LV8727 Bi-CMOS LSI PWM Constant-Current Control Stepper Motor Driver Application Note http://onsemi.com Overview The LV8727 is a micro-step stepper motor driver for bipolar stepper motors controlled by PWM. This LV8727 supports eight micro step resolutions of Half, 1/8, 1/16, 1/32, 1/64, 1/128, 1/10 and 1/20, which is driven simply by step input. Function • Single-channel PWM current control stepper motor driver. • BiCDMOS process IC. • Output on-resistance (upper side: 0.25Ω; lower side: 0.15Ω; total of upper and lower: 0.4Ω; Ta = 25˚C, IO = 4.0A) • Half, 1/8, 1/16, 1/32, 1/64, 1/128, 1/10, 1/20 Step are selectable. • Advance the excitation step with the only step signal input. • Available forward reverse control • Over current protection circuit • Thermal shutdown circuit • Input pull down resistance. • With reset pin and enable pin. Typical Applications • Large format Printer • Stage Lighting Semiconductor Components Industries, LLC, 2013 December, 2013 1/43 LV8727 Application Note Pin Assignment Package Dimensions unit : mm (typ) 3236A 2/43 LV8727 Application Note Block Diagram Output pre stage Output pre stage Output pre stage Output pre stage 3/43 LV8727 Application Note Specifications Absolute Maximum Ratings at Ta = 25˚C Parameter Symbol Supply voltage VM max Output current IO max Output peak current IO peak Logic input voltage Conditions Ratings Unit tw≤10ms, duty 20% 50 V 4 A 4.6 A VIN max 6 V MO/DOWN input voltage MO max/DOWN max 6 V VREF input voltage VREF max 6 V Allowable power dissipation Pd max 2.45 W Operating temperature Topr -30 to +85 ˚C Storage temperature Tstg -55 to +150 ˚C Indipendent IC Caution 1) Absolute maximum ratings represent the value which cannot be exceeded for any length of time. Caution 2) Even when the device is used within the range of absolute maximum ratings, as a result of continuous usage under high temperature, high current, high voltage, or drastic temperature change, the reliability of the IC may be degraded. Please contact us for the further details. Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. Recommended Operating Conditions at Ta = 25°C Parameter Symbol Conditions Ratings min typ Unit max Supply voltage range VM 9 45 V Logic input voltage VIN 0 5 V VREF input voltage range VREF 0 3 V Electrical Characteristics at Ta = 25˚C, VM = 24V, VREF = 1.5V Parameter Symbol Conditions min Typ max Unit Standby mode current drain IMstn ST="L" 70 100 µA current drain IM ST="H", ENABLE="H", no load 3.5 4.9 mA 180 210 ˚C Thermal shutdown temperature TSD Design guarantee Thermal hysteresis width ∆TSD Design guarantee Logic pin input current IINL VIN=0.8V IINH VIN=5V Logic input high-level voltage VINH Logic input low-level voltage VINL FDT pin high-level voltage Vfdth 3.5 FDT pin middle-level voltage Vfdtm 1.1 FDT pin low-level voltage Vfdtl Chopping frequency Fch 150 40 ˚C 3 8 15 µA 30 50 70 µA 0.8 V 3.1 V 2.0 COSC1=100pF V V 70 100 0.8 V 130 kHz OSC1 pin charge / discharge current IOSC1 7 10 13 µA Chopping oscillator circuit Vtup1 0.8 1 1.2 V threshold voltage Vtdown1 0.3 0.5 0.7 V VREF pin input voltage Iref VREF=1.5V DOWN output residual voltage VolDO Idown=1mA 50 200 mV MO pin residual voltage VolMO Imo=1mA 50 200 mV Hold current switching frequency Fdo COSC2=1500pF 1.12 1.6 2.08 Hz OSC2 pin charge / discharge current IOSC2 7 10 13 µA 0.8 1 1.2 V Hold current switching frequency threshold Vtup2 -0.5 µA voltage Vtdown2 0.5 0.7 V Output on-resistance Ronu IO=4.0A, high-side ON resistance 0.25 0.325 Ω Rond IO=4.0A, low-side ON resistance 0.15 0.195 Ω Output leakage current Ioleak VM=50V 50 µA Diode forward voltage VD ID=-4.0A 1 1.3 V Current setting reference voltage VRF VREF=1.5V, Current ratio 100% 0.5 0.515 V 0.3 0.485 4/43 LV8727 Application Note 250 150 IM (µA) IMstn (µ A) 200 100 50 0 0 10 20 30 40 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 0 50 10 60 2 50 1.8 50 1.6 VIN (V) Iin (µA) 40 Figure 2 Current Drain vs. VM Voltage 40 30 20 1.4 1.2 1 0.8 10 0.6 0 0 2 4 0 6 10 20 30 40 50 VM (V) Vin (V) Figure 4. ST pin Threshold Voltage vs. VM Voltage Figure 3 Logic pin input Current vs. Logic input Voltage 2 60 1.8 50 1.6 40 IREF (nA) 1.4 1.2 1 VINH 0.8 VINL 0.6 0 10 20 30 30 20 10 0 40 0 1 2 VM (V) Figure 6. VREF pin input Current vs. VREF Voltage 50 40 40 30 30 Vsatemo (mV) 50 20 10 0 0 0.2 0.4 0.6 Imon (mA) 0.8 1 Figure 7 MO pin saturation voltage vs. MO pin input current 3 VREF (V) Figure 5. Logic High/Low-level input Voltage vs. VM Voltage Vsatmon (mV) 30 VM (V) VM (V) Figure 1 Stanby Mode Current Drain vs. VM Voltage VIN (V) 20 20 10 0 0 0.2 0.4 0.6 0.8 1 Iemo (mA) Figure 8 DOWN pin saturation voltage vs. DOWN pin input current 5/43 LV8727 Application Note 0.3 0.4 0.3 0.1 Ron (Ω) Ron (Ω) 0.2 Ronu 0.1 Rond 0 0 1 2 3 4 Ronu Rond 0 5 -50 0 50 100 150 TEMPERATURE (˚C) Iout (A) Figure 9 Output on Resistance vs. Output Current VF (V) 0.2 1.1 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Figure 10. Output on Resistance vs. Temperature VFu VFd 0 1 2 3 4 5 Iout (A) Figure 11 Diode forward voltage vs. Output Current 6/43 LV8727 Application Note Pin Functions Pin No. Pin Name Pin Function 7 MD1 Excitation mode switching pin 8 MD2 Excitation