Atmel AVR430-MC300 User Manual

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, Im

• 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.

max

=6A

8-bit
Microcontrollers

Application Note

Rev. 8124C-AVR-10/08

2 Hardware overview

2.1 Specifications

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.

MC300 maximum ratings with components as delivered:
Input:

• Vin: 10 – 20VDC

• Vm: 0 – 40VDC, Im

Output ratings:

• Vcc = 3.3/5V, I

• Vha = 5V, I

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).

max

= 0.1A

max

= 6A

max

= 0.5A

2.1.1 Necessary precautions

2

AVR430

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.

8124C-AVR-10/08

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.

AVR430

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.

8124C-AVR-10/08

3

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)

J2 (VCC)

J1 pin 1 & 2 connected – VHa = 5V (from separate regulator)

Selects voltage from onboard regulated supply (Vcc).
J2 connected – Vcc = 3.3V
J2 open – Vcc = 5V

4

AVR430

8124C-AVR-10/08