Panasonic Stepping Motor Driver AN44067A Application note

Transcription

1 Panasonic Stepping Motor Driver AN44067A Application note 1

2 Contents 1.Overview / Feature 2.Block diagram 3.Application circuit 4.Internal voltage 4-1.S5VOUT Output 4-2.Charge pump voltage 5.Input I/F 5-1.Control Mode 5-2.Input I/F circuit 5-3.Set / Hold time 6.Position control 6-1.Initial position 6-2.Reverse Change excitation Change excitation Specification of ENABE P4 P5 P6 P7 P8 P9 P10 P11 P12~14 P15 P16 P17 P18 2

3 Contents (continued) 7.Torque control 7-1.Calculation formula of motor current 7-2.Min-Duty 8.Protection circuit 8-1.Under voltage lockout (UVO) 8-2.Thermal protection 8-3.Ground fault protection 8-4.Timing of ground fault protection 9.Heat evaluation 9-1.How to measurement of chip temperature 9-2.Calculation formula of power consumption 10.Notes for PCB 10-1.Notes for VM and GND wiring in the PCB 10-2.Notes for the PCB wiring in the terminal of interface and mode setting P19 P20 P21 P22 P23 P24 P25 P26 P27 P28 3

4 1.Overview/Feature AN44067A Driver IC for Stepping Motor (1)Overview AN44067A is s two channel H-bridge driver IC. Bipolar stepping motor can be controlled by a single driver IC. 2-2 phase excitation,half- step,1-2 phase excitation,w1-2 phase excitation and 2W1-2 phase excitation can be selected. (2)Feature 1,Built-in decoder for micro steps (2 phase excitation, half-step, 1-2 phase excitation, W1-2 phase excitation and 2W1-2 phase excitation) Stepping motor can be driven by only external clock signal. 2,PMW can be driven by built-in CR (3-value can be selected during PWM OFF period.) 3,Mix Decay control can improve accuracy of motor current wave form. (4-value for Fast Decay ratio can be selected.) 4,Built -in under voltage lockout (UVO) When supply voltage lowers less than the operating supply voltage range, UVO operates and all motor outputs are turned OFF. 5,Built-in thermal protection When chip junction temperature rises and reaches setup temperature, all motor outputs are turned OFF. 6,1 power supply with built-in 5 V power supply (accuracy ±5%) 7,Built-in standby function Operation of standby function can lower current consumption of IC. 8,Built-in Home Position function Home Position function can detect the position of a motor. (3)Applications : PPC, Printer, Fax, Security Camera, Medical equipment, Robot, ATM, FA, Home appliance etc. (4)Package : 34 pin Plastic Small Outline Package With Heat Sink (SOP Type) (5)Type : Bi-CDMOS IC 4

5 2.Block diagram 0.01uF Input I/F ENABE 19 TJMON 3 PWMSW 33 Input I/F TEST 25 VREF 23 DECAY1 21 DECAY uF S5VOUT 24 Input I/F BC1 13 BC2 14 PHA 28 DIR 32 ST1 31 ST2 30 ST3 29 STBY 22 TES T Micro Step Decoder AMP Internal voltage DAC2 1/10 CHARGE PUMP PWMSW 1/10 DAC1 Posotion control BG R STBY R S Q BANK Charge pump Voltage QS VM OSC TSD Gate Circuit Gate Circuit VM VM Ground fault protection Ground fault protection S5VOUT UVO UVO AOUT1 AOUT2 BOUT1 BOUT2 15 VPUMP 6 BOUT2 7 RCSB 8 BOUT1 1 VM2 Protection circuit 17 VM1 10 AOUT2 11 RCSA 12 AOUT1 27 GND 4 GND 0.01uF(50V) Protection circuit 47uF 0.1uF - + Protection circuit M 5

6 VREF PGNDA 3.Application Circuit GND PGNDB VCC JP2 S9 S7 S8 R1 =10 S6 JP1 OPEN SGND S5 S4 S3 S2 S1 PGNDC VR1 50k C7 103 PHA1 C5 104 S5VOUT ENABE N.C. DIR ST1 ST2 ST3 PHA GND GND TEST S5VOUT VREF STBY DECAY1 DECAY2 N.C. PWMSW AN44067 (PKG:HTUSONF-34D) VM2 NC TJMON GND N.C. BOUT2 RCSB BOUT1 GND AOUT2 RCSA AOUT1 BC1 BC2 VPUMP N.C. VM VPUMP C2 103 RCSA W RCSB W TJMON C1 103 C C3 50V/47uF AOUT1 AOUT2 BOUT1 BOUT2 To motor 6

