AVR430: MC300 Hardware User Guide
Features
8-bit
Microcontrollers
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General-purpose power stage for DC and stepper motors
Modular system with 2,54mm pin header connector for device boards
Four half-bridges with independent control of high and low side
Onboard voltage regulators for device board (5/3,3V) and Hall sensors (5V)
Hall sensor, back-EMF and center voltage feedback to device board
Shunt resistor feedback to device board
Application Note
Electric specifications:
-
-
Driver circuit: Vin 10-20V
Motor: Vm 0-40V, Immax=6A
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Dimension: 100x100mm
1 Introduction
The MC300 is a general-purpose power stage board able to drive brushless DC,
brushed DC and stepper motors. The board is designed to be a flexible platform for
developing motor control applications. Power and all signals needed for a controller
(AVR® CPU) are available on the left side of the board, giving a modular system
where boards with different microcontrollers can easily be connected.
Figure 1-1. MC300 Motor control driver board.
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2.2 Connections
Figure 2-1. MC300 with device board, connector details and prototype board fitted.
2.2.1 Device board connector
The MC300 driver board can directly connect to an AVR device board. This is
accomplished by a horizontal female 0.1” pin header connector located on the left
side of the board, shown in Figure 2-1.
The device board interface on MC300 connector is split into four eight-pin connectors.
Electric schematics and mechanical specifications are shown in Figure 2-2 and
signal description in Table 2-2.
The connectors are mounted on the same 0.1” grid. The grid is positioned so the
connectors will fit an angled pin header on a prototype Vero-board, shown in Figure
2-1.
2.2.2 Power and motor connectors
The board has two power connectors located on the top, one 4 pin 3.81mm connector
(J3) and one DC-jack (J5) with 2.0mm center tap. J3 allows for separate power inputs
to Vin and Vm, while J5 powers both Vin and Vm via diodes. Refer to chapter 4.1 for
more details.
The motor connector (J7), a 10 pin 3.81mm connector, is found on the lower right
side of the board. Signals and voltages associated with the motor are easy accessible
on the pin row (J6) above the motor connector. Refer to the schematics for signals
and pinout on J6 and J7.
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Figure 2-2. Device board connector mechanical specification and schematics.
2.3 Jumpers
Refer to component floorplan for location of jumpers.
Table 2-1. Jumpers and their functions.
Designator
Use and settings
Selects voltage source to Hall sensors (VHa)
J1 open
– VHa not connected
J1 pin 2 & 3 connected
J1 pin 1 & 2 connected
– VHa = Vcc
J1 (VHa)
J2 (VCC)
– VHa = 5V (from separate regulator)
Selects voltage from onboard regulated supply (Vcc).
J2 connected
J2 open
– Vcc = 3.3V
– Vcc = 5V
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Table 2-2. MC300 device board connector signal description.
Pin
Located
J9p1
J9p2
J9p3
J9p4
J9p5
J9p6
J9p7
J9p8
Name
GND
GND
GND
Vin
Direction
Description
1
-
2
3
4
5
6
7
8
-
System ground (Vin/VCC)
Input power Vin (10-20V)
Regulated power Vcc (3.3V/5V)
System ground (Vin/VCC)
-
Output
Output
Output
Output
-
VCC
VCC
VCC
GND
9
J11p1
UH
UL
VH
VL
Input
Input
Input
Input
Input
Input
Input
Input
Phase U Highside control input
Phase U Lowside control input
Phase V Highside control input
Phase V Lowside control input
Phase W Highside control input
Phase W Lowside control input
Phase X Highside control input
Phase X Lowside control input
10 J11p2
11 J11p3
12 J11p4
13 J11p5
14 J11p6
15 J11p7
16 J11p8
WH
WL
XH
XL
17 J13p1
18 J13p2
19 J13p3
20 J13p4
21 J13p5
22 J13p6
23 J13p7
24 J13p8
GNDm
-
Motor ground (Vmotor)
Vmotor filtered/divided
Vmotor’ Output
ShCom’ Output
Voltage over ShCom filtered/divided
Voltage over ShU filtered/divided
BackEMF phase U filtered/divided
Voltage over ShV filtered/divided
BackEMF phase V filtered/divided
Voltage over ShW filtered/divided
ShU’
U’
Output
Output
Output
Output
Output
ShV’
V’
ShW’
25 J15p1
26 J15p2
27 J15p3
28 J15p4
29 J15p5
30 J15p6
31 J15p7
32 J15p8
W’
Output
Output
Output
-
BackEMF phase W filtered/divided
Voltage over ShX filtered/divided
BackEMF phase X filtered/divided
System ground (Vin/VCC)
Hall sensor 1 signal
ShX’
X’
GND
H1
Output
Output
Output
Output
H2
Hall sensor 2 signal
H3
Hall sensor 3 signal
Vn’
Vn (neutral point) filtered/divided
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3 PCB
3.1 PCB Layout
The MC300 is organized as shown in Figure 3-1. Most signals, important components
and jumper information are written on the silk screen. For individual component
placement refer to the component floorplan.
