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L6506 L6506D
CURRENT CONTROLLER FOR STEPPING MOTORS
DESCRIPTION The L6506/D is a linear integrated circuit designed to sense and control the current in stepping motors and similar devices. When used in conjunctionwith the L293, L298, L7150, L6114/L6115, the chip set forms a constant current drive for an inductive load and performs all the interfacefunctionfrom the control logic thru the power stage. Two or more devices may be synchronized using the sync pin. In this mode of operation the oscillator in the master chip sets the operatingfrequencyin all chips. BLOCK DIAGRAM (pin's number referred to DIP-18)
DIP18
SO 20
ORDERING NUMBERS: L6506 L6506D
June 1997
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PIN CONNECTIONS (top view)
DIP 18
SO20
ABSOLUTE MAXIMUM RATINGS
Symb ol VCC Vi Ptot Tj Tstg Supply Voltage Input Signals Total Power Dissipation (Tamb = 70C) for DIP18 Total Power Dissipation (Tamb =70EC) for SO20 Junction Temperature Storage Temperature Parameter Value 10 7 1 0.8 150 -40 to 150 Un it V V W W C C
THERMAL DATA
Symbol R th j-amb Parameter Thermal Resistance Junction-ambient Max. DIP18 80 SO20 100 Unit C/W
ELECTRICAL CHARACTERESTICS (VCC = 5.0V, Tamb = 25C; unless otherwise noted)
Symbol VCC ICC Parameter Supply Voltage Quiescent Supply Current VCC = 7V T est Co nditio ns Min. 4.5 T yp. Max. 7 25 Un it V mA
COMPARATOR SECTION
Symbol VIN VIO IIO IIB Parameter Input Voltage Range Input Offset Voltage Input Offset Current Input Bias Current Response time VREF = 1.4V V SENS = 0 to 5V 0.8 T est Co nditio ns Vsense Inputs VIN = 1.4V Min. -0.3 T yp. Max. 3 5.0 200 1 1.5 Un it V mV nA A s
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ELECTRICAL CHARACTERISTICS (continued) COMPARATOR SECTION PERFORMANCE (Over Operating Temperature Range)
Symbol VIO IIO Parameter Input Offset Voltage Input Offset Curent Test Condtions VIN = 1.4V Min. Typ. Max. 20 500 Unit mV nA
LOGIC SECTION (Over Operating Temperature Range - TTL compatible inputs & outputs)
Symbol VIH VIL VOH VOL IOH Parameter Input High Voltage Input Low Voltage Output High Voltage Ouptut Low Voltage Ouput Source Current - Outputs 1-4 VCC = 4.75V IOH = 400A VCC = 4.75V IOH = 4mA VCC = 4.75V 2.75 2 3.5 0.25 0.4 Test Condtions Min. 2 Typ. Max. Vs 0.8 Unit V V V V mA
OSCILLATOR
Symbol fosc VthL VthH Ri Parameter Frequency Range Lower Threshold Voltage Higher Threshold Voltage Internal Discharge Resistor 0.7 Test Condtions Min. 5 0.33 VCC 0.66 VCC 1 1.3 Typ. Max. 70 Unit KHz V V k
CIRCUIT OPERATION The L6506 is intended for use with dual bridge drivers, such as the L298, quad darlington arrays, such as the L7150, quad DMOS array such as L6114L6115,or discretepower transistors to drive stepper motors and other similar loads.The main functionof the device is to senseand control the currentin each of the load windings. A commonon-chiposcillatordrives thedual chopper and sets the operatingfrequencyfor the pulse width modulated drive. The RC network on pin 1 sets the operating frequency which is given by the equation : 1 f= for R > 10 K 0.69 RC The oscillator provides pulses to set the two flipflops which in turn cause the outputs to activate the drive. When the current in the load winding reaches the programmed peak value, the voltage across the sense resistor (Rsense) is equal to Vref and the corresponding comparator resets its flip-flop interrupting the drive current untilthe next oscillatorpulse occurs. The peak current in each winding is programmed by selecting the value of the sense resis-
tor and Vref. Since separate inputs are provided for each chopper, each of the loads may be programmed independently allowing the device to be used to implement microstepping of the motor. Lowerthreshold of L6506'soscillator is 1/3 VCC. Upper threshold is 2/3 VCC and internal discharge resistor is 1 K 30 %. Ground noise problems in multiple configurations can be avoided by synchronizing the oscillators. This may be done by connecting the sync pins of each of the devices with the oscillator output of the master deviceand connectingthe R/C pin of the unused oscillators to ground. The equations for the active time of the sync pulse (T2), the inactivetime of the sync signal(T1)and the dutycycle canbe foundby lookingat the figure1 and are : R1 RIN T2 = 0.69 C1 (1) R1 + RIN T1 = 0.69 R1 C1 DC = T2 T1 + T2 (2) (3)
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By substituting equations 1 and 2 into equation 3 and solving for the value of R1 the following equations for the external components can be derived : 1 (4) R1 = ( - 2) RIN DC C1 = T1 0.69 R1 (5) Looking at equation 1 it can easily be seen that the minimum pulse width of T2 will occur whenthe value of R1 is at its minimum and the value of R1 at its maximum. Therefore, when evaluating equation 4 the minimum value for R1 of 700 (1 K - 30 %) should be used to guarantee the required pulse width.
Figure 1 : Oscillator Circuit and Waveforms.
APPLICATIONS INFORMATION The circuits shown in figure 2 use the L6506 to implement constant current drives for stepper motors. Figure 2 shows the L6506 used with the L298 to drive a 2 phasebipolarmotor. Thepeak current can be calculated using the equation : Vref Ipeak = Rsense The circuit of Fig.2 can be used in applications requiring different peak and hold current values by modifying the reference voltage.
TheL6506may be used to implement eitherfull step or half step drives. In the case of 2 phase bipolar stepper motor applications, if a half step drive is used, the bridge requires an additional input to disable the power stage during the half step. If used in conjunction with the L298 the enable inputs may be used for this purpose. For quad darlington array in 4 phase unipolarmotor applications half step may be implemented using the 4 phase inputs. The L6506 may also be used to implement microstepping of either bipolar or unipolar motors.
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Figure 2 : Application Circuit Bipolar Stepper Motor Driver. (pin's number referred to DIP18)
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DIP18 PACKAGE MECHANICAL DATA
DIM. MIN. a1 B b b1 D E e e3 F I L Z 3.3 1.27 1.59 8.5 2.54 20.32 7.1 3.93 0.130 0.050 0.063 0.254 1.39 0.46 0.25 23.24 0.335 0.100 0.800 0.280 0.155 1.65 mm TYP. MAX. MIN. 0.010 0.055 0.018 0.010 0.915 0.065 inch TYP. MAX.
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SO20 PACKAGE MECHANICAL DATA
DIM. MIN. A a1 a2 b b1 C c1 D E e e3 F L M S 7.4 0.5 12.6 10 1.27 11.43 7.6 1.27 0.75 8 (max.) 0.291 0.020 13.0 10.65 0.35 0.23 0.5 45 (typ.) 0.496 0.394 0.050 0.450 0.299 0.050 0.030 0.512 0.419 0.1 mm TYP. MAX. 2.65 0.3 2.45 0.49 0.32 0.014 0.009 0.020 0.004 MIN. inch TYP. MAX. 0.104 0.012 0.096 0.019 0.013
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Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. (c) 1997 SGS-THOMSON Microelectronics - Printed in Italy - All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco The Netherlands - Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A.
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