AVR430: MC300 Hardware User Guide Features 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 Electric specifications: - Driver circuit: Vin 10-20V - Motor: Vm 0-40V, Immax=6A • Dimension: 100x100mm • • • • • • • 8-bit Microcontrollers Application Note 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. Rev. 8124C-AVR-10/08 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 windings). Four 8-pin 2,54mm (100mil) horizontal female pin headers on the left side of the board form a system connector for device boards. The board has an adjustable voltage regulator for Vcc, 3.3V or 5V, and this voltage is available on the system connector. A 5V regulator powers the Hall sensors. Vm, Vin and Vcc each have their own LED to indicate power. 2.1 Specifications MC300 maximum ratings with components as delivered: Input: • Vin: 10 – 20VDC • Vm: 0 – 40VDC, Immax = 6A Output ratings: • Vcc = 3.3/5V, Imax = 0.5A • Vha = 5V, Imax = 0.1A The driver stage consists of four half-bridges capable of 40V / 30A (Warning! Other components such as shunt resistors limit the maximum current to 6A). 2.1.1 Necessary precautions The gate voltage to the high side MOS is powered by a bootstrap capacitor. To sustain the voltage over this capacitor the high side must be turned off for a short time on a regular basis, allowing the capacitor to be recharged via a diode. Failing to do so, for example. by keeping the high side permanently on, will cause the gate voltage on the high side MOS to drop and the internal resistance to increase. If a high current is going thru the high side MOS at this point the transistor will overheat and be destroyed. The fuse will not prevent this from happening. 2 AVR430 8124C-AVR-10/08 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 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. 3 8124C-AVR-10/08 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. 4 Designator Use and settings J1 (VHa) Selects voltage source to Hall sensors (VHa) J1 open – VHa not connected J1 pin 2 & 3 connected – VHa = Vcc J1 pin 1 & 2 connected – VHa = 5V (from separate regulator) J2 (VCC) Selects voltage from onboard regulated supply (Vcc). J2 connected – Vcc = 3.3V J2 open – Vcc = 5V AVR430 8124C-AVR-10/08 AVR430 Table 2-2. MC300 device board connector signal description. Pin Located Name Direction Description 1 J9p1 GND - 2 J9p2 GND - 3 J9p3 GND - 4 J9p4 Vin Output 5 J9p5 VCC Output 6 J9p6 VCC Output 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 input 12 J11p4 VL Input Phase V Lowside control input 13 J11p5 WH Input Phase W Highside control input 14 J11p6 WL Input Phase W Lowside control input 15 J11p7 XH Input Phase X Highside control input 16 J11p8 XL Input Phase X Lowside control input 17 J13p1 GNDm - Motor ground (Vmotor) 18 J13p2 Vmotor’ Output Vmotor filtered/divided 19 J13p3 ShCom’ Output Voltage over ShCom filtered/divided 20 J13p4 ShU’ Output Voltage over ShU filtered/divided 21 J13p5 U’ Output BackEMF phase U filtered/divided 22 J13p6 ShV’ Output Voltage over ShV filtered/divided 23 J13p7 V’ Output BackEMF phase V filtered/divided 24 J13p8 ShW’ Output Voltage over ShW filtered/divided 25 J15p1 W’ Output BackEMF phase W filtered/divided 26 J15p2 ShX’ Output Voltage over ShX filtered/divided 27 J15p3 X’ Output BackEMF phase X filtered/divided 28 J15p4 GND - System ground (Vin/VCC) 29 J15p5 H1 Output Hall sensor 1 signal 30 J15p6 H2 Output Hall sensor 2 signal 31 J15p7 H3 Output Hall sensor 3 signal 32 J15p8 Vn’ Output Vn (neutral point) filtered/divided System ground (Vin/VCC) Input power Vin (10-20V) Regulated power Vcc (3.3V/5V) 5 8124C-AVR-10/08 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 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 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 downloaded from http://www.atmel.com. 7 8124C-AVR-10/08 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. 8 AVR430 8124C-AVR-10/08 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 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. 9 8124C-AVR-10/08 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. 10 AVR430 8124C-AVR-10/08 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 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. 11 8124C-AVR-10/08 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 Limiting parameter Q3, Q4, Q5, Q6, Q7, Q8, Q9 & Q10 IRFR3504 VDSS = 40V C10, C19, C26 & C33 100nF Vmax = 50V Q2 2N7002 VDSmax = 60V C14 47uF/63V Vmax = 63V D8, D12, D13 & D14 BAS16 VRRM = 85V D9 10MQ100N VRRM = 100V D11 12CWQ10FN VRRM = 100V C7 10nF Vmax = 100V [2] R7 100kOhm Pmax = 0.1W -> Vm = 108V 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 Limiting parameter R62 50mOhm 2W Imax = sqrt(P/R) = 6,0A J3 & J7 MC1,5/x-G-3,81 Imax = 8A Q3, Q4, Q5, Q6, Q7, Q8, Q9 & Q10 IRFR3504 ID = 30A Notes: (1) 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). 12 AVR430 8124C-AVR-10/08 D Headquarters International Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131 USA Tel: 1(408) 441-0311 Fax: 1(408) 487-2600 Atmel Asia Room 1219 Chinachem Golden Plaza 77 Mody Road Tsimshatsui East Kowloon Hong Kong Tel: (852) 2721-9778 Fax: (852) 2722-1369 Atmel Europe Le Krebs 8, Rue Jean-Pierre Timbaud BP 309 78054 Saint-Quentin-enYvelines Cedex France Tel: (33) 1-30-60-70-00 Fax: (33) 1-30-60-71-11 Atmel Japan 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chuo-ku, Tokyo 104-0033 Japan Tel: (81) 3-3523-3551 Fax: (81) 3-3523-7581 Technical Support [email protected] Sales Contact www.atmel.com/contacts Product Contact Web Site www.atmel.com Literature Request www.atmel.com/literature Disclaimer: The information in this document is provided in connection with Atmel products. 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