AN970

AN970
Using the PIC18F2431 for Sensorless BLDC Motor Control
Author:
Padmaraja Yedamale
Microchip Technology Inc.
INTRODUCTION
Brushless Direct Current (BLDC) motors have many
advantages over other types of motors available in the
industry. Previously, we have discussed the working
principles of BLDC motors and the basics of their
control in Microchip application note AN885, Brushless
DC (BLDC) Motor Fundamentals. We have also
discussed the use of PIC18FXX31 devices to control a
BLDC motor in both open loop and in closed loop using
Hall effect sensors and quadrature encoders
(Microchip application note AN899, Brushless DC
Motor Control Using PIC18FXX31 Microcontrollers).
This application note describes BLDC motor speed
control without the use of sensors.
Those readers interested in additional applications
may refer to Microchip application notes AN857, Brushless DC Motor Control Made Easy and AN901, Using
the dsPIC30F for Sensorless BLDC Control, to learn
how other PICmicro® microcontrollers and dsPIC®
digital signal controllers can be used for BLDC motor
control.
ADVANTAGES AND
DISADVANTAGES OF SENSORLESS
CONTROL
Sensorless control of a BLDC motor calls for
commutation based on the Back Electromotive Force
(BEMF) produced in the stator windings. Sensorless
control has two distinct advantages: lower system cost
and increased reliability.
Hall effect sensors are not required for sensorless
control. Some motors may have the Hall sensor
magnets mounted on the rotor, in addition to the main
rotor magnets. These are used to simplify the process
of mounting the Hall sensors onto the stator. The
sensor magnets are a scaled-down replica of the rotor;
whenever the rotor rotates, they produce the same
effect as the main magnets. The Hall sensors are
normally mounted on a PC board and are fixed to the
enclosure cap on the non-driving end of the motor.
© 2005 Microchip Technology Inc.
With a sensorless method of commutation, the Hall
sensors, the sensor magnets, the sensor wires and the
PC board can be eliminated. This simplifies the motor
construction and reduces cost. Inherently, systems with
fewer components are more reliable. Applications like
the compressor control in a refrigerator or in HVAC
systems, which generates heat and an elevated
temperature, may accelerate Hall sensor failures.
Using sensorless control improves the reliability of total
system.
There are two disadvantages to sensorless control:
• The motor must be moving at a minimum rate to
generate sufficient BEMF to be sensed.
• Abrupt changes to the motor load can cause the
BEMF drive loop to go out of lock.
As the BEMF signal is proportional to the speed of
rotation at standstill and at low speeds, the amplitude
of the BEMF poses a challenge to determine the zero
crossover point. In order to overcome this problem, the
motor is normally run in open loop during starting and
is accelerated to a speed where the BEMF has
sufficient amplitude to detect and then synchronize with
the zero crossing point. Running the motor in open loop
makes it difficult to know the rotor position, when
starting from standstill. So, the rotor can rotate in either
direction when energized.
Applications which require very low motor speed may
be forced to use sensors for control. There are many
applications in appliances, automotive, and industrial
applications where very low speed is not an issue, and
the motor needs variable speeds of about 25% of the
rated speed. Sensorless control is ideal for such applications.
Another requirement is that the sensorless control
needs extra resources on the control circuit side.
Depending upon the method used, it may require a fast
A/D converter on the microcontroller, or comparator
and filter circuits.
DS00970A-page 1
AN970
THEORY OF OPERATION
HALL SENSOR SIGNALS VS. BEMF
When a BLDC motor rotates, each winding generates
BEMF which opposes the main voltage supplied to the
windings according to Lenz’s Law. The polarity of this
BEMF is in the opposite direction of the energizing voltage. BEMF can be calculated as shown in Equation 1,
and depends mainly on three factors:
Figure 1 shows the relationship between the Hall
sensor signals and the BEMF signals. Hall sensor
signals are out of phase by 120 degrees to each other.