7 4.Internal voltage 4-1 S5VOUT output It needs rising time of S5VOUT voltage when this IC change from stand-by mode to non-stand-by mode. Because output voltage of S5VOUT is OFF (0V) when this IC is stand-by mode. rising time of S5VOUT voltage : 40us(Typ) -> capacity between S5VOUT and GND : 0.1uF This IC has all outputs OFF period of about 140 us (typ) after this IC change from stand-by mode to non-stand-by mode (Refer to the below figure). Because this is why restart from Stand-by is performed after S5VOUT voltage rises sufficiently because S5VOUT voltage is off at Stand-by mode. This all outputs OFF period influences the capacity between S5VOUT and GND. [stand-by mode : OFF (STBY =H) ] STBY "" "H" S5VOUT S5VOUT:OFF(0V) S5VOUT: rising time S5VOUT: ON about 40 us(typ) OUTPUT all output is off all output is off Ground fault detection start (when ENABE = "") all output is off (when ENABE = "H") about 140 us(typ) about 5.5 us(typ) * Condition : capacity between S5VOUT and GND 0.1uF 7

8 4.Internal voltage 4-2 Charge pump voltage This IC has all outputs OFF period of about 140 us (typ) when this IC change from stand-by mode to non-stand-by mode and ow voltage protection (Refer to the below figure). This is why restart from Standby and ow voltage protection is performed after charge pump voltage rises sufficiently because charge pump operation stops at stand-by mode and ow voltage protection. rising time : 80us(Typ) -> Condition : capacity between BC1 and BC2:0.01uF, capacity between VPUMP and GND:0.01uF,capacity between S5VOUT and GND:0.1uF When the charge pump voltage does not rise sufficiently during all outputs OFF period due to that capacitance between VPUMP and GND becomes large etc, the IC might overheat. In this case, release Standby and ow voltage protection at ENABE = High-level, and restart at ENABE = ow-level after the charge pump voltage rises sufficiently. [stand-by mode : OFF (STBY =H) ] STBY "" "H" ENABE "H" "" VPUMP Charge pump :OFF Charge pump :ON about 80 us(typ) OUTPUT all output is off all output is off Ground fault detection start (when ENABE = "") all output is off (when ENABE = "H") about 140 us(typ) abtou 5.5 us(typ) 8

9 5.Input I/F 5-1 Control mode Table1 excitation method ENABE DIR ST1 ST2 ST3 Excitation mode DIR= -> Phase B 90deg delay to Phase A DIR=H ->Phase B 90deg advance to Phase A H Output OFF /H 2 phase excitation drive (4-step sequence) /H H Half-step drive (8-step sequence) /H H 1-2 phase excitation drive (8-step sequence) /H H H W1-2 phase excitation drive (16-step sequence) /H - - H 2W1-2 phase excitation drive (32-step sequence) STBY H H Table2 Stand-by / Enable control ENABE - H Control /charge pump OFF ON ON Output Power MOS transistor OFF OFF ON Table4 Decay method DECAY1 DECAY2 Decay Slow Decay H Fast 25% H Fast 50% H H Fast 100% Table 3 PWMSW(OFF Period) PWMSW PWM Period 28.0us M 15.2us H 8.8us Table5 TEST TEST TJMON VBE monitor M TEST Output H Home Position 9

10 5.Input I/F 5-2 Input I/F circuit It show input circuit of input I/F in the following. 19 ENABE 20 DECAY2 21 DECAY1 28 PHA 29 ST3 30 ST2 31 ST1 32 DIR 4k 100k 22 STBY 32k 68k 23 VREF 4k 4k 33 PWMSW 140k 25 TEST 4k 4k S5VOUT (Pin24) Diode 60k 100k Ground 10

11 5.Input I/F 5-3 Set / Hold time The set/hold time of PHA and DIR input signals, PHA input minimum pulse width (High/ow) are shown as the below figure. Input signals after securing set/hold time. PHA(CK) C D A B DIR Period A B C D Contents PHA input minimum pulse width (High) PHA input minimum pulse width (ow) DIR set time DIR hold time Time 5 ms or more 5 ms or more 2 ms or more 2 ms or more 11