mode switching pin 9 MD3 Excitation mode switching pin 10 OE Output enable signal input pin 11 RST Reset signal input pin 12 FR Forward / Reverse signal input pin 13 STEP Step clock pulse signal input pin Equivalent Circuit Regulator1 10kΩ 100kΩ GND 6 ST Chip enable pin. Channel 1 OUTB output pin. 1 OUT1B 2 RF1 3 PGND1 Channel 1 Power system ground 4 OUT1A Channel 1 OUTA output pin. 5 VM1 21 VM2 22 OUT2B Channel 2 OUTB output pin. 23 PGND2 Channel 2 Power system ground 24 RF2 Channel 2 current-sense resistor 25 OUT2A Channel 1 current-sense resistor connection pin. Channel 1 motor power supply connection pin. Channel 2 motor power supply connection pin. connection pin. Channel 2 OUTA output pin. Continued on next page. 7/43 LV8727 Application Note Continued from preceding page. Pin No. 19 Pin Name VREF Pin Function Equivalent Circuit Constant-current control reference voltage input pin. Regulator1 500Ω 500Ω GND 17 DOWN Holding current output pin. 18 MO Position detecting monitor pin. 14 OSC1 Copping frequency setting capacitor 15 OSC2 connection pin. STEP input detection time setting capacitor connection pin. Continued on next page. 8/43 LV8727 Application Note Continued from preceding page. Pin No. 16 Pin Name FDT Pin Function Equivalent Circuit Constant-current control reference voltage input pin. 9/43 LV8727 Application Note Reference describing operation (1) Stand-by function When ST pin is at low levels, the IC enters stand-by mode, where all the logics are reset and the outputs are turned OFF. When ST pin is at high levels, the stand-by mode is released. (2) STEP pin function STEP input advances electrical angle at every rising edge (advances step by step) . Input ST Low STEP * Operating mode Standby mode High Excitation step proceeds High Excitation step is kept STEP input MIN pulse width (common in H/L): 500ns (MAX input frequency: 1MHz) However, constant current control is performed by PWM during chopping period, which is set by the capacitor connected between OSC1 and GND. You need to perform chopping more than once per step. For this reason, for the actual STEP frequency, you need to take chopping frequency and chopping count into consideration. For example, if chopping frequency is 50kHz (20μs) and chopping is performed twice per step, the maximum STEP frequency is obtained as follows: f＝1/(20μs×2) = 25kHz. (3) Input timing Figure 12. Input timing chart TstepH/TstepL : Clock H/L pulse width (min 500ns) Tds : Data set-up time (min 500ns) Tdh : Data hold time (min 500ns) 10/43 LV8727 Application Note (4) Excitation setting method Set the micro step resolution setting as shown in the following table by setting MD1 pin, MD2 pin and MD3 pin. Input MD3 MD2 MD1 Micro step resolution Excitation mode Initial position 1ch current 2ch current Low Low Low Half Step 1-2 phase 100% 0% Low Low High 1/8 Step 2W1-2 phase 100% 0% Low High Low 1/16 Step 4W1-2 phase 100% 0% Low High High 1/32 Step 8W1-2 phase 100% 0% High Low Low 1/64 Step 16W1-2 phase 100% 0% High Low High 1/128 Step 32W1-2 phase 100% 0% High High Low 1/10 Step - 100% 0% High High High 1/20 Step - 100% 0% The initial position is also the default state at start-up and excitation position at counter-reset in each Micro step resolution. (5) Position detection monitoring function The MO position detection monitoring pin is the open drain type. When the excitation position is in the initial position, the MO output is placed in the ON state. (Refer to "Examples of current waveforms in each of the excitation modes.") (6) Output current setting Output current is set shown below by the VREF pin (applied voltage) and a resistance value between RF1 (2) pin and GND. IOUT = (VREF / 3) / RF1 (2) resistance * The setting value above is a 100% output current in each micro step resolution. (Example) When VREF = 0.9V and RF1 (2) resistance is 0.1Ω, the setting is shown below. IOUT = (0.9V / 3) / 0.1Ω = 3.0A If VREF is open or the setting is out of the recommendation operating range, output current will increase and you cannot set constant current under normal condition. Hence, make sure that VREF is set in accordance with the specification. 11/43 LV8727 Application Note (7) Output enable function When the OE pin is set Low, the output is forced OFF and goes to high impedance. However, the internal logic circuits are operating, so the excitation position proceeds when the STEP is input. Therefore, when OE pin is returned to High, the output level conforms to the excitation position proceeded by the STP input. OE High Low Operating mode Output ON Output OFF Figure 13. Output enable function timing chart (8) Reset function When the RST pin is set Low, the output goes to initial mode and excitation position is fixed in the initial position for STEP pin and FR pin input. MO pin outputs at low levels at the initial position. (Open drain connection) RST High Low Operating mode Normal operation Reset state Figure 14. Reset function timing chart 12/43 LV8727 Application Note (9) Forward / reverse switching function FR Operating mode Low Clockwise (CW) High Counter-clockwise (CCW) FR CW mode CCW mode CW mode STEP Excitation position (1) (2) (3) (4) (5) (6) (5) (4) (3) (4) (5) 