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AVR430: MC300 Hardware User Guide
Features
8-bit
• General-purpose power stage for DC and stepper motors
Microcontrollers
• 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
Application Note
• Shunt resistor feedback to device board
• Electric s
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2 Hardware overview Please refer to schematics, layout and BOM available at http://www.atmel.com. The MC300 motor control driver board is a power stage board intended for driving BLDC and stepper motors. It has four half-bridges with independent control of high and low sides. Each bridge has options for filtered/voltage divided feedback from its output (EMF) and shunt resistor. There is also feedback from a common shunt resistor, Vmotor (Vm) and Vneutral (Vn - center tap motor win
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AVR430 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
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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 – VHa = Vcc J1 (VHa) J1 pin 1 & 2 connected – VHa = 5V (from separate regulator) Selects voltage from onboard regulated supply (Vcc). J2 connected – Vcc = 3.3V J2 (VCC)
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AVR430 Table 2-2. MC300 device board connector signal description. Pin Located Name Direction Description 1 J9p1 GND - 2 J9p2 GND - System ground (Vin/VCC) 3 J9p3 GND - 4 J9p4 Vin Output Input power Vin (10-20V) 5 J9p5 VCC Output 6 J9p6 VCC Output Regulated power Vcc (3.3V/5V) 7 J9p7 VCC Output 8 J9p8 GND - System ground (Vin/VCC) 9 J11p1 UH Input Phase U Highside control input 10 J11p2 UL Input Phase U Lowside control input 11 J11p3 VH Input Phase V Highside control i
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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 6 AVR430 8124C-AVR-10/08
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AVR430 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
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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 t
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AVR430 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 integrate
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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 an
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AVR430 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 t
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4.5 Upgrading the MC300 As the board is shipped, its limitations are Vm =40V and Im =6A. These limits can max max be increased by replacing the relevant components (not included). 4.5.1 Voltage limitations If a Vm higher than 40V is required, then some components must be changed on max 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 Limiting param
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