MOTOROLA
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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
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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
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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
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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 F
6
4
Z5
4.7 V
2
R5
10 K
J1–8
R6
Bbot
1.0 K
T1
1.0 K
T1
+5.0 V
8
U3
9
11
12
U2
10
B+
270
B+
5
+
6 –
MC74HC02
C10
0.047 F
m
R25
150
Q14
MTB30P06V
D4
Q6
MMBT
A06LT1
D9
R29
R28
Btop
62
91
R41
1.96 K
1%
Q8
MMBT
A56LT1
+5.0 V
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 F
m
U3
4
4
Bin
6
MC74HC02
2
6
m
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 F
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
MC74HC02
7
Q13
MTB36N06V
D2
7
R27
820
9
Z4
4.7 V
Abot
150
Q7
MMBT
A06LT1
14
Aout
J2–2
D5
+5.0 V
8
Pa
R23
5
R26
4.3 K
Z9
12 V
+5.0 V
J1–12
Aout
T2
GND
11
10
U3
Ain
270
13
Z3
4.7 V
R8
Btop
Bout
R39
37.4 K
1%
R22
U2
12
R7
10 K
J1–6
Bin
6
VCC
3
MC74HC02
+5.0 V
U4
MC34152
m
4
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
C1 1.02 K
0.001
R13
1.02 K
CS+
R36
0.01
W
CS–
GND
4
MOTOROLA
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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
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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
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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
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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
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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.
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NOTES
10
MOTOROLA
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NOTES
MOTOROLA
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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
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