12 6.Position control Initial position Initial position : when supply voltage rise / fall, stand-by mode is on/ off ex.1-2 phase excitation more than 200usec CK VM / Stand-by A-ch. Motor current <- motor current is 0A when supply voltage fall and stand-by is on. <- initial position is fixed each excitation mode when supply voltage rise and stand-by mode is off. initial position of each excitation mode is as shown in the figure below. B-ch. Motor current Motor current :0 Table initial position of each excitation mode (DIR=) motor current is initial position of each excitation mode when supply voltage rises AOUT1 current +100% Excitation mode 2 phase excitation (4 step) Half-step (8 step) 1-2 phase excitation (8 step) W1-2 phase excitation (16 step) 2W1-2 phase excitation (32 step) Default electrical angle 45deg 0deg 0deg 0deg 0deg Next step 45deg 45deg 45deg 22.5deg 11.25deg 0deg -100% Half step/1-2/w1-2 /2W1-2 phase excitation initial position 45deg 2 phase initial position Foward Foward Reverse Reverse -100% BOUT1 current +100% 12

13 6.Position control Initial position1 (detail) STBY A-ch. motor current B-ch. motor current DIR = ow PHA (CK) more than 200usec after 1CK motor is held initial position after stand-by mode is off. <- CK input Please input CK when it pass 200usec after stand-by is off. excitation mode :Half~2W1-2phase <- initial position when it pass about 140usec after stand-by is off. AOUT1 current = 0% BOUT1 current =-100% afterward it start by input of PHA. after 1CK 2phase / Half excitation after 1CK W1-2phase excitation after 1CK 2W1-2phase excitation Initial position1-100% AOUT1 current after 1CK 1-2phase excitation about 140usec all outputs is off +100% BOUT1 current +100% excitation mode : 2 phase initial position : it pass about 140usec after stand-by mode is off. AOUT1 current =-100% BOUT1 current =-100% afterward it start by input of PHA. initial position of each excitation mode is as follows. Half~2W1-2 phase => initial position 1 2 phase => initial position 2 Initial position2-100% 13

14 6.Position control Initial position2 (detail) PHA (CK) STBY A-ch. motor current B-ch. motor current DIR = High more than 200usec after 1CK motor is held initial position after stand-by is off. <- CK input Please input CK when it pass 200usec after stand-by is off. excitation mode :Half~2W1-2phase <- initial position when it pass about 140usec after stand-by is off AOUT1 current = 0% BOUT1 current = -100% afterward it start by input of PHA. AOUT1 current about 140usec +100% excitation mode : 2 phase initial position : it pass about 140usec after stand-by is off. AOUT1 current =-100% BOUT1 current =-100% afterward it start by input of PHA. -100% Initial position1 after 1CK 2W1-2phase excitation after 1CK W1-2phase excitation after 1CK Half step excitation Initial position2 after 1CK 1-2phase excitation -100% +100% BOUT1 current after 1CK 2phase excitation initial position of each excitation mode is as follows. Half~2W1-2 phase => initial position 1 2 phase => initial position 2 14

15 6.Position control 6-2 Reverse The state of motor is held and move continuously when it changes the rotation direction of motor by terminal of DIR (ex.)timing chart when 1-2phase excitation mode V PHA DIR A-ch. DAC output B-ch. DAC output A-ch. Phase B-ch. Phase A-ch. motor current B-ch. motor currnt 15

16 6.Position control Excitation mode change1 CK It can not hold position of motor before change excitation mode when it change excitation mode. Position of motor change corresponding to each states1-32 as shown in below figure when it change excitation mode. IAOUT1 2W1-2phase IBOUT1 IAOUT1 W1-2phase IBOUT1 IAOUT1 1-2phase IBOUT1 IAOUT1 IBOUT1 Home Position 2phase 16

17 6.Position control Excitation mode change 2 It can not hold position of motor before change excitation mode when it change excitation mode. If it change excitation mode when it is timing that Home Position is ow voltage, displacement of motor state is small. case1 : excitation mode before and after change excitation mode is without 2 phase, there is not displacement of motor state after and before change excitation mode. case2 : either excitation mode before and after change excitation mode is 2 phase there is displacement of motor state after and before it change excitation mode. but displacement of motor state is within 45deg in electric degree. Table motor current of each excitation mode when Home Position = ow 2 phase Half 1-2phase W1-2phase 2W1-2phase A phase current 100% 0% 0% 0% 0% B phase current 100% 100% 100% 100% 100% It need as follows in case of using Home Position it input terminal of TEST High-voltage (more than 4V). it connect supply voltage (less than 6V) terminal of TJMON. TJMON 3 AN44067 V 17