At every 60 degrees, one of the Hall sensors makes a
transition.
• Angular velocity of the rotor
• Magnetic field generated by rotor magnets
• The number of turns in the stator windings
EQUATION 1:
Back EMF = NlrBω
where
N = number of winding turns per phase
l = the length of the rotor
r = the internal radius of the rotor
B = the rotor magnetic field density
ω
= the motor angular velocity
Once the motor is designed, the rotor’s magnetic field
and the number of turns in the stator windings remain
constant. The only factor that governs back EMF is the
angular velocity or speed of the rotor; as the speed
increases, back EMF also increases. The motor technical specification gives a parameter called the back
EMF constant, which can be used to estimate BEMF
for a given speed.
DS00970A-page 2
The BEMF generated in the windings are also at 120
degrees out of phase to each other, but they are
asynchronous with the Hall sensor signals. In every
energizing sequence, two phases are connected
across the power supply and the third winding is left
open. The BEMF voltage is monitored on the winding
that is left open. With this, the BEMF voltage in
windings increases when it is connected to power
supply and reduces when it is connected to the return
path. The transition takes place when the winding is left
open in the sequence. The combination of all 3 zero
cross over points are used to generate energizing
sequence. The phase difference between the hall
sensor and the BEMF signal is 30 degrees. This is in
the firmware.
Another aspect to be considered is very low-speed
operation. Because BEMF is proportional to the
rotation speed, it would be at a very low amplitude at
very low speeds, making it difficult to detect the zero
crossover. In addition, since the commutation itself is
derived based on BEMF zero crossovers, it is impossible to start the motor from standstill. To overcome this
difficulty, the motor has to be started from standstill in
open loop. When sufficient BEMF is built to detect the
zero crossover point, control is shifted to the BEMF
sensing. The minimum speed at which the BEMF can
be sensed is calculated from the BEMF constant of the
motor.
© 2005 Microchip Technology Inc.
AN970
FIGURE 1:
WAVEFORM OF HALL SENSOR VERSUS BEMF VOLTAGES
60°
Hall A
Hall B
Hall C
Phase A
Zero cross
Phase A
Current
Phase A
Phase A
Voltage
Phase B
Zero cross
Phase B
Current
Phase B
Phase B
Voltage
Phase C
Zero cross
Phase C
Current
Phase C
Phase C
Voltage
BEMF ZERO CROSSOVER SENSING
METHODS
FIGURE 2:
BEMF voltage zero crossing can be detected by
different methods. This section gives three different
methods of detecting BEMF zero cross point.
The first method is comparing the back EMF voltage to
half of the DC bus voltage by using comparators.
Figure 2 shows this method. Phase A is connected to
the positive side of the power supply (DC+), Phase C is
connected to the negative side (or return path DC) of
the power supply and Phase B is open. When BEMF is
observed on Phase B, it increases and decreases as
the power supply (DC+ and DC-) are connected and
disconnected to the winding terminals in the energizing
sequence. By comparing the BEMF voltage to half of
the DC bus, it gives a voltage at the central point of
phase A and phase C.
BEMF VOLTAGE
COMPARED TO HALF OF
DC BUS
DC+
A
Back EMF
DC- C
B
+
To IC2
_
DC/2
Each phase requires a circuit like that shown in
Figure 2 for Phase B. Combinations of these three
signals are used to derive the commutation sequence.
This scheme is easy to implement with three op amp
comparators.
© 2005 Microchip Technology Inc.
DS00970A-page 3
AN970
There are a few drawbacks to this circuit. First, if all
three windings do not have identical characteristics, the
BEMF measured will have either positive or negative
phase shift. This will result in energizing windings at
different instances than they should be. This may result
in the motor winding drawing excessive current.
Another drawback is that if the motor rated voltage is
much less than the DC bus voltage, there could be a
large difference between the BEMF zero crossover
point and half of the DC bus voltage. This could also
result in having a phase shift result in either direction.
