence select, top driver polarity select, pwm control, brake select, and f/r select (pins 1, 20, 21, 22, 27) high state input current (v in = 4v) i ih -16 -12 -8 a low state input current (v il = 0v) i il -25 -17 -10 a enable input threshold voltage (pin 2) v ih 2.1 2.8 3.2 v hysteresis v h 0.2 0.3 0.4 v enable input current i in - - 10 na overcurrent sense comparator: input threshold voltage v ih 85 100 115 mv input current i in - - 10 na outputs: closed loop control section: tachometer out output high voltage (i source = 1.5ma) v oh v r - 0.8 v r - 0.5 v r - 0.3 v output low voltage (i sink = 5ma) v ol 0.18 0.27 0.40 v pulse width t w 95 105 115 s capacitor discharge current (rc terminal) i d 1.8 3 7.5 ma output drivers (pins 12, 13, 14, 15, 16, 17) sourcing 25ma v oh 9.5 10.5 11 v sourcing 50ma v oh 8 8.8 9.5 v sinking 25ma v ol 1.0 1.30 2.0 v sinking 50ma v ol 2.75 3.40 4.2 v switching times t r 30 45 60 ns (c l = 250pf) t f 35 50 65 ns switching times t r 100 150 200 ns c l = 1000pf) t f 130 180 230 ns fault output voltage (i sink = 2ma) v fo - - 0.5 v fault off-state leakage i f - 10 - na under voltage lockout: for v dd v uv 7.0 8.5 10 v hysteresis v h 0.45 0.65 0.85 v for v r v uvr 3.5 4.1 4.8 v hysteresis v h 0.16 0.3 0.4 v power supply current v dd = 10v i dd - 2.0 2.5 ma v dd = 12v i dd - 3.0 4.0 ma v dd = 18v i dd - 7.0 11.0 ma 7560n-092605-3
7560n-030906-4 s q s r q sensor inputs enable in rc in tachometer out v r _ error amp _ pwm gen. v r /2 frequency to pulse width converter decoder sequence select in reference generator edge triggered delay fault indicator out pwm control in brake in o 1 o 2 o 3 o 6 o 5 o 4 top driver polarity select in top driver outputs bottom driver outputs + _ + + + _ brake select figure 2. LS7560N / ls7561n motor controller block diagram overcurrent sense in 17 16 15 14 13 12 22 23 8 6 7 5 2 27 v r 26 24 19 25 10 11 9 nc for LS7560N v dd for ls7561n 20 21 3 1 r v dd v ss 28 18 internal bond pad + 100mv f/r - v r v r v r v r v r v r v r low v dd detect v dd switch v dd switch v dd v r control control v dd v dd v dd v dd v dd v dd low v r detect error amp (-) error amp (+) error amp out oscillator +v -v 4
figure 5 . in this configuration, the pwm output duty cycle to the motor drivers is directly pro- portional to the dc voltage applied to pin 6, since pins 7 and 8 are tied together. figure 3. the closed loop motor control operation is achieved by ap- plying the tachometer output at pin 5 into the negative terminal of the error amplifier (pin 7) through an r1-c1-r2 integrating network. the r1-c1 network is configured as a feedback circuit around the amplifier. since the tachometer output has a fixed positive pulse width, the average value of the pulse train is directly proportional to the motor speed. the desired speed is selected by applying a voltage at the pos- itive input (pin 6) of the error amplifier. the resultant output voltage of the error amplifier is applied to an internal compar- ator along with a ramp waveform generated by the rc network at pin 9. the pwm signal at the comparator output is used to drive outputs 1 thru 6 and com- plete the closed loop. for this configuration, pin 20, the top driver polarity select must be tied to ground. figure 4 . this three phase half wave motor controller has no top power tran- sistor to disconnect the windings from the power supply when the brake is ap- plied. instead, a switching transistor is used which will permit braking for a time determined by the rc time constant. when the capacitor discharges past the enable input switching point, the outputs will be turned off. ** switch used to connect the error amplifier out and (-) input together when brake select input is low and brake is applied. the speed setting selected by r3 also sets the pwm rate during braking. out6 out5 out4 12 13 14 10 11 v m enable brake 23 2 r c v r figure 4. three-phase half-wave motor controller 19 (+) (-) overcurrent sense v r 7 8 6 19 9 v r osc error amp(-) error amp out error amp(+) r t c t figure 5. open loop controller 7560n-030906-5 24 25 26 27 21 20 22 15 16 17 14 13 12 10 11 5 7 8 6 9 4 3 28 18 19 2 1 23 rotor out1 out2 out3 out4 out5 out6 s1 s2 s3 f/r pwm cntrl top drv pol sel brake sel brake overcurrent sense seq sel tach out enable error amp osc rc v r v ss v dd fault v m v m figure 3. three phase closed loop full wave motor controller c s v r c t r t 10k r2 100k c1 0.1f * * * r1 typical values * 1m * v r s1 s2 s3 (-) out (+) s1 s2 s3 r s (+) (-) r3 * * r f
