MOTOROLA Order this document by AN1607/D SEMICONDUCTOR APPLICATION NOTE AN1607 ITC122 Low Voltage Micro to Motor Interface By Bill Lucas and Warren Schultz A MOSFET power stage that is designed to run Brush or Brushless DC motors with input signals from an ASB124 Motion Control Development Board is presented here. It will supply up to 4 amps continuous current from DC bus voltages up to 48 volts. Figure 1. ITC122 — Low Voltage Micro to Motor Interface EVALUATION BOARD DESCRIPTION A summary of the information required to use ITC122 Low Voltage Micro to Motor Interface boards is presented as follows. A discussion of the design appears under the heading Design Considerations. Function The evaluation board shown in Figure 1 is designed to provide a direct interface between microcomputers and fractional horsepower motors. It accepts 6 logic inputs which control 3 complementary Half–Bridge outputs, and is arranged such that a logic ZERO at the input turns on the corresponding power transistor. This type of configuration is applicable to pulse width modulated (PWM) systems where the PWM signal is generated in a microcomputer, digital signal processor, or other digital system. It is suitable for driving fractional horsepower Brush and Brushless DC motors. In addition to controlling the motor, current sense, temperature sense, and bus voltage feedback are provided. This board is designed to interface directly with Motorola ASB124 motor control development boards. REV 1 MOTOROLA Motorola, Inc. 1998 1 AN1607 Coupled with an ASB124 control board, it completes the link between software development tools and a motor. Its use allows code to be written before hardware design is completed in an environment where mechanical outputs can be seen. The design can also be used as a reference for speeding hardware development. Electrical Characteristics The following electrical characteristics apply to operation at 25 degrees Celsius, and unless otherwise specified, B+ = 24 volts. Table 1. Electrical Characteristics Characteristic Symbol Min Power Supply Voltage B+ 12 RMS Motor Current — Two Phases Active — Three Phases Active IM Typ Max Units 48 Volts 4 5 Amps Amps Input Current @ VIN = 5 V Iin 500 µA Min Logic 1 Input Voltage VIH 2.7 Volts Max Logic 0 Input Voltage VIL 2.0 Volts Quiescent Current ICC 25 mA Bus Current Sense Voltage Isense 250 mV/A Temperature Sense Voltage Vtemp .65 Volts Bus Voltage Sense Voltage Vbus 50 mV/V Power Dissipation — Two Phases Active — Three Phases Active PDISS 5.5 6.75 Watts Watts The above numbers for power dissipation assume still air and no additional heat sinking. Maximum current ratings are based upon applying pulse width modulation signals only to the top inputs, a maximum PWM frequency of 23 KHz, and a 2 maximum supply voltage of 40 volts. Bonding heat sinks to the back of the board and/or providing air flow will significantly increase both power dissipation and output current ratings. MOTOROLA AN1607 Content Board contents are described by the following schematic and parts list. A pin by pin circuit description follows in the next section. Table 2. Parts List Designators Qty. Description Rating Manufacturer Part Number C11, C2–C4, C8, C9 6 1 µF Capacitor 25 V Digi–Key PCS5105CT–ND C5 1 .1 µF Capacitor 50 V Digi–Key PCC104BCT–ND C6 1 220 µF 63 V Digi–Key P6736–ND C7, C10 2 .1 µF Capacitor 100 V Sprague 1C105Z5U104M100B C1 1 .001 µF Capacitor 50 V Sprague PCC102CCT–ND