1ch output 2ch output Figure 15. Forward/Reverse switching function timing chart The internal D/A converter proceeds by a bit on the rising edge of the step signal input to the STP pin. In addition, CW and CCW mode are switched by FR pin setting. In CW mode, the channel 2 current phase is delayed by 90° relative to the channel 1 current. In CCW mode, the channel 2 current phase is advanced by 90° relative to the channel 1 current. (10)Chopping frequency setting function Chopping frequency is set as shown below by a capacitor between OSC1 pin and GND. Fcp = 1 / (Cosc1 / 10 х 10-6) (Hz) (Example) When Cosc1 = 180pF, the chopping frequency is shown below. Fcp = 1 / (180 х 10-12 / 10 х 10-6) = 55.5(kHz) The higher the chopping frequency is, the greater the output switching loss becomes. As a result, heat generation issue arises. The lower the chopping frequency is, the lesser the heat generation becomes. However, current ripple occurs. Since noise increases when switching of chopping takes place, you need to adjust frequency with the influence to the other devices into consideration. The frequency range should be between 40kHz and 125kHz. 13/43 LV8727 Application Note (11)DOWN ouput pin The DOWN output pin is open-drain output. The pin turns on and outputs Low level when STEP signal is not input for over the detection time. The open-drain output that has been turned-on is turned off by the next STEP signal. The detection time of STEP signal (Tdown) is set as shown below by a capacitor between OSC2 pin and GND. Tdown = Cosc2 х 0.4 х 109 (s) (Example) When Cosc2 = 1500pF, the holding current switching time is as shown below. Tdown = 1500pF х 0.4 х 109 = 0.6 (s) Figure 16. DOWN output function timing chart By connecting external parts as shown in the example below using DOWN output pin, STEP signal is not input for over the detection time. In other words, while the position of the stepper motor is held with conduction, by turning on the DOWN output and lowering the VREF input voltage, the setting current lowers and power consumption is reduced. V1 R1 VREF DOWN R3 R2 Figure 17. Example of DOWN Circuit (Example) When V1=5V, R=27kΩ, R2=4.7kΩ, and R3=1kΩ, the setting is as shown below. DOWN output OFF: VREF = V1 x R2 / (R1+R2) = 0.741V DOWN output ON: VREF = V1 x (R2//R3) / (R1+ (R2//R3)) = 0.126V 14/43 LV8727 Application Note (12)DECAY mode setting Current DECAY method is selectable as shown below by applied voltage to the FDT pin. FDT voltage DECAY method 3.5V ≤ FDT ≤ 5.5V SLOW DECAY 3.1V < FDT < 3.5V Inhibited zone 1.1V ≤ FDT ≤ 3.1V or OPEN MIXED DECAY 0.8V < FDT < 1.1V Inhibited zone 0V ≤ FDT ≤ 0.8V FAST DECAY For the inhibited zone, either above or below DECAY method is selected. Ex) For the Inhibited zone where FDT voltage is 3.1V < FDT <3.5V, either SLOW DECAY or MIXED DECAY is selected. Since each threshold voltage does not have hysteresis, it is not recommended to change DECAY method during motor operation. 15/43 LV8727 Application Note (13)Output current vector locus (one step is normalized to 90 degrees) Half, 1/8, 1/16, 1/32, 1/64, 1/128 Step 100.0 θ0 θ8 θ16 θ24 θ32 θ40 θ48 1ch current ratio (%) θ56 θ64 66.7 θ72 θ80 θ88 θ96 33.3 θ104 θ112 θ120 θ128 0.0 0.0 33.3 66.7 100.0 2ch current ratio (%) Figure 18. Output current vector Current setting ratio in each micro step resolution STEP θ0 θ1 θ2 θ3 θ4 θ5 θ6 θ7 θ8 θ9 θ10 θ11 θ12 θ13 θ14 θ15 θ16 θ17 θ18 θ19 θ20 θ21 θ22 θ23 θ24 θ25 1/128 (%) 1ch 100 100 100 100 100 100 100 100 100 99 99 99 99 99 99 98 98 98 98 97 97 97 96 96 96 95 1/64 (%) 2ch 0 1 2 4 5 6 7 9 10 11 12 13 15 16 17 18 20 21 22 23 24 25 27 28 29 30 1/32 (%) 1ch 100 2ch 0 100 2 100 5 100 7 100 10 99 12 99 15 99 17 98 20 98 22 97 24 96 27 96 29 1/16 (%) 1ch 100 2ch 0 100 5 100 10 99 15 98 20 97 24 96 29 1/8 (%) 1ch 100 2ch 0 100 10 98 20 96 29 Half (%) 1ch 100 2ch 0 98 20 1ch 100 2ch 0 Continued on next page. 16/43 LV8727 Application Note Continued from preceding page. STEP θ26 θ27 θ28 θ29 θ30 θ31 θ32 θ33 θ34 θ35 θ36 θ37 θ38 θ39 θ40 θ41 θ42 θ43 θ44 θ45 θ46 θ47 θ48 θ49 θ50 θ51 θ52 θ53 θ54 θ55 θ56 θ57 θ58 θ59 θ60 θ61 θ62 θ63 θ64 θ65 θ66 θ67 θ68 θ69 θ70 θ71 θ72 θ73 θ74 θ75 θ76 θ77 θ78 θ79 θ80 θ81 θ82 θ83 θ84 θ85 θ86 θ87 θ88 θ89 θ90 1/128 (%) 1ch 95 95 94 94 93 93 92 92 91 91 90 90 89 89 88 88 87 86 86 85 84 84 83 82 82 81 80 80 79 78 77 77 76 75 74 73 72 72 71 70 69 68 67 66 65 64 63 62 62 61 60 59 58 57 56 55 53 52 51 50 49 48 47 46 45 1/64 (%) 2ch 31 33 34 35 36 37 38 39 41 42 43 44 45 46 47 48 49 50 51 52 53 55 56 57 58 59 60 61 62 62 63 64 65 66 67 68 69 70 71 72 72 73 74 75 76 77 77 78 79 80 80 81 82 82 83 84 84 85 86 86 87 88 88 89 89 1/32 (%) 1/16 (%) 1ch 95 2ch 31 1ch 2ch 94 34 94 34 93 36 92 38 92 38 91 41 90 43 90 43 89 45 88 47 88 47 87 49 86 51 86 51 84 53 83 56 83 56 82 58 80 60 80 60 79 62 77 63 77 63 76 65 74 67 74 67 72 69 71 71 71 71 69 72 67 74 67 74 65 76 63 77 63 77 62 79 60 80 60 80 58 82 56 83 56 83 53 84 51 86 51 86 49 87 47 88 47 88 45 89 1/8 (%) Half (%) 1ch 2ch 1ch 2ch 92 38 92 38 88 47 83 56 83 56 77 63 71 71 71 71 63 77 56 83 56 83 47 88 1ch 2ch 71 71 Continued on next page. 17/43 LV8727 Application Note Continued from preceding page. STEP θ91 θ92 