The circuit can be improved upon by generating a
virtual neutral point, as shown in Figure 3. The neutral
point is generated using a resistor network. Three
networks are connected in parallel with the motor
windings and connected together to generate a virtual
neutral point. This resistive network is assembled on
the control board between the 3-phase inverter bridge
and the motor terminals. The resistor values should be
chosen such that they will have insignificant effect on
the motor current. (Refer to Appendix A: “Motor
Control Circuit Schematics” for the circuit schematic
used in this application note.) In this case, the BEMF
signal is compared with this virtual neutral point. When
the BEMF developed in the winding crosses the zero
point towards positive side, the comparator output
makes a transition from low-to-high. When the BEMF
developed in the winding crosses the zero point
towards negative side, the comparator output makes a
transition from high-to-low. By having three such
comparator circuits, one on each of the phases gives
three digital signals corresponding to the BEMF signal
in the windings. The combination of these three signals
is used to derive the commutation sequence.
FIGURE 3:
BEMF VOLTAGE
COMPARED TO A VIRTUAL
NEUTRAL POINT
A third method of detecting the BEMF zero crossover is
using the A/D converter channels, as shown in
Figure 4. The PIC18FXX31 microcontrollers have a
high-speed A/D converter that can be used for this
purpose. Using a potential divider, the BEMF signal is
brought down to a level that the microcontroller can
measure. This signal is sampled by the A/D, and is
continuously compared with a digital value
corresponding to the zero point. When the two values
match, the commutation sequence is updated. The
advantage with this method is that it is more flexible in
terms of measurement. When the speed varies, the
winding characteristics may fluctuate, resulting in
variation of BEMF. In such situations, the microcontroller has complete control over the determination of
the zero crossover point. Also, digital filters can be
implemented to filter out the high-frequency switching
noise components from the BEMF signal.
FIGURE 4:
BEMF VOLTAGE
MEASURED USING
ANALOG-TO-DIGITAL
CONVERTERS
A
C
B
Signal conditioning
AN0
A
AN1
AN2
Back EMF
Back EMF
C
DC-
B
+
_
Virtual
Neutral
DS00970A-page 4
To IC2
© 2005 Microchip Technology Inc.
AN970
HARDWARE
Note:
Figure 5 shows the block diagram for the sensorless
BLDC control system discussed here; a complete schematic of the prototype board is provided in Appendix A:
“Motor Control Circuit Schematics”. The board is
capable of using either the PIC18F2331/2431 Microcontroller or a dsPIC30F2010 digital signal controller (only
the PIC18F2431 is discussed here). Toggle switch S2 is
used for changing the rotational direction and switch S1
is used for changing the state between run and stop. A
potentiometer (R14) is used to set the speed reference;
it is connected to A/D converter channel AN1.
BEMF Sensing Circuit
In this application note, we are following the second
method of determining the BEMF zero cross detection
shown in Figure 3. As shown in the schematics in the
Appendix, low-pass filter circuits and potential divider
circuits are implemented on all three motor terminals.
The low-pass filter is necessary to filter out the high
frequency noise that is generated by the high frequency
PWM switching. The potential divider reduces the
voltage from high motor voltage to the level MCU can
measure. After this, the BEMF signals are connected
together using R27, R30 and R40 to form a virtual
neutral point. The BEMF signal from each phase is compared with this neutral point using the op amp
comparators. In order to use this configuration, jumpers
J7, J11 and J13 should be bridged across pins 1 and 2,
and jumpers J8, J12 and J14 should be bridged. By
doing this, the comparator outputs are connected to the
input capture pins IC1, IC2 and IC3 on the PIC18FXX31.
Shunt resistor R26 is connected in the return path of the
DC bus. The voltage drop across this resistor varies
linearly with respect to motor current. This voltage is
amplified by a 1:10 ratio using op amp circuit U10A. This
amplified voltage (motor current) is measured using A/D
channel AN0. The motor current is compared with a
current limit set by another potentiometer (R60). If the
motor current exceeds the limit set, the output of U7D
will toggle, indicating an overcurrent fault. This Fault is
connected to Fault A input pin on PIC18F2431, which is
an active-low pin.
