Resistor values for the opto supply, Sing more than, 5vdc – RMS Technologies IMD 34 W/ POLE DAMPING TECHNOLOGY*NEW* User Manual

Page 22: For external supply for the optos, Esistor, Alues for the, Upply

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RMS Technologies

Page 22

Version 1.00

IMD34 / IMDE34 User Manual

4/28/2009


Using more than 5VDC for external supply for the optos

If using more than 5VDC, connect
resistors in series with the opto
supply input, PIN 2. Use the table
below to determine what resistor
to use.

Connect the 5VDC supply ground
terminal to the IMD’s Ground, PIN
9.

Figure 22: Schematic for more than 5VDC






Resistor Values for the Opto Supply

The optocouplers must be powered by an external power supply to maintain isolation. The
Opto Supply for the optocouplers can be between +5 to 24 VDC with respect to the signal
input. It is recommended to use a +5 VDC Opto Supply in order to limit the current going
into the optocouplers to 10 mA. However, if the supply is greater than +5 VDC then a
resistor must be connected in series with each signal line to maintain 10 mA of current
running through the optocouplers (step, direction, and disable lines). Do NOT provide
more than 10 mA or damage may occur to the driver.


Step, Direction, and Disable lines have a 475 ohm internal resistor

Voltage:

5V

10V

12V

15V

24V

Ohms needed:

0

500

668

1000

2000

Wattage rating:

0

¼ watt

¼ watt

¼ watt

½ watt

Table 6: Required resistance for more than 5VDC on opto supply input

If the desired voltage level is not listed above, below is how to calculate the resistor and
wattage:

Amps

R

Voltage

010

.

0

475

=

+

or





=

475

010

.

0

Amps

Voltage

R

Amps

Voltage

Power

×

=

or

Amps

Voltage

Wattage

010

.0

Ч

=

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