FAQ No. FAQ001906
Question
How do you calculate the control resistance
for A3D/M2D Push Buttons LED lamps?
Answer
Set the control resistance within the range for the LED lamp
characteristics.
(Set the forward current for the LED lamp to 8 mA min.)
Use the following formula to find the external resistance.
Control Resistance (Recommended Values)
|
Voltage |
Red |
Yellow
(White) |
Green |
| 5 VDC |
165 Ω |
140 Ω |
165 Ω |
| 12 VDC |
515 Ω |
490 Ω |
515 Ω |
| 24 VDC |
1,100 Ω |
1,090 Ω |
1,100 Ω |
Calculation Example: A3D
LED lamp color: Red
When E=24V, IF=20mA, and Ta=25°C:
Based on the VF-IF characteristics in the diagram below (red), VF when IF
= 20mA will be 1.7 V.
If this value is entered into the above formula, the result is as follows:
The recommended resistance is 1.1 kΩ 1 W (2 × IF2R). A margin of
approximately two times is appropriate for the resistance capacity.
Applicable models: A3D,
A3A Push Buttons etc.
Other Pushbutton / Indicator Lamp
FAQs
 What is an alternate action?
What can be done if a lighted pushbutton switch does not light when it is pressed?
Does OMRON engrave or print the Legend Plates?
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