The board also provides the option for connecting the
BEMF signals to the A/D channels. The BEMF signal is
filtered using the low-pass filters comprised of R34/C17,
R41/C19 and R49/C19 on motor terminals M3, M2 and
M1, respectively. The potential divider circuits comprised
of R34/R36, R41/R44 and R49/R52 on motor terminals
M3, M2 and M1 reduce the BEMF voltage to TTL level.
To route the BEMF signals to the A/D channels, J7, J11
and J13 should be bridged between pins 2 and 3.
A switched-mode block power supply is used to generate 24V (shown in bold lines in Figure 5) from an AC
input. Using linear voltage regulators VR1 and VR2, +5V
and +15V are generated, respectively. The former powers the microcontroller, all op amps and related logic
circuits, while the latter is used to power the MOSFET
drivers (U6, U8 and U9).
FIGURE 5:
MOTOR CONTROL HARDWARE BLOCK DIAGRAM
+15V
Regulator
+5V
Regulator
Motor
Speed
+5V
IC1
IC2
IC3
RA2
RA3
RA4
S2
S3
RC5
24V
Power Supply
+24V
PWM5
PWM5
PWM4
PWM4
PWM3
PWM3
PWM2
PWM1
RC4
PIC18F2431
PWM2
IGBT
Driver
PWM1
PWM0
PWM0
3-phase
Inverter
Bridge
BLDC
Motor
AN0
RS232
AC input
+15V
AN1
ICD2
For a complete list of motor control
application
notes
refer
to
www.microchip.com/motor.
Back EMF
Signals
FLTA
Amplifier
Comparator
Imotor
Current
Shunt
Signal
Conditioning
IC1
IC2
IC3
Overcurrent Limit
© 2005 Microchip Technology Inc.
DS00970A-page 5
AN970
Motor Specifications
A Hurst NT dynamo Brushless DC motor is used for the
experiments. Its specifications are:
•
•
•
•
Rated voltage: 24 VDC
Rated current: 1.00 A
Rated speed: 2500 RPM
Rotor poles: 10 (5 pole pairs)
Software Routines
As discussed in earlier sections, the motor has to be
run in open loop during start-up. When the speed
reaches a level where the BEMF voltage has sufficient
amplitude to measure the zero crossover point, the
control is switched to closed loop. The difficult portion
is synchronizing the rotor from open loop to closed loop
with BEMF zero cross signals.
at one fixed speed. The Timer1 reload value, as shown
in Equation 2, depends upon the motor rated speed,
number of rotor poles, and the Timer1 prescaler value.
EQUATION 2:
Timer1 Time =
60
RPM x Pole pairs x 6
According to Equation 2, in order to run the motor at
400 RPM, Timer1 should expire every 5 ms, or 2.2 ms
for 900 RPM. The Timer1 overflow value can be
calculated based on the main oscillator frequency and
Timer1 prescaler, as shown in Equation 3.
EQUATION 3:
Fosc
Timer1 Reload Value = FFFFh – ⎛ Timer1 time x -----------⎞
⎝
4 ⎠
Motor Start-up
From experimentation, it has been determined that the
motor develops sufficient BEMF voltage amplitude at
about 900 RPM. At this speed, the BEMF signals are
compared with the virtual neutral point; this signal is
read using the Input Capture module. This is done in
two steps: when the motor is run at approximately
400 RPM, and then accelerated to 900 RPM.
Timer1 is used to time the energizing sequence. The
Timer1 reload value is calculated and the new energizing sequence is output on the PWM pins when the
reload value expires. This ensures that the motor runs
FIGURE 6:
DS00970A-page 6
Upon a Timer1 overflow in the ISR, a new energizing
sequence is loaded into the PWM override registers
and Timer1 registers are reloaded with the value
calculated using Equation 3. The PWM duty cycle
corresponding to the speed is calculated and loaded on
to the PDC registers. When the motor starts running at
900 RPM, the BEMF zero crossover point signals from
the comparators are observed for 16 cycles to
synchronize with the energizing sequence.
