2-Phase Stepper Motor Unipolar Driver ICs

Transcription

1 -Phase/- Phase Excitation -Phase Stepper Motor Unipolar Driver ICs Absolute Maximum Ratings Parameter Symbol Ratings SLA77MU SLA74M SLA76M Units Motor supply voltage CC 46 FET Drain-Source voltage DSS Control supply voltage S 46 TTL input voltage IN 7 Reference voltage REF Output current IO. 3 A Power dissipation PD 4. (Without Heatsink) W PD 3 (TC= C) W Channel temperature Tch C Storage temperature Tstg 4 to C (Ta= C) Electrical Characteristics DC characteristics AC characteristics Ratings Parameter Symbol SLA77MU SLA74M SLA76M Units min typ max min typ max min typ max Control supply current IS Condition S=44 S=44 S=44 ma Control supply voltage S FET Drain-Source voltage FET ON voltage FET drain leakage current FET diode forward voltage TTL input current DSS Condition S=44, IDSS=µA S=44, IDSS=µA S=44, IDSS=µA DS Condition ID=A, AS=4 ID=A, S=4 ID=3A, S=4 IDSS Condition DSS=, S=44 DSS=, S=44 DSS=, S=44 ma SD...3 Condition ID=A ID=A ID=3A IIH Condition IH=.4, S=44 IH=.4, S=44 IH=.4, S=44 µa IIL Condition IL=.4, S=44 IL=.4, S=44 IL=.4, S=44 ma IH TTL input voltage Condition ID=A ID=A ID=3A (Active High) IL Condition DSS= DSS= DSS= IH TTL input voltage Condition DSS= DSS= DSS= (Active Low) IL Condition ID=A ID=A ID=3A Tr... Condition S=4, ID=.8A S=4, ID=A S=4, ID=A Switching time Tstg Condition S=4, ID=.8A S=4, ID=A S=4, ID=A µs Tf... Condition S=4, ID=.8A S=4, ID=A S=4, ID=A

2 Internal Block Diagram IN A IN A SA SB IN B IN B Reg Reg, 8,, 8pin Description of pins Excitation input Active H Active L Pin OUTA OUTA Pin 8 OUTA OUTA Pin OUTB OUTB Pin 8 OUTB OUTB RSA 9 GA 4 TDA REFA 3 REFB TDB GB RSB 4 3 Diagram of Standard External Circuit(Recommended Circuit Constants) Active High b () r3 CC (46 max) C r4 C r SA SB OUTA OUTAOUTB OUTB TdA TdB 3 RSA REFA REFB RSB GA GB C3 C4 SLA74M 76M 77MU Active High Excitation signal time chart -phase excitation clock 3 H L L H H L L H H L L H H H L L H H L L H H L L - phase excitation clock H H L L L L L H H H L L L L L H H H L L L L L H L H H H L L L L L H H H L L L L L H H H L L L L : Ω r : Ω (R) r3 : 47kΩ r4 : 47kΩ :.4kΩ :.4kΩ C : 47pF C : 47pF C3 : pf C4 : pf : Ω typ(74m) ( to W).68Ω typ(76m).8ω typ(77mu) Active Low b () r3 CC (46 max) C r4 C r SA SB OUTA OUTA OUTB OUTB TdA TdB 3 RSA REFA REFB RSB GA GB C3 C4 SLA74M 76M 77MU Active Low Excitation signal time chart -phase excitation clock 3 L H H L L H H L L H H L L L H H L L H H L L H H - phase excitation clock L L H H H H H L L L H H H H H L L L H H H H H L H L L L H H H H H L L L H H H H H L L L H H H H : Ω r : Ω(R) r3 : 47kΩ r4 : 47kΩ :.4kΩ :.4kΩ C : 47pF C : 47pF C3 : pf C4 : pf : Ω typ(74m) ( to W).68Ω typ(76m).8ω typ(77mu)

3 External Dimensions (Unit: mm) φ 3. ±. 3 ±. 4.4 ±. 6.4 ±. φ 3. ± ±..7 ±. 6 ±. 3 ±. 9.9 ±..6.. Part No. Lot No. 7 P.68 ±.4 =8.6 ± R-End.4 ±. 6.7 ±. (3) ± P.68 ±.4 =8.6 ±. ±.6 6 ±.6 7. ±.6 3 ± ± ± ± Forming No. No.87 Forming No. No.87