θ93 θ94 θ95 θ96 θ97 θ98 θ99 θ100 θ101 θ102 θ103 θ104 θ105 θ106 θ107 θ108 θ109 θ110 θ111 θ112 θ113 θ114 θ115 θ116 θ117 θ118 θ119 θ120 θ121 θ122 θ123 θ124 θ125 θ126 θ127 θ128 1/128 (%) 1ch 44 43 42 41 39 38 37 36 35 34 33 31 30 29 28 27 25 24 23 22 21 20 18 17 16 15 13 12 11 10 9 7 6 5 4 2 1 0 2ch 90 90 91 91 92 92 93 93 94 94 95 95 95 96 96 96 97 97 97 98 98 98 98 99 99 99 99 99 99 100 100 100 100 100 100 100 100 100 1/64 (%) 1/32 (%) 1/16 (%) 1ch 2ch 1ch 2ch 43 90 43 90 41 91 38 92 38 92 36 93 34 94 34 94 31 95 29 96 29 96 27 96 24 97 24 97 22 98 20 98 20 98 17 99 15 99 15 99 12 99 10 100 10 100 7 100 5 100 5 100 2 100 0 100 0 100 1/8 (%) Half (%) 1ch 2ch 1ch 2ch 38 92 38 92 29 96 20 98 20 98 10 100 0 100 0 100 1ch 2ch 0 100 18/43 LV8727 Application Note Output current vector locus (one step is normalized to 90 degrees) 1/10, 1/20 Step 100.0 θ0 θ1 θ2 θ3 θ4 θ5 θ6 θ7 θ8 1ch current ratio (%) θ9 θ10 66.7 θ11 θ12 θ13 θ14 θ15 33.3 θ16 θ17 θ18 θ19 θ20 0.0 0.0 33.3 66.7 100.0 2ch current ratio (%) Figure 19. Output current vector Current setting ratio in each micro step resolution 1/20 (%) STEP θ0 θ1 θ2 θ3 θ4 θ5 θ6 θ7 θ8 θ9 θ10 θ11 θ12 θ13 θ14 θ15 θ16 θ17 θ18 θ19 θ20 1ch 100 100 99 97 95 92 89 85 81 76 71 65 59 52 45 38 31 23 16 8 0 1/10 (%) 2ch 0 8 16 23 31 38 45 52 59 65 71 76 81 85 89 92 95 97 99 100 100 1ch 100 2ch 0 99 16 95 31 89 45 81 59 71 71 59 81 45 89 31 95 16 99 0 100 19/43 LV8727 Application Note (14)Current wave example in each micro step resolution. Half Step (CW) STEP MO (%) 100 I1 0 －100 (%) 100 I2 0 －100 1/8 Step (CW) STEP MO [%] 100 50 I1 0 -50 -100 [%] 100 50 I2 0 -50 -100 20/43 LV8727 Application Note 1/16 Step Mode (CW) 1/32 Step Mode (CW) STEP MO [%] 100 50 I1 0 -50 -100 [%] 100 50 0 I2 -50 -100 21/43 LV8727 Application Note 1/64 Step Mode (CW) STEP MO [%] 100 50 I1 0 -50 -100 [%] 100 50 I2 0 -50 -100 1/128 Step Mode (CW) 22/43 LV8727 Application Note 1/10 Step Mode (CW) 1/20 Step Mode (CW) 23/43 LV8727 Application Note (15)Current control operation SLOW DECAY current control operation When FDT pin voltage is over 3.5 V, the constant-current control is operated in SLOW DECAY mode. (Sine-wave increasing direction) STEP Set tin g curre nt S etting cu rren t Coil curre nt ch opp ing period B la nking Tim e Current mod e CHA RG E SLOW CH ARGE SLOW (Sine-wave decreasing direction) S TE P S e ttin g c u r r e nt Co il c urre nt S e tt in g c u rr e n t B l a nk in g T im e fch op C u r re n t m od e C H A RG E SL OW B la n k in g Ti m e SL OW B la n kin g T im e SL OW Figure 20. Constant current control timing chart Each of current modes operates with the follow sequence. The IC enters CHARGE mode at a rising edge of the chopping oscillation. (A period of CHARGE mode (Blanking Time) is forcibly preset to approximately 1 µs, regardless of the current value of the coil current (ICOIL) and set current (IREF)). After the period of the blanking time, the IC operates in CHARGE mode until ICOIL ≥ IREF. After that, the mode switches to the SLOW DECAY mode and the coil current is attenuated until the end of a chopping period. At the constant-current control in SLOW DECAY mode, it takes time to follow up the setting current from the coil current (or may not be followed) for the current delay attenuation. 24/43 LV8727 Application Note Slow DECAY output transistor operation mode 1. CHARGE 2. VM VM Current pathway ON OFF OFF U1 U2 OUTA OFF U1 OUTB U2 OUTB OUTA OFF OFF ON L1 L2 ON L1 L2 RF RF Charge increases current. Switch from Charge to Slow Decay 3. SLOW 4. VM VM OFF OFF U1 U2 OUTA OFF U2 OUTA OUTB ON L1 OUTB OFF ON L2 ON L1 L2 RF RF Current regeneration Slow Decay OFF U1 by Switch from Slow Decay to Charge Figure 21. SLOW DECAY output transistor operation sequence This IC controls constant current by performing chopping to output transistor. As shown above, by repeating the process from 1 to 4, setting current is maintained. Chopping consists of 2 modes: Charge/ Slow decay. In SLOW DECAY mode, for switching mode (No.2, 4), there are “off period” in upper and lower transistor to prevent crossover current between the transistors. This off period is set to be constant (≈ 0.375μs) which is controlled by the internal logic. The diagrams show parasitic diode generated due to structure of MOS transistor. When the transistor is off, output current is regenerated through this parasitic diode. Output Transistor Operation Function OUTA→OUTB (CHARGE) Output Tr U1 U2 L1 L2 OUTB→OUTA (CHARGE) Output Tr U1 U2 L1 L2 CHARGE ON OFF OFF ON SLOW OFF OFF ON ON CHARGE OFF ON ON OFF SLOW OFF OFF ON ON 25/43 LV8727 Application Note 5ms/div STEP 5V/div VM=24V VREF=0.3V FDT=5V RF=0.1Ω CHOP=180pF Motor Current 0.5A/div OSC1 0.5V/div Figure 22.Constant current control waveform 20μs/div STEP 5V/div 20μs/div STEP 5V/div Motor Current 200mA/div Motor Current 200mA/div Set Current Set Current OCS1 0.5V/div OCS1 0.5V/div Figure 24. Sine wave decreasing direction Figure 23. Sine wave increasing direction 5μs/div Motor Current 100mA/div OSC1 0.5V/div CHARGE SLOW Figure 25. Constant current control waveform (Stationary state) When the current reaches to the setting current, it is switched to Slow Decay mode which continues over