OSCILLOSCOPE WAVEFORM OF BEMF AND HALL SENSOR SIGNALS
© 2005 Microchip Technology Inc.
AN970
FIGURE 7:
BEMF VERSUS ZERO CROSSING
a) Back EMF signal vs. zero crossover point (without filter)
b) Back EMF signal vs. zero crossover point (with filter)
© 2005 Microchip Technology Inc.
DS00970A-page 7
AN970
SYNCHRONIZING ZERO
CROSSOVER SIGNALS WITH THE
ENERGIZING SEQUENCE
When the motor is running at 900 RPM, the BEMF zero
crossover (BEMC-ZC) signals, with respect to Hall
sensor output, looks like those shown in Figure 6. The
phase difference between the actual BEMF-ZC and the
Hall sensors is 30 degrees. From the experiments, its
found that the delay between the Hall signals to
BEMF-ZC signals connected to input capture pins is 60
degrees throughout the speed range. Keeping this
delay in mind, the energizing sequence has to be
synchronized with the BEMF-ZC signal. Timer1 is used
FIGURE 8:
to count a 60-degree electrical delay from every
BEMF-ZC signal. After the timer expires, the energizing
sequence is loaded to the OVDCOND register.
In this version of firmware, IC1 input is used for
synchronizing the BEMF-ZC signals twice in an electric
cycle. All three input capture inputs are used for
determining the energizing sequence for every rotor
state.
The Motion Feedback Module (MFM) on the
PIC18F2431 has programmable digital filters. These
act like low-pass filters with a selectable prescaler.
Based on the speed, three levels of filtering is provided
in this firmware.
A more detailed overview of the firmware is provided in
the flowcharts in Figure 8 through Figure 10.
MAIN MOTOR CONTROL SOFTWARE LOOP
START
No
S2 or S3
pressed?
Yes
Initialize PWM in Independent mode
Initialize ADC
No
Is Sensorless
on?
Yes
Update PWM Duty Cycle Routine
DS00970A-page 8
PWM Duty Cycle Calculation
Add Offset to the Speed
Reference
Limit Speed Ref Value to
FDh
PWM Duty cycle =
[(MotorVoltage/ DCBusVoltage)
X (4 X PWMPeriod)]
X [SpeedRef/255]
Check S2/S3 Activity Routine
Load PWM Duty Cycle to all
PDC<H:L> Registers
Check Overcurrent Routine
RETURN
© 2005 Microchip Technology Inc.
AN970
FIGURE 9:
ISR FLOWCHART (MAIN ROUTINE AND IC1 SERVICE)
Main ISR Service Routine (ISR_HIGH)
IC1 ISR?
Yes
A
No
Timer1 ISR?
Yes
B
No
Read Motor Current from AD0
ADC ISR?
Yes
No
Read Speed Ref from AD1
IC1 Service Routine
PWM ISR?
Yes
C
A
No
RETFIE
No
Is openloop
speed >
Min_speed?
Yes
Observe BEMF-ZC
for 16 Cycles
No
Is
Sensorless on?
Yes
No
Is
BEMF > 16
counts?
Set DFLTCON
Clock Divide Value
Based on Speed
Yes
Load 60 Degree Time to Timer
Set Digital Filter
to Low Clock Divide Ratio
Enable Timer1 Interrupt
RETFIE
© 2005 Microchip Technology Inc.
DS00970A-page 9
AN970
FIGURE 10:
ISR ROUTINE (TIMER1 AND PWM SERVICE)
Timer1 Service Routine
B
Is
Sensorless on?
No
Is the speed
in open loop
step1?