D1 1 LED SOT–23 Digi–Key LT–1076–ND D2–D10 9 Schottky Diode SOD–123 40 V Motorola MBR0540T1 D11 1 SOD–123 Diode 30 V Motorola MMSD1000T1 J1 1 2x7 .1o.c. Jumper Block Note: 2 Digi–Key S2011–36–ND J2 1 2x8 .1o.c. Jumper Block Note: 2 Digi–Key S2011–36–ND Q13, Q15, Q17 3 N–Channel Power TMOS FET Motorola MTB36N06V Q12, Q14, Q16 3 P–Channel Power TMOS FET Motorola MTB30P06V Q3, Q4, Q6, Q7, Q9, Q10 6 Small Signal NPN Transistor Motorola MMBTA06LT1 Q5, Q8, Q11 3 Small Signal PNP Transistor Motorola MMBTA56LT1 Q1, Q2 2 Small Signal NPN Transistor Motorola BCP56T1 R36 1 .01 Ohm Resistor 1% OHMITE RW1S5CAR010F R13, R45 2 1.02K Ohm Resistor 1% R15, R16 2 4.7K Resistor R17 1 1.8K Resistor Yageo R37–R39, R43 4 37.4K Ohm Resistor 1% Yageo R40–R42, R44 4 1.96K Ohm Resistor 1% Yageo R14 1 24.3K Ohm Resistor 1% Yageo R2, R4, R6, R8, R10, R12 6 1K Resistor Yageo R1, R3, R5, R7, R9, R11 6 10K Resistor Yageo R19, R27, R31 3 820 Ohm Resistor Yageo R18, R26, R30 3 4.3K Resistor Yageo R20, R29, R33 3 56 Ohm Resistor Yageo R21, R28, R32 3 91 Ohm Resistor Yageo R22, R24, R34 3 270 Ohm Resistor Yageo R23, R25, R35 3 150 Ohm Resistor Yageo T1 1 7 Screw Terminal Connector Phoenix Contact MKDSN 1,5/7–5,08 T2 1 6 Screw Terminal Connector Phoenix Contact MKDSN 1,5/6–5,08 U1 1 5 Volt Regulator Motorola MC78L05ACD U2, U3 2 Quad NAND Gate Motorola MC74HC02D U4, U5 2 MOSFET Driver Motorola MC34152D U6 1 Dual Rail to Rail Op–Amp Motorola MC33202D Z1–Z6 6 Zener Diode SOT–23 4.7 V Motorola BZX84C4Z7LT1 Z7 1 Zener Diode SMB 15 V Motorola P6SMB15AT3 Z8–Z10 3 Zener Diode SOD–123 12 V Motorola MMSZ5242BT1 No Designator 4 Self Stick Rubber Feet ITC122 1 Printed Circuit Board MOTOROLA 1.5 Watt Yageo 1 Watt Yageo 3 AN1607 B+ +5.0 V R11 10 K J1–2 R12 Atop 1.0 K T1 U2 2 3 Q3 MMBT A06LT1 Z6 4.7 V R19 820 +5.0 V R9 10 K J1–4 Abot R10 T1 1.0 K +5.0 V MC74HC02 + C8 1.0 mF 4 6 4 Z5 4.7 V 2 R5 10 K J1–8 Bbot R6 T1 1.0 K 1.0 K T1 +5.0 V 8 U3 9 11 12 U2 B+ 270 B+ Q6 MMBT A06LT1 150 D9 + 6 – MC74HC02 Q14 MTB30P06V R29 R28 Btop 62 91 R41 1.96 K 1% Q8 MMBT A56LT1 +5.0 V 5 C10 0.047 mF R25 D4 MC74HC02 7 T2 AGND 7 J2–4 R4 1.0 K T1 3 14 2 R31 820 7 +5.0 V + R2 1.0 K Z1 4.7 V 5 C9 1.0 mF U3 4 4 Bin 6 MC74HC02 2 6 62 R32 Ctop 91 VCC Ain Aout GND 5 D6 R35 MC33202 I SENSE J2–15 150 +5.0 V 1 8 3 + – 2 U6 4 GND T1 Figure 2. Schematic T2 Cout Cbot D7 7 3 Q16 MTB30P06V J2–6 R34 270 Bout R37 37.4 K 1% Pc AGND U5 MC34152 VCC R40 1.96 K 1% Q11 MMBT A56LT1 C12 0.047 mF D10 R33 Q9 MMBT A06LT1 Q10 MMBT A06LT1 MC74HC02 U3 1 Z2 4.7 V R1 10 K R30 4.3 K Z10 12 V +5.0 V Bout Bbot Pb MC33202 U6 Q15 MTB36N06V R38 37.4 K 1% B+ R3 10 K Ctop T1 R24 13 J1–10 Cbot D3 R27 820 10 Q13 MTB36N06V 150 Q7 MMBT A06LT1 9 Z4 4.7 V R23 D2 7 R26 4.3 K Z9 12 V 14 Aout GND +5.0 V 8 Pa Abot D5 +5.0 V J1–12 Aout 270 13 10 U3 Ain 11 Z3 4.7 V R8 Btop Bout T2 J2–2 U2 12 R7 10 K J1–6 Bin R39 37.4 K 1% R22 5 3 MC74HC02 +5.0 V U4 MC34152 6 VCC Atop R42 91 1.96 K 1% AGND U2 5 R21 Q5 MMBT A56LT1 VCC 62 D8 Q4 MMBT A06LT1 1 Q12 MTB30P06V R20 R18 4.3 K Z8 12 V MC74HC02 R14 24.3 K Q17 MTB36N06V R45 CS+ C1 1.02 K 0.001 R13 R36 0.01 W 1.02 K CS– GND 4 MOTOROLA AN1607 B+ B+ R15 4.7 K R16 4.7 K Q1 BCP56T1 Q2 BCP56T1 VCC Z7 15 V + C3 1.0 mF U1 MC78L05ACD 8 + C2 1.0 mF R17 1.8 K D1 IN OUT GROUND GND 6, 7 R43 37.4 K 1% +5.0 V Vbus + 1 C6 220 mF + C4 1.0 mF T2 C5 C11 0.1 mF 1.0 mF C7 0.1 mF R44 1.96 K 1% J2–13 AGND GND T1 GND T2 J1–5, 7, 9, 11, 13, 14 J2–1, 3, 5, 7, 8, 9, 10, 11 J2–14, 16 AGND Vtemp J2–12 