the Discharge period of triangle wave. 26/43 LV8727 Application Note FAST DECAY current control operation When FDT pin voltage is a voltage under 0.8V, the constant-current control is operated in FAST DECAY mode. (Sine-wave increasing direction) STEP Setti ng current Setti ng current Coil current B lanking Tim e fchop Current mode CH ARGE FAST CH ARGE FAST (Sine-wave decreasing direction) S TE P S e ttin g c u r r e nt Co il c urre nt S et tin g c u r r en t B l a nk in g T im e fch op C ur ren t mo de C H A RG E FA S T B la n k in g Ti m e FA S T CH A RG E FA S T Figure 26. Constant current control timing chart Each of current modes operates with the following sequence. The IC enters CHARGE mode at a rising edge of the chopping oscillation. (A period of CHARGE mode (Blanking Time) is forcibly preset to approximately 1 µs, regardless of the current value of the coil current (ICOIL) and set current (IREF)). After the period of the blanking time, the IC operates under CHARGE mode until ICOIL ≥ IREF. After that, the mode switches to the FAST DECAY mode and the coil current is attenuated until the end of a chopping period. At the constant-current control in FAST DECAY mode, it does not take long to follow the setting current from the coil current for the current fast attenuation. However, the current ripple value may be higher. 27/43 LV8727 Application Note FAST DECAY output transistor operation mode Charge increases current. Switch from Charge to Fast Decay 3. FAST 4. VM VM OFF ON OFF U2 U1 OUTA U2 OUTB ON OUTA OUTB OFF OFF L1 OFF U1 L2 OFF L1 RF L2 RF Switch from Fast Decay to Charge Current regeneration by Fast Decay Figure 27. FAST DECAY output transistor operation sequence This IC controls constant current by performing chopping to output transistor. As shown above, by repeating the process from 1 to 4, setting current is maintained. Chopping consists of 2 modes: Charge/ Fast decay. In FAST DECAY mode, for switching mode (No.2, 4), there are “off period” in upper and lower transistor to prevent crossover current between the transistors. This off period is set to be constant (≈ 0.375μs) which is controlled by the internal logic. The diagrams show parasitic diode generated due to structure of MOS transistor. When the transistor is off, output current is regenerated through this parasitic diode. Output Transistor Operation Function OUTA→OUTB (CHARGE) Output Tr U1 U2 L1 L2 OUTB→OUTA (CHARGE) Output Tr U1 U2 L1 L2 CHARGE ON OFF OFF ON FAST OFF ON ON OFF CHARGE OFF ON ON OFF FAST ON OFF OFF ON 28/43 LV8727 Application Note 5ms/div STEP 5V/div VM=24V VREF=0.3V FDT=5V RF=0.1Ω CHOP=180pF Motor Current 0.5A/div OSC1 0.5V/div Figure 28.Constant current control waveform 20μs/div STEP 5V/div 20μs/div Motor Current 200mA/div Set Current STEP 5V/div Set Current Motor Current 200mA/div OCS1 0.5V/div OCS1 0.5V/div Figure 30. Sine wave decreasing direction Figure 29. Sine wave increasing direction 5μs/div Motor Current 100mA/div OSC1 0.5V/div CHARGE FAST Figure 31. Constant current control waveform (Stationary state) When the current reaches to the setting current, it is switched to Fast Decay mode which continues over the Discharge period of triangle wave. 29/43 LV8727 Application Note MIXED DECAY current control operation When FDT pin voltage is a voltage between 1.1 V to 3.1 V or OPEN, the constant-current control is operated in MIXED DECAY mode. (Sine-wave increasing direction) STEP Setti ng curren t Setti ng current Coil current B lanking Tim e fchop C urrent m ode C HARGE SLOW FAST CHARGE SLOW FAS T (Sine-wave decreasing direction) S T EP S e ttin g c ur r e nt Co il c urr en t S e tti ng c u rr e n t B la nk in g T im e fc hop C u rr e n t m o d e C HAR GE S LO W FA S T B la nk in g T im e FAST C H A RG E SL OW Figure 32. Constant current control timing chart Each of current modes operates according to the following sequence. • The IC enters CHARGE mode at a rising edge of the chopping oscillation. ( A period of CHARGE mode (Blanking Time) is forcibly preset to approximately 1μs, regardless of the current value of the coil current (ICOIL) and set current (IREF)). • In a period of Blanking Time, the coil current (ICOIL) and the setting current (IREF) are compared. If an ICOIL < IREF state exists during the charge period: The IC operates in CHARGE mode until ICOIL ≥ IREF. After that, it switches to SLOW DECAY mode and then switches to FAST DECAY mode in the last approximately 1μs of the period. If no ICOIL < IREF state exists during the charge period: The IC switches to FAST DECAY mode and the coil current is attenuated with the FAST DECAY operation until the end of a chopping period. The above operation is repeated. Normally, in the sine wave when current is in increase, the IC operates in SLOW (+ FAST) DECAY mode, and when current is in decrease, the IC operates in FAST DECAY mode until the current is attenuated and reaches the set value and the IC operates in SLOW (+ FAST) DECAY mode. 30/43 LV8727 Application Note (16)Output transistor operation mode Charge increases current. Switch from Charge to Slow Decay Current regeneration by Slow Decay 4. 