No
Update the Switching Sequence
Based on the IC1/IC2/IC3 State
Load 60 Degree Time to Timer1
No
Yes
Yes
Yes
Is the speed
in open loop
step2?
Reload
TMR1<H:L> = HIGH_OL_SPEED
Reload
TMR1<H:L> = LOW_OL_SPEED
Set the Energizing Sequence
with Count 1 to 6
RETFIE
PWM Service Routine
C
Is the rotor
locked up?
Yes
All PWMs to Inactive State
No
Is there a
overcurrent (OC)
fault?
No
Yes
Is OC >
MAX FAULTA_COUNT
in 256 PWM
cycles?
Yes
Configure FAULTA
to Catastrophic mode
No
Blink LED1 Indicating OC
RETFIE
DS00970A-page 10
© 2005 Microchip Technology Inc.
AN970
RESOURCE USAGE
The BLDC application consumes CPU resources as
shown in Table 1.
TABLE 1:
RESOURCES USED IN THE
BLDC (USING PIC18F2431)
Resource Type
Used
ROM
800 bytes
RAM
65 bytes
MIPS
4.5 MIPS
CONCLUSION
Sensorless control of BLDC motors has several advantages, such as reduction of total system cost and
increased reliability. However, it requires extra
resources on the control circuit side. The specialized
peripherals
on
PIC18FXX31
microcontrollers
(PCPWM, Motion Feedback Module and the
High-Speed A/D converter) can simplify the sensorless
control up to a great extent. This application note demonstrates the implementation of sensorless control of a
BLDC motor using the 28-pin version of the
PIC18FXX31 microcontroller family, the PIC18F2431.
© 2005 Microchip Technology Inc.
DS00970A-page 11
AN970
NOTES:
DS00970A-page 12
© 2005 Microchip Technology Inc.
© 2005 Microchip Technology Inc.
3
4
3
4
S3
S2
100
2
1
2
1
C5
2
1
R19
4K7
R17
+5V
R18
4K7
R16
+5V
33 pF
C9
3
VREF
POT
0.1 uF
S1
+5V
R15
R14
2K
3
4
1
C10
4K7
4K7
RC0
RC5
33 pF
5 MHz
J15
2
VBUS
2K
OSC2
OSC1
HALLC
HALLB
HALLA
IMOTOR
MCLR
R12
+5V
MCLR
VDD
RA3
RA4
PIC18F2431
RC7
8
AVSS
19
VSS
RC5
RC4
RC3
RC6
OSC1
RC2
RC1
RC0
RB7
RB6
RB5
RB4
RB3
RB2
RB1
RB0
21
28
27
26
25
24
23
22
18
17
16
15
14
13
12
11
0.1 uF
OSC2
10
9
7 AVDD
6
5
2 RA0
3
RA1
4 RA2
1
20
U1
RX
TX
RC5
RC4
RC3
RC2
FAULTA
RC0
RB7
RB6
PWM4
PWM5
PWM3
1 uF
C6
RX
TX
6
RB5
T2IN
T1IN
C1+
V-
C2-
C2+
R2IN
GND
15
R2OUT
R1IN
5
4
8
13
T1OUT 14
7
T2OUT
VCC
16
MAX232
U2
+5V
C1
2
J16
1 uF
C7
1
J17
1
R66
10
R13
5
2
J1
8
9
7
6
RB6
FAULTA
R65
PIN1
PIN6
PIN2
PIN7
PIN3
3
PIN8
PIN4
4
PIN9
PIN5
1
2
+5V
PWM5
PWM4
PWM3
PWM2
PWM1
PWM0
+5V
1 uF
RD0 15
VDD 20
VSS 19
18
RF2
17
RF3
RE8 16
AVDD 28
27
AVSS
26
RE0
25
RE1
24
RE2
23
RE3
22
RE4
RE5 21
dsPIC30F2010
R1OUT
1 uF
C8
RB2
8
AVSS
9
OSC1
10
OSC2
11
RC13
12
RC14
13
VDD
14 RD1
3 C1-
1
9
12
10
11
RB0
5 RB3
6 RB4
7
4
U3
MCLR
3 RB1
2
1
1 uF
2 V+
C4
+5V
+5V
RB7
RC5
RC0
OSC2
OSC1
PWM1
PWM2
HALLB