Figure 3-1. MC300 PCB layout.
In Figure 3-1 the following areas are marked:
1. Device board connector.
2. Power connectors
3. Motor connector
4. Phase area
5. Indicator LEDs for power
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3.1.1 Phase area
Each phase has its own area with a frame drawn on silkscreen. In Figure 3-2 the area
for phase ‘V’ is shown, and everything inside this frame regards this phase only.
Figure 3-2. Phase ‘V’ area on MC300 PCB.
From the left we see:
1. Shunt filter/damping block – denoted ‘Sh’
2. Back EMF filter/damping block – denoted ‘EMF’
3. Shunt resistor testpoints – denoted ‘-‘ and ‘+’ (above shunt resistor)
4. Bootstrap voltage testpoint – denoted ‘Vboot’
5. MOS Gate voltage testpoints – denoted ‘VGl’ (low side) and ‘VGh’ (high side)
3.1.2 Common shunt and filters/dividers
The common shunt (R62) with testpoints is found above phase ‘U’ and denoted
‘ShCom’. Filters/dividers for Vm, ShCom and Vn are found on the left of the phase
areas.
3.2 Schematics, component floorplan and bill of materials
The schematics, component floorplan and bill of materials (BOM) for MC300 are
found as separate PDF files distributed with this application note, they can be
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4 Detailed description
4.1 Power
The MC300 has two power circuits. Vin for powering driver ICs and voltage
regulators, and Vmotor (Vm) for powering the output stage (MOSFETs). The separate
power supply for the motor, Vm, allows the use of motor voltages outside the voltage
range of the driver ICs. This also isolates noise generated by the output stage/motor.
There is a separate ground plane for each power circuit, GND for Vin and GNDmotor
(GNDm) for Vm. This is done to separate the high currents to the motor from the rest.
The ground planes are connected together at one single point, under the J3
connector (shown in Figure 4-1).
A regulated power supply for Vcc is included on the board. The voltage for Vcc is
selectable by J2, if open Vcc = 5V and if set Vcc = 3.3V.
4.1.1 Input
The MC300 can be powered in two ways. With J3, a four pin 3,81mm pitch connector,
separate power supplies can be connected to Vin and Vm. But it is also possible to
power the MC300 from a single DC-Jack connector, J5. J5 is connected to Vin and
Vm via diodes as shown in Figure 4-1. When J5 is used as power input, the supply
voltage must not exceed 20V and maximum current is 5A.
Figure 4-1. MC300 Power input.
4.1.2 Fuses
Vin is protected by a resettable 0,75A polyfuse (F1). If the current through it exceeds
0,75A, the fuse will heat up and go into a high resistance mode for as long as the load
is retained, and will reset when allowed to cool down.
A socket mounted 6,3A 5x20 mm fuse protects Vm (F2). Using a socket mounted
fuse allows the user to replace and change it easily. When developing software it is
also practical to not power the output stages until correct operation of the software is
ensured, and this can be done by simply removing the fuse.
4.1.3 LEDs
Vcc, Vin and Vm each have their own green LED to indicate if voltage is present. The
Vcc LED (D3) is connected to Vcc by a resistor and hence it will emit less light when
Vcc is 3,3V. Vin and Vm LEDs (D1 and D2) have a constant current sources, so they
have a constant intensity even if Vin or Vm changes.
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4.1.4 Hall sensors
VHall (VHa) is available on J7 as power source for Hall sensors, typically found on
BLDC motors. With J1 VHa can be connected to Vcc or to a 5V regulator (U2). A
separate 5V regulator for the Hall sensors is included so Vcc can be 3,3V while using
Hall sensors, since most Hall sensors will not work on 3,3V.
4.2 Half bridges
The half bridge consists of two n-channel power MOSFETs, driven by an integrated
high and low side driver IC (IR2101S). The integrated driver IC is powered from Vin
and provides gate voltages to the high and low side power MOSFETs. Schematics for
the half bridge for phase U is shown in Figure 4-2
Figure 4-2. Phase U half bridge.
4.2.1 High side driving considerations
The high side of the half-bridge uses a bootstrap circuit. This means the duty cycle
and the on-time are limited by the requirement to refresh the charge in the bootstrap
capacitor. If the driving logic fails to do this, the gate voltage to the high side MOS will
decrease and the RDS will increase. This may result in high power dissipation in the
high side MOS, and consequently destroy it.