5. FAST 6. VM VM VM OFF OFF U1 OFF U2 ON ON L1 RF OUTB OFF L2 OFF L1 RF Switch from Slow Decay to Fast Decay U2 OUTA OFF L1 L2 OFF U1 OUTB OUTA OFF OFF U2 OUTB OUTA ON U1 L2 RF Switch from Fast Decay to Charge Current regeneration by Fast Decay Figure 33. Output transistor operation sequence This IC controls constant current by performing chopping to output transistor. As shown above, by repeating the process from 1 to 6, setting current is maintained. Chopping consists of 3 modes: Charge/ Slow decay/ Fast decay. In this IC, for switching mode (No.2, 4, 6), there are “off period” in upper and lower transistor to prevent crossover current between the transistors. This off period is set to be constant (≈ 0.375μs) which is controlled by the internal logic. The diagrams show parasitic diode generated due to structure of MOS transistor. When the transistor is off, output current is regenerated through this parasitic diode. Output Transistor Operation Function OUTA→OUTB (CHARGE) Output Tr U1 U2 L1 L2 OUTB→OUTA (CHARGE) Output Tr U1 U2 L1 L2 CHARGE ON OFF OFF ON SLOW OFF OFF ON ON FAST OFF ON ON OFF CHARGE OFF ON ON OFF SLOW OFF OFF ON ON FAST ON OFF OFF ON 31/43 LV8727 Application Note 5ms/div STEP 5V/div VM=24V VREF=0.3V FDT=5V RF=0.1Ω CHOP=180pF Motor Current 0.5A/div OSC1 0.5V/div Figure 34.Constant current control waveform 20μs/div STEP 5V/div 20μs/div Motor Current 200mA/div Set Current STEP 5V/div Set Current Motor Current 200mA/div OCS1 0.5V/div OCS1 0.5V/div Figure 36. Sine wave decreasing direction Figure 35. Sine wave increasing direction 5μs/div Motor Current 100mA/div OSC1 0.5V/div FAST CHARGE SLOW Figure 37. Constant current control waveform (Stationary state) Motor current switches to Fast Decay mode when triangle wave (CHOP) switches from Discharge to Charge. Approximately after 1μs, the motor current switches to Charge mode. When the current reaches to the setting current, it is switched to Slow Decay mode which continues over the Discharge period of triangle wave. 32/43 LV8727 Application Note (17)Blanking period If, when performing PWM constant-current chopping control over the motor current, the mode is switched from decay to charge, the recovery current of the parasitic diode may flow to the current sensing resistor, which causes noise as well as error detection. To prevent error detection, a blanking period is provided to prevent the noise during mode switching. During this period, the mode is not switched from charge to decay even if noise is carried on the current sensing resistance pin. It is approximately 1µs in the blanking time for this IC. 5us/div 1µs OUT1A 5V/div CHOP 0.5V/div Figure 38. Blanking time waveform (18)Micro step mode switching operation When Micro step mode is switched while the motor is rotating, each drive mode operates with the following sequence. If you switch Microstep mode while the motor is driving, the mode setting will be reflected from the next STEP and the motor advances to the position shown in the following. 1. Microstep (1/128-, 1/64-, 1/32-, 1/16-, 1/8-, Half-step) →Microstep (1/128-, 1/64-, 1/32-, 1/16-, 1/8-, Half-step), Microstep (1/20-, 1/10-step) →Microstep (1/20-, 1/10-step) When a microstep switches to the next microstep, the excitation position is switched to the next corresponding step angle of the next microstep mode. e.g.) When the rotation direction is forward at 1/8-step, and if you switch to 1/128-step (θ16 - θ47), the step angle is set to θ48 at the next step. When the rotation direction is forward at 1/128 step, and if you switch to 1/8-step (θ48), the step angle is set to θ49 at the next step. 2. Microstep (1/128-, 1/64-, 1/32-, 1/16-, 1/8-, Half-step) →Microstep (1/20-, 1/10-step), Microstep (1/20-, 1/10-step) →Microstep (1/128-, 1/64-, 1/32-, 1/16-, 1/8-, Half-step) When a microstep is switched to the next, the excitation position is switched to the any step angle of the next microstep mode. Therefore, swiching should be performed when the excitation position comes to the initial position. (Please refer to the step angle on pp.16-19 for the description on “θ*”.) 33/43 LV8727 Application Note Micro step mode switching operation Microstep (1/128-, 1/64-, 1/32-, 1/16-, 1/8-, Half-step) →Microstep (1/128-, 1/64-, 1/32-, 1/16-, 1/8-, Half-step), VM=24V, VDD=5V VREF=0.45V, RNF=0.1Ω PS=High, OE=High, RST=High, fSTEP=600Hz 5ms/div 5ms/div MD1 5V/div MD1 5V/div MO 5V/div MO 5V/div Iout1 1A/div Iout1 1A/div Iout2 1A/div Iout2 1A/div Figure39. Micro step (Half-step) → Micro step (1/8-step) MD2=Low, MD3=Low Figure40. Micro step (1/8-step) → Micro step (Half-step) MD2=Low, MD3=Low Microstep (1/20-, 1/10-step) →Microstep (1/20-, 1/10-step) VM=24V, VDD=5V VREF=0.45V, RNF=0.1Ω PS=High, OE=High, RST=High, fSTEP=1200Hz 5ms/div Figure.41 Micro step (1/10-step) → Micro step (1/20-step) MD2=High, MD3=High 5ms/div MD1 5V/div MD1 5V/div MO 5V/div MO 5V/div Iout1 1A/div Iout1 1A/div Iout2 1A/div Iout2 1A/div Figure42. Micro step (1/20tep) → Micro step (1/10-step) MD2=High, MD3=High 34/43 LV8727 Application Note Output short-circuit protection function (1) Output short-circuit detection operation VM short Tr1 Tr1 Tr3 ON OUTA 1.High current flows if Tr3 and Tr4 are ON. 2.If RF voltage> setting voltage, then the mode switches to SLOW decay. 