PBL3717A STEPPER MOTOR DRIVER . .. . .. . . FULL STEP - HALF STEP - QUARTER STEP OPERATING MODE BIPOLAR OUTPUT CURRENT UP TO 1 A FROM 10 V UP TO 46 V MOTOR SUPPLY VOLTAGE LOW SATURATION VOLTAGE WITH INTEGRATED BOOTSTRAP BUILT IN FAST PROTECTION DIODES EXTERNALLY SELECTABLE CURRENT LEVEL OUTPUT CURRENT LEVEL DIGITALLY OR ANALOGUE CONTROLLED THERMAL PROTECTION WITH SOFT INTERVENTION Powerdip 12 + 2 + 2 (Plastic Package) ORDER CODE : PBL3717A DESCRIPTION PIN CONNECTION (top view) The PBL3717Ais a monolithic IC which controls and drives one phase of a bipolar stepper motor with chopper control of the phase current. Current levels may be selected in threesteps by means of two logic inputs which select one of three current comparators. When both of these inputs are high the device is disabled. A separate logic input controls the direction of current flow. A monostable, programmed by an external RC network, sets the current decay time. The power section is a full H-bridge driver with four internal clamp diodes for current recirculation. An externalconnectionto the lower emitters is available for the insertion of a sensing resistor. Two PBL3717As and few external components form a complete stepper motor drive subsystem. The raccomended operating ambient temperature ranges is from 0 to 70 °C. The PBL3717Ais supplied in a 12 + 2 + 2 lead Powerdip package. April 1993 1/11 PBL3717A PIN FUNCTIONS N° Name Function 1 UTPUT B Output Connection (with pin 15). The output stage is a ”H” bridge formed by four transistors and four diodes suitable for switching applications. 2 PULSE TIME A parallel RC network connected to this pin sets the OFF time of the lower power transistors. The pulse generator is a monostable triggered by the rising edge of the output of the comparators (toff = 0.69 RT CT). 3 SUPPLY VOLTAGE B 4 GROUND Supply Voltage Input for Half Output Stage See also pin 14. Ground Connection. With pins 5, 12 and 13 also conducts heat from die to printed circuit copper. 5 GROUND 6 LOGIC SUPPLY See pin 4. 7 INPUT 1 This pin and pin 9 (INPUT 0) are logic inputs which select the outputs of the three comparators to set the current level. Current also depends on the sensing resistor and reference voltage. See truth table. 8 PHASE This TTL-compatible logic input sets the direction of current flow through the load. A high level causes current to flow from OUTPUT A (source) to OUTPUT B (sink). A schmitt trigger on this input provides good noise immunity and a delay circuit prevents output stage short circuits during switching. 9 INPUT 0 See INPUT 1 (pin 7) . 10 COMPARATOR INPUT Input connected to the three comparators. The voltage across the sense resistor is feedback to this input through the low pass filter RC CC. The lower power transistor are disabled when the sense voltage exceeds the reference voltage of the selected comparator. When this occurs the current decays for a time set by RT CT, toff = 0.69 RT C T. 11 REFERENCE A voltage applied to this pin sets the reference voltage of the three comparators, this determining the output current (also thus depending on R s and the two inputs INPUT 0 and INPUT 1). 12 GROUND Supply Voltage Input for Logic Circuitry See pin 4. 13 GROUND 14 SUPPLY VOLTAGE A See pin 4. 15 OUTPUT A 16 SENSE RESISTOR Supply Voltage Input for Half Output Stage. See also pin 13. See pin 1. Connection to Lower Emitters of Output Stage for Insertion of Current Sense Resistor TRUTH TABLE Inpu t 0 (pin 9) Input 1 (pin 7) H L H L H H L L 2/11 No Current Low Current Medium Current High Current PBL3717A BLOCK DIAGRAM ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit Vs Power Supply Voltage 50 V Vss Logic Supply Voltage 7 V Vi Logic Input Voltage 6 V Vc Comparator Input Vr Reference Input Voltage 15 V Io Output Current (DC operation) 1.2 A – 55 to + 150 °C 150 °C Tstg Tj Vss Storage Temperature Operating Junction Temperature THERMAL DATA Symbol Value Unit Rth j-case Thermal Resistance Junction-pins Parameter 11 °C/W Rth j-amb Thermal Resistance Junction-ambient* 40 °C/W * Soldered on a 35µ thick 20 cm2 P.C. board copper area. 3/11 PBL3717A ELECTRICAL CHARACTERISTICS (refer to the test circuit VS = 36V, VSS = 5V, Tamb = 25oC unless otherwise specified) Symbol Parameter Vs Supply Voltage (pin 3, 14) Vss Logic Supply Voltage (pin 6) Iss Logic Supply Current (pin 6) IR Reference Input Current (pin 11) Test Conditions Min. Max. Unit 10 46 V 4.75 5.25 V 7 15 mA 0.75 1 mA 0.8 V VR = 5V Typ. LOGIC INPUTS ViL Input Low Voltage (pins 7, 8, 9) ViH Input High Voltage (pin 7, 8, 9) IiL Low Voltage Input Current (pins 7, 8, 9) Vi = 0.4V IiH High Voltage Input Current (pins 7, 8, 9) Vi = 2.4V 2 pin 8 pins 7, 9 Vss V – 100 – 400 µA µA 10 µA COMPARATORS VCL Comparator Low Threshold Voltage (pin 10) VR = 5V Io = L I1 = H 66 78 90 mV VCM Comparator Medium Threshold Voltage (pin 10) VR = 5V Io = L I1 = H 236 251 266 mV VCH Comparator High Threshold Voltage (pin 10) VR = 5V Io = L I1 = H 