AN392

Universal motor drive

Doc ID 1863 Rev 2

3/11

Figure 2.

Motor drive circuit diagram

1.3

Circuit components

The MCU chosen (ST6210) includes an 8 bit accumulator, 2 k ROM, 64 bytes RAM, an 8 bit

A/D converter that can be connected to 8 different inputs, 4 I/O lines with 40 mA sink current

capability and a timer. Hysteresis protection is included in series with each I/O pin. The

ST6210 is packaged in DIL or SMD packages. The ports, the timer and interrupt

configurations can be chosen by software, providing high flexibility. The ST6210 has been

designed to operate in very disturbed environments. Each I/O line contains internal diodes

continuous current of 1 mA (typ.).

The snubberless TRIAC (BTA 16-600CW) has been specially designed to drive loads which

generate very strong dynamic constraints such as a vacuum cleaner motor. This TRIAC can

be triggered in quadrants QI, QII or QIII with gate and latching current of 35 mA and 80 mA

respectively. In this application it is driven by three I/O lines of the ST6210 in parallel. This

TRIAC has high current switching capability ((dI/dt)c > 8.5 A/ ms and 5.5 A/ms for

BTA10600CW), and high static dv/dt ((dV/dt) > 500 V/ms). So, in this circuit, it can operate

without any snubber.

Total consumption of the board is 3 mA with an 8 MHz oscillator. The board supply comes

from the mains through a simple RCD circuit. The +5 V is referred to anode 1 of the TRIAC

in order to provide the negative gate current necessary to drive the TRIAC in quadrants QII

and QIII. The 5 V supply capacitance is connected as near as possible to the MCU with very

short interconnecting traces to maximize RFI immunity.

The touch sensor is a voltage divider between line and neutral. It works only if the +5 V

supply input of the circuit is connected to the line. This connection to the mains must be

ensured according to local electrical safety rules.

5.6 V

1N4148

100 uF/10 V

22 pF

22 pF

BTA16-600CW

1M

820-1/2W

4.7 M

4.7 M

4.7 M

47

220 nF/400 V

Fuse

Potentiometer

Version

Push button

1

2

8 MHz

VPP

6

PB1

14

PB0

15

VSS

20

NMI

5

PA1

18

PA2

17

PA3

16

PB3

12

RESET

7

PB4

11

PB2

13

PA0

19

ST6210

5.6 V

1N4148

-

1M

820-1/2W

47

Fuse

1

2

8 MHz

VPP

6

PB1

14

PB0

15

VSS

20

NMI

5

PA1

18

PA2

17

PA3

16

PB3

12

RESET

7

PB4

11

PB2

13

PA0

19

ST6210

GND

GND

GND

GND

GND

GND

GND

Optional

user interface

Neutral

Load

Line

+5 V

+5 V

+5 V

Touch sensor

10 nF

GND