D11 AGND AGND Figure 3. Schematic MOTOROLA 5 AN1607 Pin By Pin Description Inputs and outputs are grouped into four connectors. Two connectors are provided for inputs, one with screw terminals and the other for ribbon cable. Either can be used, they are wired in parallel. Outputs to the motor, B+, and ground are also supplied on a screw connector. Feedback signals are grouped together on a separate ribbon cable connector. In addition, through–hole pads have been placed immediately adjacent to R36 and D11 for easy access to the current feedback resistor and temperature sensing diode. Ribbon connector PINOUTS are shown in Figure 4. FEEDBACK INPUT +5 1 2 Atop GND 1 2 Pa +5 3 4 Abot GND 3 4 Pb GND 5 6 Btop GND 5 6 Pc GND 7 8 Bbot GND 7 8 N/C GND 9 10 Ctop GND 9 10 N/C GND 11 12 Cbot GND 11 12 Vtemp GND 13 14 GND Vbus 13 14 AGND I SENSE 15 16 AGND J1 J2 TOP VIEW Figure 4. Connector Pinouts Inputs: Inputs Atop, Abot, Btop, Bbot, Ctop, and Cbot are logic inputs. A logic 0 turns on the input’s corresponding output transistor, i.e., a logic 0 on Atop turns on output transistor Atop, etc. Logic levels are standard 5 volt CMOS. Input current is higher, typically 500 µA, since each of these inputs is pulled up with a 10K resistor. In the absence of any inputs all output transistors are turned off. If a logic 0 is inadvertently applied to both top and bottom inputs for one phase, i.e., Atop & Abot, the bottom input is locked out and only the top output transistor is turned on. This feature helps protect the bridge from errors that may occur during code development. Motor Outputs: Motor output terminals are labeled Aout, Bout, and Cout. This output configuration can be used to drive a fractional horsepower 3 phase brushless DC motor, a reversible brush DC motor, or 3 brush DC motors unidirectionally. When driving a single brush DC motor, thermal performance is optimized by using Aout and Cout for the motor connections. B+: B+ is the motor power input connection. It is the only supply required. Acceptable input voltage range is 12.0 to 48 VDC. It is located on the output connector. 6 GND: There are multiple ground connections. One of the two grounds on the output connector should be used as the power supply return. Isense: Isense is a current sense feedback voltage that appears on pin 15 of connector J2. It is derived from a .01 ohm low inductance surface mount sense resistor that is in series with the ground return. The voltage across this resistor is amplified with a gain of 25. Isense, therefore, represents motor current with a scale factor of 250 mV/Amp. Since only return current is measured, this output will not detect shorts from the motor outputs to ground. Vbus: Vbus is a bus voltage feedback signal that appears on pin 13 of connector J2. It is derived from a 37.4K/1.96K divider which scales B+ at a ratio of approximately 50 mV per volt. This is an unfiltered and unbuffered signal. Vtemp: A temperature output signal derived from a forward biased diode’s VF appears on connector J2 at pin 12. The diode, D11, is mounted such that it measures board temperature adjacent to power transistor Q12. MOTOROLA AN1607 Phase Voltage Feedback: Phase voltage feedback signals Pa, Pb, & Pc are also included on feedback connector J2. They are located on pins 2, 4, and 6. These pins provide motor phase voltages divided down with the same 50 mV/Volt ratio as Vbus. They are also unfiltered and unbuffered