SMALL CIRCUITSCOLLECTION

045 Stepper Motor Microstep Driver

5V
5V + < 37V
+
7x 10k
1000µ
100n RESET VCC MO VMA VMB 63V
2 13 11 24 15

M1 ØA BYV27-200
M1 8
DECODER 23
M2 BRIDGE Motor
M2 9 ENABLE
DRIVER Phase A

DECODER
CW/CCW RESET 20
Direction 5
ØA BYV27-200 Table 1. Step settings
CK1
7
TTL-Clock Input Mode
CK2
6 21 M1 M2
Rsense
0Ω8 =
OUTPUT 1A / Phase L L ⁄1 step
1
H-motor off ENABLE
L-motor on 3 CURRENT
CONTROL H L ⁄2 step
1

OSC ØB BYV27-200
L H ⁄4 step
1

4 OSC DECODER
19 H H ⁄8 step
1
ENABLE BRIDGE
3n3 DRIVER Motor
DECODER Phase B
RESET
motor current REF IN 16
H = 100%, L = 65% 10
ØB BYV27-200

MAX OUTPUT
CURRENT CURRENT 18
LIMIT CONTROL Rsense
0Ω8 =
1A / Phase
1 22 17

PG-A PG-A PG-B

(Signal GND) (Power GND A) (Power GND B) 004104 - 11

K. Walraven (text) will run more slowly at the same clock rate.
from a Nanotec application note The motor current is set by the resistor Rsense. The desired cur-
The IMT 901 IC from the German firm Nanotec makes it easy to rent level naturally depends on the motor used. The value of
build a stepper motor controller. You can find a data sheet with R is given by
complete technical specifications at the Nanotec site
(http://nanotec.de). R = 0.8 ÷ (desired current in ampère)
The circuit diagram can be kept very simple. In the applica-
tion shown here, the IC is controlled manually, but it can nat- Use a 5-W resistor. The IC will limit the motor current to this
urally also be controlled by a microcontroller or PC. Signals M1 value using pulse-width modulation. The IC runs from a 5-V
and M2 select the number of current steps for each mechanical supply. The two supply voltages on VMA and VMB must be
step (see Table 1). Bear in mind that the more current steps equal to the specified voltage for the motor used (in practice,
there are, the more clock pulses are needed to move the motor at most 37 V).
by one step. In other words, with more current steps the motor (004104-1)

IMT 901 specifications

INPUT MODE
Supply voltage VCC 5.5 V
CK1 CK2 CW/CCW Enable Reset
Supply voltage VM 40 V H L L H CW
L L L H INHIBIT
Output current Iout 1.5 A (average)
H L L H CCW
2.5 A (peak)
L L L L INHIBIT
Power dissipation Pd 4 W (no heat sink) H H L H CCW
40 W (with heat sink) L H L H INHIBIT
Tc = 85 °C CW
H H L H
Operating temperature –40 to +85 °C L H L H INHIBIT
X X X H H Z
Storage temperature –55 to +150 °C X X X X L Z
004104- 12

12/2000 Elektor Electronics 93