3.If the voltage between drain and source of Tr4 exceeds the reference voltage for 2μs, short status is detected. VM VM OFF OUTA OFF OUTB M Tr2 OFF Tr3 Tr4 Tr2 ON ON OFF OUTB M Tr4 ON RF RF Short-circuit Detection GND short VM Short-circuit Detection Short-circuit Detection Tr1 Tr3 ON OUTA M OFF OUTB Tr2 OFF VM Tr1 ON OUTA Tr4 Tr2 ON OFF Tr3 M OFF OUTB Tr4 ON RF RF Load short VM Tr1 ON OUTA Short-circuit Detection Tr3 M Tr2 OFF RF OFF OUTB VM Tr1 ON OUTA Tr4 Tr2 ON OFF Tr3 M OFF OUTB Tr4 ON RF (left schematic) 1.High current flows if Tr3 and Tr4 are ON 2. If the voltage between drain and source of Tr1 exceeds the reference voltage for 2μs, short status is detected. (right schematic) 1.Without going through RF resistor, current control does not operate and current will continue to increase in CHARGE mode. 2. If the voltage between drain and source of Tr1 exceeds the reference voltage for 2μs, short status is detected. 1.Without L load, high current flows. 2. If RF voltage> setting voltage, then the mode switches to SLOW decay. 3.During load short state in SLOW decay mode, current does not flow and over current state is not detected. Then the mode is switched to FAST decay according to chopping cycle. 4. Since FAST state is short (≈1μs), switches to CHARGE mode before short is detected. 5.If voltage between drain and source exceeds the reference voltage continuously during blanking time at the start of CHARGE mode (Tr1), CHARGE state is fixed (even if RF voltage exceeds the setting voltage, the mode is not switched to SLOW decay). After 2us or so, short is detected. 35/43 LV8727 Application Note (2) Output short-circuit protection detect voltage (Reference value) Short protector operates when abnormal voltage between drain and source of output Tr exceeds the reference voltage. Ta = 25°C (typ) Upper-side Transistor VDS Lower-side Transistor VDS Reference voltage 3.2V 0.8V (3) Timer latch period Built-in output short-circuit protection circuit makes output to enter in stand-by mode. This function prevents the IC from damaging when the output shorts circuit by a voltage short or a ground short, etc. When output short state is detected for 2µs, short-circuit detection circuit state the operating and output is once turned OFF. Subsequently, the output is turned ON again after the timer latch period (typ. 256μs ). If the output remains in the short-circuit state, turn OFF the output, fix the output to the wait mode. When output is fixed in stand-by mode by output short protection circuit, output is released the latch by setting ST = “L”. Figure 43 . short-circuit protection function timing chart Thermal shutdown function LV8727 incorporates thermal shutdown circuit and the output is turned off when junction temperature Tj exceeds 180°C. When the temperature is lowered to the defined hysteresis, the output is turned on again (automatic restoration). The thermal shutdown circuit does not guarantee the protection of final products where the junction temperature of Tjmax=150°C has already been exceeded. TSD = 180°C (typ) ΔTSD = 40°C (typ) 36/43 LV8727 Application Note Application Circuit Example LV8727 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 M The above sample application circuit is set to the following conditions: Chopping frequency: 55.5kHz (Cosc1 = 180pF) Mixed DECAY mode (FDT=open) The set current value is as follows: IOUT = (Current setting reference voltage / 3) / 0.1Ω 37/43 LV8727 Application Note Allowable power dissipation Specified circuit board: 90mm x 90mm x 1.6mm, glass epoxy 2-layer board Pdmax-Ta Allowable power dissipation, Pdmax-W 6.0 Specified board 5.00 4.0 Indipendent IC 2.60 2.45 2.0 1.27 0.0 -30 0 30 60 90 120 Ambient temperature, Ta-˚C Substrate Specifications (Substrate recommended for operation of LV8727) Size : 90mm × 90mm × 1.6mm (two-layer substrate [2S0P]) Material : Glass epoxy Copper wiring density : L1 = 90% / L2 = 80% L1 : Copper wiring pattern diagram L2 : Copper wiring pattern diagram 38/43 LV8727 Application Note Evaluation board LV8727 (90mm x 90mm x 1.6mm, glass epoxy 2-layer board, with backside mounting) Bill of Materials for LV8727 Evaluation Board Designator C1 C2 C3 R1 R2 R4 R6 Manufacturer Part Number Substitution Allowed Lead Free 100ME100HC yes yes murata GRM1882C1H1 81JA01 yes yes ±5% KOA GRM1882C1H1 52J yes yes 0.1?, 1W ±5% ROHM MCR100JZHJL R10 yes yes 1 Channel 2 output current detective Resistor 0.1?, 1W ±5% ROHM MCR100JZHJL R10 yes yes 1 Pull-up Resistor for for terminal MO 47k?, 1/10W ±5% KOA RK73B1JT473J yes yes 1 VREF stabilization Capacitor 0.1µF, 100V ±10% murata GRM188R72A1 04KA35D yes yes Quantity Value Tolerance 1 Description VM Bypass capacitor Footprint 100µF 100V ±20% Manufacturer SUN Electronic Industries 1 Capacitor to set chopping frequency 180pF, 50V ±5% 1 Capacitor to set switching holding current 1500pF, 50V 1 Channel 1 output current detective Resistor HZIP25 ON semiconductor IC1 1 Motor Driver LV8727 No yes SW1-SW8 8 Switch MIYAMA MS-621-A01 yes yes TP1-TP22 22 Test points MAC8 ST-1-3 yes yes 39/43 ) LV8727 Application Note OUT2A RF2 PGND2 OUT2B VM2 SGND VREF R2: 0.1Ω R6: 0.1uF (R5) R4: 