Example Using 20 M A Servo Valves With 100 M A Output - Delta Computer Systems TMC 188/40 Series Manual

TMC 188/40 Motion Control Module
Example Using 20mA Servo Valves with 25mA Output
C on figure for
25 m A outp ut
V
out = 20 mA x (80 Ohms + 80 Ohms) = 3.2 volts across coils
R = 3.2 volts / 5 mA = 640 Ohms
You can use a this technique to scale the output current (100 mA, 50 mA, or 25 mA) to a lower full
scale current. This lets you use the maximum output resolution of the TMC 188/40 with valves
needing less than one of the full-scale outputs.
To find what wattage of resistor to use, calculate the power dissipation:
2
Power = I x R
so:
2
Power = (5 mA)
A quarter Watt resistor would be a good choice.
Delta Computer Systems, Inc. 360/254-8688
2 5
5 0
x 640 Ohms = 0.016 Watts
TMC 188/40 Wiring Diagrams
5
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