signals. APPLICATION EXAMPLE connections to an ASB124 control board and a Brushless DC motor. This arrangement can be run stand alone, or the ASB124 can be connected to an MMDS05 for code development. The two boards are designed such that the Drive and Feedback ribbon connectors line up. Ribbon cables are supplied with the ASB124 board. Once they are plugged in it is only a matter of connecting power supply, motor, and Hall sensor leads to get a system up and running. An application example shown in Figure 5 illustrates system MOTION CONTROL DEVELOPMENT BOARD LOW VOLTAGE MICRO TO MOTOR INTERFACE GND 7.5–28 VDC B+ BRUSHLESS MOTOR MOTOROLA ASB124 MOTOROLA ITC122 Aout Bout Cout DRIVE B+ GND 12–48 VDC GND +5 GND HALL3 HALL2 HALL1 FEEDBACK Figure 5. Application Example An important application’s consideration is pulse width modulation topology. The controller that is shown in Figure 5 pulse width modulates Atop, Btop, & Ctop inputs, and commutates Abot, Bbot, & Cbot. This configuration performs better from a power dissipation standpoint than its more commonly used alternative, namely lower half bridge pulse width modulation with upper half bridge commutation. When the upper half bridge is pulse width modulated, circulating currents flow through the lower rds(on) and lower forward diode voltages of the N–Channel transistors. Since transition times for both P–Channel & N–Channel transistors are approximately the same, high side pulse width modulation is considerably more efficient. With more efficient operation, available output power to the motor is maximized. DESIGN CONSIDERATIONS A block diagram that provides an overview of the design is MOTOROLA illustrated in Figure 6. Top and Bottom inputs for each phase are coupled to gate drive circuits through cross coupled NOR gates. This arrangement locks out the bottom input when both inputs for one phase are low, thereby adding robustness for lab use. If all six inputs are low, transistors Atop, Btop, and Ctop are turned on, which brakes the motor. This condition can occur when an ASB124 controller is powered down. The output is a 3 phase bridge that is made from complimentary 30 amp surface mount MOSFET’s. Gate drive for the N–Channel transistors is provided by MC33152 MOSFET drivers and for the P–Channels by a discrete circuit. A more detailed view of the gate drive circuits is shown in Figure 7. Both the P–Channel & N–Channel transistors have transition times targeted for approximately 200 nsec. This target allows high enough value gate drive resistors to somewhat soften diode snap, yet produces switching losses that are less than static losses at 23 KHz. 7 AN1607 Atop B+ (12–48 VOLTS) Atop Btop Btop Ctop Ctop Aout Bout Abot Abot Cout Bbot Bbot Cbot Cbot GND Figure 6. Block Diagram 8 MOTOROLA AN1607 B+ 5.6 K 12 V 62 91 820 Aout 270 MC34152 150 Figure 7. Gate Drive CONCLUSION The ITC122 Low Voltage Micro to Motor Interface is part of a motor control tool set that significantly reduces design and MOTOROLA development time. It accepts signals from an ASB124 Motion Control Development Board, and provides a 3 phase power output that is capable of supplying 4 amps from bus voltages up to 48 VDC. 9 AN1607 NOTES 10 MOTOROLA AN1607 NOTES MOTOROLA 11 AN1607 Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters which may be provided in Motorola data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. 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