47kΩ (R3) C3: 1500pF C2: 180pF SW8 SW7 SW6 SW5 SW4 SW3 (2) VDD SW2 SW1 MO DOWN FDT OSC2 OSC1 STEP (4) (1) C1: 100uF R1: 0.1Ω (3) FR RST OE MD3 MD2 MD1 ST VM1 OUT1A PGND1 RF1 OUT1B Evaluation board circuit Evaluation Board Manual [Supply Voltage] [Toggle Switch State] VM (9 to 45V): Power Supply for LSI VREF (0 to 3V): Const. Current Control for Reference Voltage VDD (2 to 5V): Logic “High” voltage for toggle switch Upper Side: High (VDD) Middle: Open, enable to external logic input Lower Side: Low (GND) [Operation Guide] 1. Initial Condition Setting: Set “Open” the toggle switch STEP, and “Open or Low” the other switches 2. Motor Connection: Connect the Motors between OUT1A and OUT1B, between OUT2A and OUT2B. 3. Power Supply: Supply DC voltage to VM, VREF and VDD. 4. Ready for Operation from Standby State: Turn “High” the following toggle switches : ST , OE, and RST. Channel 1 and 2 are into Half-Step excitement initial position (100%, 0%). 5. Motor Operation: Input the clock signal into the terminal STEP. 6. Other Setting (See Reference describing operation for detail) i. MD1 , MD2 , MD3 : Micro step resolution. ii. FR: Motor rotation direction (CW / CCW) setting. iii. RST : Initial Mode. iv. OE: Output Enable. v. FDT: DECAY mode. [Setting for External Component Value] 1. Constant Current (100%) At VREF=0.9V Iout =VREF [V] / 3 / RF [ohm] =0.9 [V] / 3 / 0.1 [ohm] =3 [A] 2. Chopping Frequency Fcp = 1 / ( Cosc1 / 10 х 10-6 ) (Hz) -6 =1 / (180 [pF] / 10 х 10 ) (Hz) =55.5 [kHz] 40/43 LV8727 Application Note Waveform of LV8727 evaluation board. ●Figure 44. Half Step VM=24V , VREF=0.45V , VDD=5V ST=H , OE=H , RST=H FR=L MD1=L , MD2=L , MD3=L STEP=0.3kHz (Duty 50%) 5ms/div (1) ●Figure 45. Half Step VM=24V , VREF=0.45V , VDD=5V ST=H , OE=H , RST=H FR=L MD1=L , MD2=H , MD3=L STEP=2.4kHz (Duty 50%) 5ms/div STEP 5V/div (1) STEP 5V/div (2) (2) MO 5V/div (3) (4) (3) Iout1 1A/div Iout2 1A/div ●Figure 46. 1/128 VM=24V , VREF=1.5V , VDD=5V ST=H , OE=L , RST=H FR=L MD1=L , MD2=L , MD3=H STEP=19.2kHz (Duty 50%) 5ms/div MO 5V/div Iout2 1A/div (4) ●Figure 47. 1/20 Step VM=24V , VREF=1.5V , VDD=5V ST=H , OE=H , RST=H FR=L MD1=H , MD2=H , MD3=H STEP=3.0kHz (Duty 50%) 5ms/div (1) STEP 5V/div (1) (2) (2) (4) (3) Iout1 1A/div Iout2 1A/div STEP 5V/div MO 5V/div MO 5V/div (3) Iout1 1A/div (4) Iout1 1A/div Iout2 1A/div 41/43 LV8727 Application Note Warning: ●Power supply connection terminal [VM1, VM2] 9 Make sure to short-circuit VM1 and VM2.For controller supply voltage, the internal regulator voltage of VREG5 (typ 5V) is used. 9 Make sure that supply voltage does not exceed the absolute MAX ratings under no circumstance. Noncompliance can be the cause of IC destruction and degradation. 9 Caution is required for supply voltage because this IC performs switching. 9 The bypass capacitor of the power supply should be close to the IC as much as possible to stabilize voltage. Also if you intend to use high current or back EMF is high, please augment enough capacitance. ●GND terminal [GND, PGND] 9 Since GND is the reference of the IC internal operation, make sure to connect to stable and the lowest possible potential. Since high current flows into PGND, connect it to one-point GND. 9 The exposed die-pad is connected to the board frame of the IC. Therefore, do not connect it other than GND. Independent layout is preferable. If such layout is not feasible, please connect it to signal GND. Or if the area of GND and PGND is larger, you may connect the exposed die pad to the GND. (The independent connection of exposed die pad to PGND is not recommended.) ●Input terminal 9 The logic input pin incorporates pull-down resistor (100kΩ). 9 When you set input pin to low voltage, please short it to GND because the input pin is vulnerable to noise. 9 The input is TTL level (H: 2V or higher, L: 0.8V or lower). 9 FDT input is 3-state level (see pp.15). 9 VREF pin is high impedance. ●OUT terminal [OUT1A, OUT1B, OUT2A, OUT2B] 9 During chopping operation, the output voltage becomes equivalent to VM voltage, which can be the cause of noise. Caution is required for the pattern layout of output pin. 9 The layout should be low impedance because driving current of motor flows into the output pin. 9 Output voltage may boost due to back EMF. Make sure that the voltage does not exceed the absolute MAX ratings under no circumstance. Noncompliance can be the cause of IC destruction and degradation. ●Current sense resistor connection terminal [RF1, RF2] 9 To perform constant current control, please connect resistor to RF pin. 9 To perform saturation drive (without constant current control), please connect RF pin to GND. 9 If RF pin is open, then short protector circuit operates. Therefore, please connect it to resistor or GND. 9 The motor current flows into RF – GND line. Therefore, please connect it to common GND line and low impedance line. 42/43 LV8727 Application Note ON Semiconductor and the ON logo are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of SCILLC’s product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent-Marking.pdf. SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. 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