18 6.Position control 6-4 Specification of ENABE This IC accept CK(PHA) signal when it is ENABE=H. So if it restarts motor from position that motor stopped, It stop inputting to terminal of PHA when it stop motor by ENABE=H. In spite of stop at state[6], because PHA is input at ENABE = High, the motor will restart after ENABE = ow at state [3]. Ex.1-2phase excitation PHA (CK) A-ch. motor current <- when inputting PHA at the time of motor stop and ENABE = High, all outputs is off by ENABE=High, so motor current is zero. afterward it restart by ENABE=low-voltage the setup value of motor current will proceed at PHA input. ENABE In spite of stop at state [6], because PHA is not input at ENABE = High, the motor will restart after ENABE = ow at state [6] just before stop. PHA (CK) A-ch. motor current <- when not inputting PHA at the time of motor stop and ENABE = High all outputs is off by ENABE=High, so motor current is zero. afterward when it restart by ENABE = low-voltage, motor start from same motor state before it stop inputting CK ENABE 18

19 7.Torque control 7-1 Calculation formula of motor current Motor current can be set by RSC resistance for motor current detection and VREF of reference voltage. maximum of motor current is as follows. I PEAK 1 = VREF 10 1 Rcs For example, if it want set maximum of motor current 1.0A it set as follow by above calculation formula. Rcs 1 = 2.0( V ) (A) = 0.20( ) [note] If terminal of VREF is open, VREF voltage is unstable and rise, it may follow big current in the this IC. Therefore terminal of VREF do not use in open. 19

20 7.Torque control 7-2 Min-Duty This IC has pulse blanking time (0.7 us/ Typ.value) to prevent erroroneous current detection caused by noise. Therefore, the motor current value will not be less than current determined by pulse blanking time. Pay attention at the time of minimum current control. The relation between pulse blanking time and minimum current is shown as below figure. In addition, minimum value of motor current value is determined by value, wire wound resistance, induced voltage and PWM on Duty inside a motor. Setup current value A Setup current value B Minimum current value Setup current value C T ONA T ONB T B f PWM f PWM f PWM f PWM : PWM freqency T ON : PWM ON-time T B : pulse blanking time ( Typ = 0.7us ) *Above figure setup current value A and B -> ON-Duty>Min-Duty -> motor current control according to the setting of motor current. setup current value C -> Min-Duty control -> motor current is limited 20

21 8.Protection circuit 8-1 Under voltage lockout (UVO) This IC has under-voltage lockout (UVO) of VM supply voltage. All motor outputs are turned off when UVO operates. Operation of UVO Signal of UVO Vhys H:not detection VM:24V -> 0V VM:0V -> 24V threshold value (V2)=7.9V (Typ) threshold value (V1)=8.7V (Typ) :detection V2=7.9V V1=8.7V VM VM voltage range that all outputs is off supply voltage rise : 0V~8.7V supply voltage fall : less than 7.9V 21

22 8.Protection circuit 8-2 Thermal protection This IC have thermal protection circuit. All outputs is off when it operates thermal protection. Operation of thermal protection It rise in temperature (TSD_ON)=150degC(Typ) It fall in temperature (TSD_OFF)=110degC(Typ) H:not operation of Thermal protection :operation of Thermal protection Thermal protection detection signal hys Temp Chip temperature that all outputs is off temperature of chip is more than 150degC temperature of chip is less than 110degC after operate thermal protection Thermal protection operation is self-return type. Therefore it repeat as follows. all outputs is off -> return (motor operate) -> all outputs is off -> return -> TSD_OFF TSD_ON 22

23 8.Protection circuit 8-3 Ground fault protection This IC have ground fault protection. All outputs is off when it operates ground fault protection. Ground fault detection operation VM Upper power of Ach and Bch are ON when it operate ground fault detecting operation. Then if difference voltage between VM and motor output is more than threshold voltage, it hold all outputs off. ON OUT1 V M V OUT2 ON Ground fault detection threshold value : 7V (voltage between VM and motor output) state that all outputs are off can release below method. terminal of STBY is low voltage and restart this IC. VM supply voltage is fall and restart this IC. OFF OFF But ground fault protection circuit do not insure protection of user s set and function of this IC. Therefore it do not design protection circuit of set using function of ground fault protection circuit. For the ground fault protection circuit, if the area of safe operation or the absolute maximum rating is momentarily exceeded, the this IC might be damaged before the ground fault protection circuit could operate. 23