4 Application Notes Determining the Output Current Fig. shows the waveform of the output current (motor coil current). The method of determining the peak value of the output current (IO) based on this waveform is shown below. (Parameters for determining the output current IO) b: Reference supply voltage,r: oltage-divider resistors for the reference supply voltage RS: Current sense resistor () Normal rotation mode IO is determined as follows when current flows at the maximum level during motor rotation. (See Fig..) IO () Power down mode The circuit in Fig.3 (rx and Tr) is added in order to decrease the coil current. IO is then determined as follows. IOPD Equation () can be modified to obtain equation to determine rx. rx= r b... () r RS (rrx) r rx b IOPD b... () RS r Fig. 4 and show the graphs of equations () and () respectively. Fig. Waveform of coil current (Phase A excitation ON) Phase A Phase A Fig. Normal mode b( ) 3,(4) r C3 9,() RS Fig. 3 Power down mode b( ) 3,(4) IO rx r 9,() Power down signal Tr C3 Fig. 4 Output current IO vs. Current sense resistor RS Fig. Output current IOPD vs. ariable current sense resistor rx 4. 3 r b IO= r RS =Ω r=ω rx= b= Output current IOPD (A)... RS =.Ω RS =.8Ω RS =Ω IOPD= b (rrx) RS r rx =Ω r=ω b= 3 4 Current sense resistor RS (Ω) ariable current sense resistor rx (Ω) (NOTE) Ringing noise is produced in the current sense resistor RS when the MOSFET is switched ON and OFF by chopping. This noise is also generated in feedback signals from RS which may therefore cause the comparator to malfunction. To prevent chopping malfunctions, () and C3(C4) are added to act as a noise filter. However, when the values of these constants are increased, the response from RS to the comparator becomes slow. Hence the value of the output current IO is somewhat higher than the calculated value. 3

5 f (khz) f (khz) Determining the chopper frequency Fig. 6 Chopper frequency vs. Motor coil resistance Determining TOFF The SLA7M series are self-excited choppers. The chopping OFF time TOFF is fixed by r3/c and r4/c connected to terminal Td. TOFF can be calculated using the following formula: TOFF r3 C rn ( = r4 C rn ( ) b b The circuit constants and the TOFF value shown below are recommended. TOFF = µs at r3=47kω, C=pF, b= ON time TON ( s) µ CC =4 CC = Chopping frequency f (khz) r3 r4 C = C = 47kΩ pf TOFF = µ s RS =Ω Lm =~3ms Rm Motor coil resistance Rm (Ω) Chopper frequency vs. Supply voltage Chopper frequency vs. Output current Motor : 3LM-C IO =.8A at CC=4 RS=Ω 3 Motor : 3LM-C CC=4 RS=Ω 3 4 CC () IO (A) 4

6 Case temperature rise TCa ( C) Case temperature rise TCa ( C) Case temperature rise TCa ( C) Heat dissipation per phase PH (W) Heat dissipation per phase PH (W) Thermal Design An outline of the method for calculating heat dissipation is shown below. () Obtain the value of PH that corresponds to the motor coil current IO from Fig. 7 "Heat dissipation per phase PH vs. Output current IO." () The power dissipation Pdiss is obtained using the following formula. -phase excitation: Pdiss PH. S (W) 3 - phase excitation: Pdiss PH. S (W) (3) Obtain the temperature rise that corresponds to the calculated value of Pdiss from Fig. 8 "Temperature rise." Fig. 7 Heat dissipation per phase PH vs. Output current IO. SLA77MU 4. SLA76M CC = Motor : 3LM-C 3... CC = Motor : 3PM-C SLA74M Fig. 8 Temperature rise Heat dissipation per phase PH (W) CC = Motor : 3LM-C4 ( C) Tja TCa Tj TC 3 4 Total Power (W) Thermal characteristics SLA77MU SLA76M TC ( 4 pin) 3 TC( 4 pin) Motor : PH6-B Motor current IO=.8A Ta= C CC=4, S=4 -phase excitation Motor : 3PM-C7 Motor current IO=.A Ta= C CC=4, S=4 -phase excitation K Response frequency (pps) K K Response frequency (pps) 3 SLA74M TC ( 4 pin) Motor : PH6-B Motor current IO=.8A Ta= C CC=4, S=4 -phase excitation K Response frequency (pps)

7 Supply current ICC (ma) Supply current ICC (ma) Supply current ICC (A) Supply oltage CC vs. Supply Current ICC SLA77MU. SLA76M 4 3 IO=A Motor : 3LM-C -phase excitation IO : Output current.. IO=3A Motor : 3PM-C3 -phase excitation IO : Output current.4a.a IO=A IO=A 3 4 Supply voltage CC () 3 4 Supply voltage CC () SLA74M Supply voltage CC () IO=A.A.A Motor : 3LM-C4 -phase excitation IO : Output current Note The excitation input signals of the SLA77MU, SLA74M and SLA76M can be used as either Active High or Active Low. Note, however, that the corresponding output (OUT) changes depending on the input (IN). Active High Active Low Input (pin6) (pin) Corresponding output OUTA (pin) OUTA (pin8) Input (pin6) (pin) Corresponding output OUTA (pin8) OUTA (pin) (pin7) (pin6) OUTB (pin) OUTB (pin8) (pin7) (pin6) OUTB (pin8) OUTB (pin) 6