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PBL3717A
STEPPER MOTOR DRIVER
.FULL .BI .FROM .LOW .BUI .EXTERNALLY .OUTPUT .THERMAL
STEP - HALF STEP - QUARTER STEP OPERATING MODE POLAR OUTPUT CURRENT UP TO 1 A 10 V UP TO 46 V MOTOR SUPPLY VOLTAGE SATURATION VOLTAGE WITH INTEGRATED BOOTSTRAP LT IN FAST PROTECTION DIODES SELECTABLE CURRENT LEVEL CURRENT LEVEL DIGITALLY OR ANALOGUE CONTROLLED PROTECTION WITH SOFT INTERVENTION
Powerdip 12 + 2 + 2 (Plastic Package) ORDER CODE : PBL3717A
DESCRIPTION The PBL3717A is 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 three steps 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 external connection to 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 PBL3717A is supplied in a 12 + 2 + 2 lead Powerdip package.
July 2003
PIN CONNECTION (top view)
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PBL3717A
PIN FUNCTIONS
N 1 2 Name UTPUT B PULSE TIME Function Output Connection (with pin 15). The output stage is a "H" bridge formed by four transistors and four diodes suitable for switching applications. 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). 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. See pin 4. Supply Voltage Input for Logic Circuitry 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. 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. See INPUT 1 (pin 7) . 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 CT. 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). See pin 4. See pin 4. 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
3 4 5 6 7
SUPPLY VOLTAGE B GROUND GROUND LOGIC SUPPLY INPUT 1
8
PHASE
9 10
INPUT 0 COMPARATOR INPUT
11
REFERENCE
12 13 14 15 16
GROUND GROUND SUPPLY VOLTAGE A OUTPUT A SENSE RESISTOR
TRUTH TABLE
Input 0 (pin 9) H L H L Input 1 (pin 7) H H L L No Current Low Current Medium Current High Current
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PBL3717A
BLOCK DIAGRAM
ABSOLUTE MAXIMUM RATINGS
Symbol Vs Vss Vi Vc Vr Io Tstg Tj Power Supply Voltage Logic Supply Voltage Logic Input Voltage Comparator Input Reference Input Voltage Output Current (DC operation) Storage Temperature Operating Junction Temperature Parameter Value 50 7 6 Vss 15 1.2 - 55 to + 150 150 V A C C Unit V V V
THERMAL DATA
Symbol Rth j-case Rth j-amb Parameter Thermal Resistance Junction-pins Thermal Resistance Junction-ambient* Value 11 40 Unit C/W C/W
* Soldered on a 35 thick 20 cm2 P.C. board copper area.
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PBL3717A
ELECTRICAL CHARACTERISTICS (refer to the test circuit VS = 36V, VSS = 5V, Tamb = 25oC unless otherwise specified)
Symbol Vs Vss Iss IR Parameter Supply Voltage (pin 3, 14) Logic Supply Voltage (pin 6) Logic Supply Current (pin 6) Reference Input Current (pin 11) VR = 5V Test Conditions Min. 10 4.75 7 0.75 Typ. Max. 46 5.25 15 1 Unit V V mA mA
LOGIC INPUTS ViL ViH IiL IiH Input Low Voltage (pins 7, 8, 9) Input High Voltage (pin 7, 8, 9) Low Voltage Input Current (pins 7, 8, 9) High Voltage Input Current (pins 7, 8, 9) Vi = 0.4V Vi = 2.4V pin 8 pins 7, 9 2 0.8 Vss - 100 - 400 10 V V A A A
COMPARATORS VCL VCM VCH IC toff td Ioff Comparator Low Threshold Voltage (pin 10) Comparator Medium Threshold Voltage (pin 10) Comparator High Threshold Voltage (pin 10) Comparator Input Current (pin 10) Cutoff Time Turn Off Delay Output Leakage Current (pins 1, 15) RT = 56k CT = 820pF (see fig. 2) Io = H I1 = H 25 VR = 5V VR = 5V VR = 5V Io = L I1 = H Io = L I1 = H Io = L I1 = H 66 236 396 78 251 416 90 266 436 20 35 2 100 mV mV mV A s s A V 1.7 1.1 2.1 1.7 1 1.3 2.1 1.35 V 2.8 2.5 300 1.25 1.7 2 5 A V V mA mA
SOURCE DIODE-TRANSISTOR PAIR Vsat Saturation Voltage (pins 1, 15) IM = - 0.5A (see fig. 2) Conduction Period Recirculation Period IM = - 1A (see fig. 2) Conduction Period Recirculation Period Vs = 46 V IM = - 0.5A IM = - 1A IM = - 0.5A IM = - 1A
Vsat
Saturation Voltage (pins 1, 15)
ILK VF ISLK
Leakage Current Diode Forward Voltage Substrate Leakage Current when Clamped
SINK DIODE-TRANSISTOR PAIR Vsat ILK VF Saturation Voltage (pins 1, 15) Leakage Current Diode Forward Voltage IM = 0.5A IM = 1A Vs = 46V IM = 0.5A IM = 1A 1.1 1.4 1.1 1.6 1.35 2.3 300 1.5 2 V V A V V
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PBL3717A
Figure 1 : Test and Application Circuit
Figure 2 : Waveforms with MA Regulating (phase = 0)
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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)
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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 and I1 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.
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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 putting one coil on half current according to the sequence. _ _ A A B AB B B B AB A A etc. 2 2 2 Motor Selection As the PBL3717A provides constant current drive, with a switching operation, care must be taken to select stepper motors with low hysteresis losses to prevent motor over heat. Figure 6 : Source Saturation Voltage versus Output Current (recircuit period) Figure 7 : 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 following picture.
L
1 LM 10
C
4 10-10 L
Source Saturation Voltage versus Output Current (conduction period)
Figure 8 :
Sink Saturation Voltage versus Output Current
Figure 9 :
Comparator Threshold versus Junction Temperature
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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. Figure 10 : Example of P.C. Board Copper Area which is used as Heatsink The diagram of fig. 11 shows the maximum dissipable power Ptot and the Rth j-amb as a function of the side "" of two equal square copper areas having a thichkness of 35 (see fig. 10). Figure 11 : Max. Dissipable Power and JunctionAmbient Thermal Resistance versus size "a"
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PBL3717A
mm MIN. a1 B b b1 D E e e3 F I L Z 3.30 1.27 8.80 2.54 17.78 7.10 5.10 0.130 0.38 0.51 0.85 0.50 0.50 20.0 0.346 0.100 0.700 0.280 0.201 0.015 1.40 TYP. MAX. MIN. 0.020 0.033 0.020 0.020 0.787 0.055 inch TYP. MAX.
DIM.
OUTLINE AND MECHANICAL DATA
Powerdip 16
0.050
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PBL3717A
Information furnished is believed to be accurate and reliable. However, STMicroelectronics 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 STMicroelectronics. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics (c) 2003 STMicroelectronics - Printed in Italy - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia - Malta - Morocco Singapore - Spain - Sweden - Switzerland - United Kingdom - United States. http://www.st.com
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