Refer with IR2101S datasheets for detailed information about the bootstrap circuit.
4.2.2 Test points
Each half bridge has several testpoints to allow for measurements. MOS gate
voltages for high (VGh) and low-side (VGl) and bootstrap voltage (Vboot) are
available. Both sides of the shunt resistors (- and +) can also be measured.
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4.3 Shunts
The board is shipped with a common shunt resistor (ShCom - R62) of 0,050 ohm and
the four phase shunt resistors are zero ohm resistors, shown in Figure 4-3. This
allows for measurement of the total current going to ground via all half bridges.
Figure 4-3. Shunt resistor network.
If current measurements of separate phases are required, the common shunt should
be changed to a zero ohm resistor and the zero ohm resistors on each phase (ShU -
R27, ShV - R38, ShW - R49 and ShX - R64) should be replaced with appropriate
shunt resistors.
4.3.1 Shunt feedback filters
The voltages over the shunt resistors (ShCom/ShU/V/W/X) are fed to a filter/damping
block, ShU as shown in Figure 4-4. The board is shipped with a filter that consists of a
10k ohm resistor in series with a 10nF capacitor, resulting in a low pass filter with a
1,6kHz cutoff frequency. The signal from the filters (ShCom’/ShU’/V’/W’/X’) are
available on the device board interface.
Figure 4-4. Filter/damping block for shunt feedback.
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4.4 Back-EMF
For sensorless applications, the driving logic uses back EMF from the motor’s phases
to keep track of the motor position. To observe the back EMF from a phase, the
phase is left floating, i.e. with the high or low side MOS not powered, and the voltage
on the phase is read. For motors with center tap, Vn (V neutral) provides feedback to
device board.
4.4.1 Back-EMF feedback filters
Each phase (U/V/W/X) and the center tap (Vn) are fed via a filter/damping block to
the device board interface. The block for phase U is shown in Figure 4-5. The board
is shipped with a zero ohm resistor, so it has no damping/filter function. The signals
are named U’, V’, W’, X’ and Vn’ after going through the filter blocks.
Vmotor (Vm) is also fed thru a filter/damping block, and is available on the device
board interface as Vm’.
Figure 4-5. Filter/damping block for back-EMF feedback.
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4.5 Upgrading the MC300
As the board is shipped, its limitations are Vmmax=40V and Immax=6A. These limits can
be increased by replacing the relevant components (not included).
4.5.1 Voltage limitations
If a Vmmax higher than 40V is required, then some components must be changed on
the board. Components limiting Vm, listed with lowest voltage ratings first, are shown
in Table 4-1.
Table 4-1. Components influenced by Vm.
Component designator(s)
Component name
IRFR3504
100nF
Limiting parameter
VDSS = 40V
Q3, Q4, Q5, Q6, Q7, Q8, Q9 & Q10
C10, C19, C26 & C33
Vmax = 50V
Q2
2N7002
VDSmax = 60V
C14
47uF/63V
BAS16
Vmax = 63V
D8, D12, D13 & D14
VRRM = 85V
D9
10MQ100N
12CWQ10FN
10nF
VRRM = 100V
D11
C7
VRRM = 100V
Vmax = 100V [2]
Pmax = 0.1W -> Vm = 108V
R7
100kOhm
The integrated bridge drivers (IR2101S) can handle up to 600V, but the layout of the
PCB (spacing between tracks) should be considered before operation at high
voltages.
If filters/dividers for Vm, U, V, W, or X have been mounted, verify that they can handle
Vm.
4.5.2 Current limitations
For an Im > 5A, use power connector J3 and not DC-Jack J5. If an Immax larger than
6A is required, components listed in Table 4-2 are affected.
Table 4-2. Components conducting Im.
Component designator(s)
Component name
50mOhm 2W
Limiting parameter
Imax = sqrt(P/R) = 6,0A (1)
Imax = 8A
R62
J3 & J7
MC1,5/x-G-3,81
IRFR3504
Q3, Q4, Q5, Q6, Q7, Q8, Q9 & Q10
ID = 30A
Notes: 1. The pad/track area around R62 is not 300mm2 as required by datasheet for
handling 2W. Reducing P to 1,8W gives Imax = sqrt(P/R) = 6,0A.
4.5.3 Additional decoupling capacitors on Vm
The board has provision for some extra decoupling capacitors on Vm. They are found
close to the MOS bridges (C11, C12, C20, C21, C27, C28, C34 and C35), and one
close to the power input (C13).
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