HALLC
PWM0
HALLA
POT
IMOTOR
VBUS
MCLR
2K
2K
RX
TX
FIGURE A-1:
0.1 uF
C3
+5V
APPENDIX A:
10K
R11
+5V
C2
470
R10
AN970
MOTOR CONTROL CIRCUIT SCHEMATICS
PART 1 (PIC18F MICROCONTROLLER, dsPIC30 DSP, USART AND ASSOCIATED
PARTS)
DS00970A-page 13
DS00970A-page 14
11
10
9
8
7
6
5
4
3
2
1
2
1
1
0.1R
605HR100
R26
2
J10
J9_11
J9_10
J9_9
+5V
M1
M2
M3
DC+
V_IN
R36
47 nF
1K
R61
1K
R59
47 nF
2
47 nF
C23
+
–
10K
R56
MCP6002
3
2K2
300
R52
27K
C21
R50
R49
2K2
300
27K
C19
47 nF
R44
2K2
R42
DC-
C22
C17
47 nF
300
R35
R41
27K
R34
4
8
+5V
1
+5V
C25
R74
0.1 uF
J13
J11
J7
U10:A
3
2
1
3
2
1
3
2
1
33 pF
C14
1K
R58
R31
10K
R51
10K
R43
10K
33 pF
C24
300 IMOTOR
100K
R40
100K
R30
100K
R27
100K
R28
2K4
+5V
R55
9
13
R60
5K
12
MCP6544
1M
R53
10
MCP6544
R46
6
5
MCP6544
R37
3
MCP6544
2
+
–
+
–
1M
+
–
1M
+
–
C15
1M
U7:D
14
8
U7:C
7
U7:B
U7:A
1
0.1 uF
R57
11
4
+5V
R73
300
R48
300
R39
300
R32
2
2
2
300 FAULTA
HALLC
1
J14
HALLB
1
J12
HALLA
1
J8
5
6
+
7
U10:B
MCP6002
–
FIGURE A-2:
ED2324
J9
J3
AN970
BOARD SCHEMATIC, PART 2 (BACK EMF SIGNAL CONDITIONING AND
CURRENT FAULT DETECTION)
© 2005 Microchip Technology Inc.
© 2005 Microchip Technology Inc.
6 7 8
J4
2
3
5
4
1
2
V_IN
300
R72
J5
300
R71
+15V
300
R70
1
PWM4
PWM5
PWM2
300
R69
+15V
300
R68
1
U9
2
+15V
+
C20
3.3 uF
+15V
+
C18
3.3 uF
+15V
+
C16
3.3 uF
MC7815CD2T/R4
3
VOUT
VIN
+
GND
C13
2
47 uF
VR2
1
J18
8
7
6
1
5
4
8
7
6
1
5
4
8
7
6
1
5
4
VB
HO
VS
VCC
LO
COM
IR2101S
2 HIN
3
LIN
US1K
D6
VB
HO
VS
VCC
LO
COM
IR2101S
2 HIN
3
LIN
U8
US1K
D5
VB
HO
VS
VCC
LO
COM
IR2101S
2 HIN
3
LIN
U6
US1K
D4
33R
R54
33R
R47
33R
R45
33R
R38
33R
R33
33R
R29
3
C28
0.1 uF
3
M3
3
C11
47 uF
+15V
Q6
IRFR2407
3
Q5
IRFR2407
DC-
2
2
M2
Q4
IRFR2407
DCDC+
2
3
Q3
IRFR2407
DC+
2
M1
Q2
IRFR2407
DC-
2
Q1
IRFR2407
3
+15V
1
1
1
1
1
1
2
DC+
+
R20
10K
1
2
1
J9_11
J9_10
J9_9
J19
1
2
VR1
+5V
PWM1
1K
R2
1K
R3
10K
R24
1K
R4
R25
R22
R21
10K
R23
1K
R5
1K
R6
PWM5
C27
0.1 uF
+5V
1K
1K
1K
1K
R62
HALLC
HALLB
HALLA
PWM5
PWM4
PWM4
PWM3
PWM3
PWM2
PWM2
PWM1
MC7805CD2T/R4
3
VOUT
VIN
+
GND
C26
C12
2
47 uF
0.1 uF
J2
PWM0
1K
R1
PWM0
D1
1K
R7
RC4
D7
D2
1K
R8
D3
1K
R9
DC+
2K4
R64
12K
R63
RB6
RB7
6
5
4
3
2
ICD 1
+5V
RC3
MCLR
RC2
0.1 uF
C29
VBUS
J6
FIGURE A-3:
PWM3
PWM0
PWM1
300
R67
+15V
AN970
BOARD SCHEMATIC, PART 3 (MOTOR DRIVER BRIDGE, POWER SUPPLY AND
REGULATORS, LEDS AND OTHER CONNECTORS)
DS00970A-page 15
AN970
NOTES:
DS00970A-page 16
© 2005 Microchip Technology Inc.
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•
Microchip is willing to work with the customer who is concerned about the integrity of their code.
