5v Relay voltage ?

[smilem]

Hello, I have a PCB that uses NEC Relays ud2-4.5nu
These are 4.5V relays, but the voltage measured is 4.91V

The datasheet

https://eu.mouser.com/datasheet/2/212/KEM_R7005_UC2_UD2-1104541.pdf

Shows that operating voltage is 3.75V for 5V relay.

How to understand that low 3.75V is specified?

My concern is that life of relay is dramatically reduced if 4.5V are used instead of 5V relays and to make it even worse they work at 3.75V?

 

[Pommie]

The datasheet is for a range of different voltage relays. Yours is the 4.5V one. If you're worried about it the either use the 5V version or stick a resistot or diode in series with it.

Mike.

 

[smilem]

The datasheet is for a range of different voltage relays. Yours is the 4.5V one. If you're worried about it the either use the 5V version or stick a resistot or diode in series with it.

Mike.

I was thinking the same thing, o use a diode in series. Can I use LED instead of normal diode?

 

[Pommie]

A diode will drop about 0.6V giving you ~4.5V for the relay. An LED will drop 2V so not really usable. If you're really worried why not swap it for a 5V one?

Mike.

 

[smilem]

A diode will drop about 0.6V giving you ~4.5V for the relay. An LED will drop 2V so not really usable. If you're really worried why not swap it for a 5V one?

Mike.

Because the device has 21 relay. The cost for single relay is about 2.50 - 3.50Eur. The whole device costs 99Eur. To change relays would cost 52 - 73Eur. So changing relays is not an option. I wonder how much less will they work compared to 5V?

 

[Pommie]

From the datasheet, power at 4.5V is 140mW. 5V is about 20% more power so about 170mW. Temperature table says this will be 25C over nominal. As long as your not running this in a very hot sauna it should be fine. In fact there's a table for over voltage which suggests no problem at 6.75V up to 40C ambient.

Mike.

 

[Nigel Goodwin]

Running 4.5V relays at 5V is no issue whatsoever, don't worry about it.

 

[dr pepper]

Run it for a while then see if it warms up.

 

[gophert]

Because the device has 21 relay. The cost for single relay is about 2.50 - 3.50Eur. The whole device costs 99Eur. To change relays would cost 52 - 73Eur. So changing relays is not an option. I wonder how much less will they work compared to 5V?

Three days less.

 

[Visitor]