WYFFOS - SMD4 THREE AXIS 4 PHASE STEPPER MOTOR DRIVE CARD

WYFFOS - SMD4 THREE AXIS 4 PHASE STEPPER MOTOR DRIVE CARD DRIVER

Contents:

1. Introduction

The SMD4 three axis 4 phase stepper motor drive card has been designed to provide three independent drive circuits to control four phase stepper motors with a phase current of less than 1.25amps. In the WYFFOS instrument it is used to control the two filter slides and the slit focus which are all moved by 4 phase linear actuators.

1.1 Document History

1.2 Version notes

1.3 Mnemonics used throughout the text

2. Circuit Description

2.1 Physical

The circuit card is a 3U x 160mm eurocard with a DIN 41612 edge connector and is mounted vertically in the WYFFOS LIMPIT sub-rack. A free flow of air around the card is required, forced cooling is unnecessary

2.2 Electrical

The circuit consists of three identical drives therefor only one drive shall be explained. The drive has four inputs : Enable, Direction, Step and Half/Full. Each input is via an opto-coupler with a series resistor so that they can be driven from any 5V signal which does not need to be referenced to the same supply that provides the power to the card and the motors. Each output from the opto-couplers is pulled-up and input to and exclusive-OR gate. The other input to the exclusive-OR gate can be selected to be a logic 1 or logic 0 by either fitting or removing a jumper link. This has the effect of either inverting or not inverting the sense of the input signal. This enables the card to be used with different controllers that may have different sense outputs. The outputs of the logic gates are then feed into the 4 phase drive chip (UCN5804B) with the inclusion of pull-up resistors as the UCN5804B inputs are CMOS level and are being driven by LS gates.

The UCN5804B has six output connections, one for each of the phases (OpA, OpB, OpC and OpD) and two commons (Kac, Kbd). When the enable is set and a clock is applied to the step input then the four outputs are grounded in sequence energizing the coils of the motor causing it to rotate. A copy of the manufactures data sheet is included in Appendix A for further details.

In the WYFFOS application the motors used have 12V coils and do not require a series resistor. From previous experience it has been found that the drive chips can be damaged when they are enabled with a voltage applied to the Kac and Kbd pins and no connection to the outputs. To avoid this the 12V supply is connected to the drive chip via all the connectors that connect the motor to the drive chip therefor if the motor is disconnected then the 12V is also removed from the drive chip. An example of the connections are shown below.

3. Circuit diagrams

3.1 Drive 1

3.2 Drive 2

3.3 Drive 3

3.4 Interface and Power Supplies

4. Parts list

Circuit Component        Manufacturer & Supplier   No.   Cost
Ref.                     part           & order    off    per
                         number         code             item
        100 x 160        Bicc Vero      Electrosp   1    £8.49
        circuit board    03-0026J       eed
                                        03-0026J
        Card Ejectors    Bicc Vero      Electrosp   1    £1.29
                         173-26513C     eed
                                        173-
                                        26513C
J1      Connector        Harting        Electrosp   1    £4.28
        class 2          0903.164.6928  eed
        W/wrap 64/96                    17-1222E
U1,U3,U Translator/Dri   Allegro        RS          3    £4.39
5       ver              Microsystems   653-531
U2,U4,U 2 input XOR      Motorola       RS          3    £1.66
6       gate IC.         SN74LS86N      644-234
RP2,RP4 4 Individual     Beckman        RS          3    £0.18
,       470R SIL         Industrial     168-601
RP7     package          L83S471
RP3,RP5 8 Common         Beckman        RS          3    £0.21
,       4K7 SIL          Industrial     140-962
RP8     package          L91S472
RP1,RP6 8 Common         Beckman        RS          2    £0.21
        10K SIL          Industrial     140-978
        package          L91S109
ISO1,IS Opto-Isolator    Sharp          RS          3    £1.59
O2,                      PC847          175-132
ISO3
JP1 -   PCB Jumper                      RS          1    £3.71
JP12    Header                          334-549
        Jumper Links                    RS          12   £0.38
                                        334-561
C1,C3,C 0.1µF            AVX Kyocera    RS          6    £0.602
5,      decoupling                      125-806
C8,C9,C capacitor
10      ceramic
C2,C4,C 200µF 25V        Panasonic      RS          3    £0.286
6       Electrolytic                    107-038
C7      470µF 25V        Panasonic      RS          1    £0.382
        Electrolytic                    107-044
Original Document smd4.doc by M. A. Parr RGO Cambridge

Converted to HTML by M. A. Parr map@mail.ast.cam.ac.uk