396 416 436 mV ± 20 µA 35 µs 2 µs 100 µA IC Comparator Input Current (pin 10) toff Cutoff Time RT = 56kΩ C T = 820pF td Turn Off Delay (see fig. 2) Ioff Output Leakage Current (pins 1, 15) Io = H 25 I1 = H SOURCE DIODE-TRANSISTOR PAIR Vsat Vsat Saturation Voltage (pins 1, 15) Saturation Voltage (pins 1, 15) IM = – 0.5A (see fig. 2) Conduction Period Recirculation Period 1.7 1.1 2.1 1.35 IM = – 1A (see fig. 2) Conduction Period Recirculation Period 2.1 1.7 2.8 2.5 300 µA 1 1.3 1.25 1.7 V V 2 5 mA mA 1.35 2.3 V V 300 µA 1.5 2 V V ILK Leakage Current Vs = 46 V VF Diode Forward Voltage IM = – 0.5A IM = – 1A ISLK Substrate Leakage Current when Clamped IM = – 0.5A IM = – 1A V V SINK DIODE-TRANSISTOR PAIR Vsat Saturation Voltage (pins 1, 15) IM = 0.5A IM = 1A ILK Leakage Current Vs = 46V VF Diode Forward Voltage IM = 0.5A IM = 1A 4/11 1.1 1.6 1.1 1.4 PBL3717A Figure 1 : Test and Application Circuit Figure 2 : Waveforms with MA Regulating (phase = 0) 5/11 PBL3717A Figure 3 : Two Phase Bipolar Stepper Motor Driver Figure 4 : P.C. Board and Component Layout of the Circuit of fig. 3 (1 : 1 scale) 6/11 PBL3717A Figure 5 : Input and Output Sequences for Half Step and Full Step Operation APPLICATION INFORMATIONS Figure 3 shows a typical application in which two PBL3717A control a two phase bipolar stepper motor. Programming The logic inputs I0 and I1 set at three different levels the amplitude of the current flowing in the motor winding according to the truth table of page 2. A high level on the ”PHASE” logic input sets the direction of that current from output A to output B ; a low level from output B to output A. It is recommended that unused inputs are tied to pin 6 (Vss) or pin 4 (GND) as appropriate to avoid noise problem. The current levels can be varied continuously by changing the ref. voltage on pin 11. Control of the Motor The stepper motor can rotate in either directions according to the sequence of the input signals. It is possible to obtain a full step, a half step and a quarter step operation. Full Step Operation Both the windings of the stepper motor are energized all the time with the same current IMA = IMB. I0 andI1 remain fixed at whatever torque value is required. Calling A the condition with winding A energized in one direction and A in the other direction, the sequence for full step rotation is : AB → AB → AB → AB etc. For the rotation in the other direction the sequence must be reserved. In the full step operation the torque is constant each step. Half Step Operation Power is applied alternately to one winding then both according to the sequence : AB → B → AB → A → AB → B → AB → A etc. Like full step this can be done at any current level ; the torque is not constant but it is lower when only one winding is energized. A coil is turned off by setting I0 and I1 both high. 7/11 PBL3717A Quarter Step Operation It is preferable to realize the quarter step operation at full power otherwise the steps will be of very irregular size. The extra quarter steps are added to the half steps sequence by puttingone coil on half current according to the sequence. __ A A B AB → B → B → B → AB → A → A etc. 2 2 2 L -C Filter To reduce EMI and chopping losses in the motor a low pass L -C filter can be inserted across the outputs of the PBL3717A as shown on the followingpicture. Motor Selection As the PBL3717A provides constant current drive, with a switching operation, care must be takento select stepper motors with low hysteresis losses to prevent motor over heat. L≈ 1 LM 10 C≈ 4 ⋅ 10−10 L Figure 6 : Source Saturation Voltage versus Output Current (recircuit period) Figure 7 : Source Saturation Voltage versus Output Current (conduction period) Figure 8 : Sink Saturation Voltage versus Output Current Figure 9 : Comparator Threshold versus Junction Temperature 8/11 PBL3717A MOUNTING INSTRUCTIONS The Rth j-amb of the PBL 3717A can be reduced by soldering the GND pins to a suitable copper area of the printed circuit board or to an external heatsink. The diagram of fig. 11 shows the maximum dissipable power Ptot and the Rth j-amb as a function of the side ”α” of two equal square copper areas having a thichkness of 35µ (see fig. 10). Figure 10 : Example of P.C. Board Copper Area which is used as Heatsink Figure 11 : Max. Dissipable Power and JunctionAmbient Thermal Resistance versus size ”a” 9/11 PBL3717A POWERDIP16 PACKAGE MECHANICAL DATA mm DIM. MIN. a1 0.51 B 0.85 b b1 TYP. MAX. MIN. TYP. MAX. 0.020 1.40 0.033 0.50 0.38 0.055 0.020 0.50 D 0.015 0.020 20.0 0.787 E 8.80 0.346 e 2.54 0.100 e3 17.78 0.700 F 7.10 0.280 I 5.10 0.201 L Z 10/11 inch 3.30 0.130 1.27 0.050 PBL3717A 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. Specifications 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. 1994 SGS-THOMSON Microelectronics - All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands - Singapore Spain - Sweden - Switzerland - Taiwan - Thaliand - United Kingdom - U.S.A. 11/11