24 8.Protection circuit 8-4 Timing of ground fault protection [when stand-by is off ] STBY "" "H" Ground fault detection the former page operates as three timing of follows. Stand-by Stand-by Non-stand-by Motor output All outputs is off All outputs is off Ground fault detection start (when ENABE = "") all output is off (when ENABE = "H") about 140 us(typ) [when it release low-voltage protection] about 5.5 us(typ) VM Motor output "" All outputs is off (low-voltage protection) "H" All outputs is off Ground fault detection start (when ENABE = "") all output is off (when ENABE = "H") Ground fault protection Circuit do not operate After timing drawing left figure [when it release thermal protection] about 140 us(typ) about 5.5 us(typ) TSD "" "H" Motor output All outputs is off (thermal protection) All outputs is off Ground fault detection start (when ENABE = "") all output is off (when ENABE = "H") about 140 us(typ) about 5.5 us(typ) 24

25 9.Heat evaluation 9-1 How to measurement of chip temperature This IC have terminal (TJMON) for evaluating chip temperature. It can guess chip temperature in below reference figure. Evaluation method If it evaluate chip temperature by method of left figure, Terminal of TJMON is open and it input terminal of TEST is low voltage (less than 0.6V). VBE[V] temperature Characteristic of VBE Chip temperature is calculated by difference voltage of TJMON voltage between before and after motor operating. Delta VBE / delta temp = [mv / degc] V Temp = BE ( t 2 ) V BE 3 ( t 1 ) Temp[degC] [note] please design about fever with enough margin and evaluation It is recommended to design to set connective parts to 70% to 80% of maximum rating. TJMON 3 V AN

26 9.Heat evaluation 9-2 Calculation of power consumption Power consumption becomes the total of the item (from A to F) of the following figure. Output Voltage PWM Wave form A B C D E F Switching loss(=a+e) Regeneration (=B+D) Synchronous rectification(=c) Charge(=F) 1 P Switch = VM I Motor ( t + t 2 P rege P Sync P Gene DI Motor 2 Motor Switch1 Switch 2 = ( V I + I R ) t = 2 I 2 Motor 2 Motor R Up Up t Sync = I ( R + R ) t o Up Gene dead ) Regeneration Switching loss1 Synchronous rectification Regeneration 1/fPWM Charge Switching loss2 time Power consumption P PWM = ( P + P + P + P ) Switch rene Sync VM : Power supply voltage Imotor : Motor current Rup : Resistance of upper output transistor Rlo : Resistance of upper output transistor Vdi : Diode voltage Tdead : Synchronous rectification time fpwm : PWM frequency Gene f PWM 26

27 10.Notes for PCB 10-1 Notes for VM and GND wiring in the PCB Design the VM and GND wiring drawn thick lines as thick and short as possible 0.1uF The wiring beside GND of the capacitor between S5VOUT and GND is as short as possible N.C. PWMSW DIR ST1 ST2 ST3 PHA GND GND TEST S5VOUT VREF STBY DECAY1 DECAY2 ENABE N.C. Exposed thermal GND pattern VM2 Design the exposed thermal GND pattern as large as possible for sinking the heat of this IC. 1 NC TJMON GND N.C. BOUT2 RCSB BOUT1 GND AOUT2 RCSA AOUT1 BC1 BC2 VPUMP N.C VM1 17 RCSB RCSA 47uF 0.1uF short GND wiring at the this one point GND VM 27

28 10.Notes for PCB 10-2 Notes for the PCB wiring in the terminal of interface and mode setting 1,The terminal of Interface Consider the wiring pattern of ENABE,PHA,DIR,ST1,ST2,ST3,STBY terminal without the crosstalk for motor output terminals. It shorts these terminals (except the STBY terminal) to GND or S5VOUT in case it does not use these terminals for interface and it keeps fixing the given voltage to these terminals. 2,The terminal setting mode Short the DECAY1 and DECAY2 and TEST terminal to GND or S5VOUT for mode setting. The mode setting by the PWMSW terminal is three points (H / M / ). DECAY1 S5VOUT GND Internal circuit AN44067A Short the PWMSW terminal to the GND terminal if the mode setting by PWMSW is. Short the PWMSW terminal to the S5VOUT terminal if the mode setting by PWMSW is H. It is open the PWMSW terminal if the mode setting by PWMSW is M. But it may occur the fault due to noise when it set the PWMSW terminal open. Therefore connect the capacity of 0.01uF between PWMSW and GND. 0.01uF PWMSW GND S5VOUT 140k 60k Internal circuit AN44067A 28

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