•
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED,
WRITTEN OR ORAL, STATUTORY OR OTHERWISE,
RELATED TO THE INFORMATION, INCLUDING BUT NOT
LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE,
MERCHANTABILITY OR FITNESS FOR PURPOSE.
Microchip disclaims all liability arising from this information and
its use. Use of Microchip’s products as critical components in
life support systems is not authorized except with express
written approval by Microchip. No licenses are conveyed,
implicitly or otherwise, under any Microchip intellectual property
rights.
Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, microID, MPLAB, PIC, PICmicro, PICSTART,
PRO MATE, PowerSmart, rfPIC, and SmartShunt are
registered trademarks of Microchip Technology Incorporated
in the U.S.A. and other countries.
AmpLab, FilterLab, Migratable Memory, MXDEV, MXLAB,
PICMASTER, SEEVAL, SmartSensor and The Embedded
Control Solutions Company are registered trademarks of
Microchip Technology Incorporated in the U.S.A.
Analog-for-the-Digital Age, Application Maestro, dsPICDEM,
dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR,
FanSense, FlexROM, fuzzyLAB, In-Circuit Serial
Programming, ICSP, ICEPIC, MPASM, MPLIB, MPLINK,
MPSIM, PICkit, PICDEM, PICDEM.net, PICLAB, PICtail,
PowerCal, PowerInfo, PowerMate, PowerTool, rfLAB,
rfPICDEM, Select Mode, Smart Serial, SmartTel and Total
Endurance are trademarks of Microchip Technology
Incorporated in the U.S.A. and other countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2005, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received ISO/TS-16949:2002 quality system certification for
its worldwide headquarters, design and wafer fabrication facilities in
Chandler and Tempe, Arizona and Mountain View, California in
October 2003. The Company’s quality system processes and
procedures are for its PICmicro® 8-bit MCUs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.
© 2005 Microchip Technology Inc.
DS00970A-page 17
WORLDWIDE SALES AND SERVICE
AMERICAS
ASIA/PACIFIC
ASIA/PACIFIC
EUROPE
Corporate Office
2355 West Chandler Blvd.
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Tel: 480-792-7200
Fax: 480-792-7277
Technical Support:
http://support.microchip.com
Web Address:
www.microchip.com
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Tel: 61-2-9868-6733
Fax: 61-2-9868-6755
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10/20/04
DS00970A-page 18
© 2005 Microchip Technology Inc.
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