Which is the minimum operating current for a relay?
As the other replies say, the 40mA is your nominal coil operate current, and the 10mA is the minimum ‘wetting’ current that is needed to guarantee the specified closed resistance of the contacts. Different contact materials have different characteristics, generally divided into low voltage and high power.
What’s the minimum switching current for a coil?
The minimum of 10 mA switching current refers to the contact current. This is the minimum load current. The coil specs indicate the requirements for the coil and is indicated in voltage. Ofcourse from there you can calculate the current at the minimum voltage required.
What is the coil resistance for a relay?
The coil resistance is 125 Ω, and when I connect it directly to 5V it works as expected. The current is I = V R = 5 125 = 40 m A. Considering I have a limited power source, and as my understanding the relay only needs 10mA and I’m providing 40mA, I tried to include a 100 Ω in series with the coil.
How does a capacitor close a relay coil?
The trick is to drive the relay coil through a parallel RC combination. The capacitor gets the nominal switching voltage to the relay, for long enough to close it. The resistor is sized to continue to conduct just enough current to hold it closed.
Is there a limit to how fast a relay can be switched?
After operation, the capacitor has to discharge through the resistor, so there is an upper limit to how fast the relay can be switched like this. The relay draws 40 mA at 5V applied directly across it.
How to reduce the current drawn by a relay?
This will reduce the current drawn by the relay too. Let all the available voltage be applied across relay. If you have to reduce the overall current consumption, 3 V relay from the same family is available. For the relay you have, at 5V, 40 mA has to be sacrificed.