7560n-080305-6 figure 6 . four phase motor control requires only two hall sensor inputs spaced 90 electrical degrees apart. s1 is connected to one sensor and s2 and s3 are tied together and connected to the other sensor (refer to table 1). the brake input (pin 23) is used to control the top driver select (pin 20) and the top motor drivers. when the brake input is applied, the top motor driv- ers are turned off and the top driver polarity select is forced low turning on the outputs 1 and 3. since outputs 4 and 6 are also turned on, the motor windings become shorted together. the information included herein is believed to be accurate and reliable. however, lsi computer systems, inc. assumes no responsibilities for inaccuracies, nor for any infringements of patent rights of others which may result from its use. 17 15 14 12 10 11 rotor 3 1 2 4 24 25 26 s1 s2 s3 20 v m out1 out3 out4 out6 figure 6. four-phase full-wave motor controller 23 brake top driver polarity select v m s1 s2, s3 overcurrent sense (+) (-) v m s1 s2, s3
figure 7. this four phase half wave motor controller uses the same brake circuit as in figure 4 and switches the top driver select from a high to a low as in figure 6. figure 8. using an analog switch (such as the cd4066) pwm braking can be employed when the brake is applied. at that time, the error amplifier is configured as a voltage follower and its input is switched from the speed adjustment control to the pwm rate control. by adjusting the pwm rate control, the average motor current during braking can be controlled. 11 14 10 17 15 12 v m out1 out3 out4 out6 v r figure 7. four-phase half-wave motor controller 19 2 20 23 enable top driver polarity select brake (+) (-) overcurrent sense 22 23 5 7 6 8 brake select brake tach out out v r v r (-) (+) error amp 1m 100k speed control pwm rate control figure 8. pwm braking 0.1? v r brake brake brake brake brake brake brake brake brake brake typical values * * * * r2 r1 c1 7560n-030906-7
table 1. output commutation sequence for three-phase operation LS7560N sensor electrical separation top bottom 60? 120? drivers drivers s1, s2, s3 s1, s2, s3 f/r en brk ocs o1, o2, o3 o4, o5, o6 fault 0 0 0 0 0 1 1 1 0 0 0 1 1 0 1 0 1 1 0 0 1 0 1 1 1 0 0 1 1 0 0 1 0 1 1 1 0 1 0 0 1 1 0 0 1 1 0 1 0 0 1 1 1 1 1 1 0 1 1 0 0 1 0 1 1 0 0 1 0 1 1 0 1 0 1 1 0 0 1 0 1 0 0 1 1 0 0 1 0 1 1 1 1 0 0 0 1 1 0 0 1 1 0 1 0 0 0 0 x x 0 x 1 1 1 0 0 0 0 1 0 1 1 1 1 x x 0 x 1 1 1 0 0 0 0 0 0 0 0 0 1 0 1 0 0 1 0 1 1 0 0 1 1 0 0 1 0 1 0 1 0 0 1 0 1 0 0 1 1 1 1 0 1 0 0 0 1 0 0 0 1 1 0 0 1 1 1 1 1 1 1 0 0 1 0 0 0 1 1 0 1 0 1 0 1 1 0 1 0 0 1 0 0 1 1 0 0 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 1 0 0 1 0 1 0 0 0 0 x x 0 x 1 1 1 0 0 0 0 1 0 1 1 1 1 x x 0 x 1 1 1 0 0 0 0 x x x x x x x x 1 x 1 1 1 1 1 1 1 x x x x x x x x 0 1 1 1 1 0 0 0 0 x x x x x x x 0 0 x 1 1 1 0 0 0 0 note 1 : this table assumes the top driver polarity select (pin 20) = logic 0. for pin 20 = logic 1, invert the polarity of the top drivers. note 2 : for the ls7561n, the overcurrent sense = logic 1 only forces the bottom drivers to a logic 0. it has no effect on the top driver outputs which are determined by the other inputs as shown in the table. en = enable brk = brake ocs = over current sense table 2. output commutation sequence for four-phase operation LS7560N sensor electrical separation = 90? top bottom drivers drivers s1 s2, s3 f/r en brk ocs o1, o3 o4, o6 fault 0 0 1 1 0 0 1 0 0 0 1 1 0 1 1 0 0 0 1 0 0 1 1 1 1 1 0 0 0 0 1 0 1 0 1 1 1 0 0 0 0 0 1 1 0 0 0 1 0 0 0 0 1 0 1 1 0 0 1 0 0 0 0 0 1 1 1 1 0 1 0 0 1 0 0 0 1 0 1 0 1 0 0 0 1 0 0 1 x x x x 1 x 0 0 1 1 1 x x x x 0 1 0 0 0 0 0 x x x 0 0 x 0 0 0 0 0 note 1 : sequence input (pin 1) set at a logic 1. note 2 : this table assumes the top driver polarity select (pin 20) = logic 1. for pin 20 = logic 0, invert the polarity of the top drivers. note 3 : for the ls7561n, the overcurrent sense = logic 1 only forces the bottom drivers to a logic 0. it has no effect on the top driver outputs which are determined by the other inputs as shown on the table. en = enable brk = brake ocs = over current sense 7560n-030906-8
|
