Output drivers

roger · Guest

Hi All,

Does anyone know the the advantages or disadvantages of using:

ULN2803 (Darlington driver IC) vs Relays??

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If a solenoid is rated as using 1A, is it good practice to double this
current, due to it being an inductive device???

I hope someone can help

mvaraujo · Joined: 20 Feb 2004 Posts: 59 Location: Brazil

Roger,

It really depends on what you're driving. If you're driving inductive load that could generate noise in the switching, if would use relay and keep separated power. But keep in mind that the relay is much slower than a solid state device, so again, it depends on what you're driving.

Marcus

roger · Guest

thanks,

I am thinking of driving

Electric Valve (solenoid based)

dyeatman · Joined: 06 Sep 2003 Posts: 1934 Location: Norman, OK

I use the ULN2803 extensively but make sure my overall current level is well below 500ma to avoid temp problems.

The main advantage to relays is the multiple contacts and being able to switch AC or DC as required. Many times I use the ULN2803 to control a PC relay.

Using the ULN2803 to drive a relay provides a buffer/driver to protect the processor and so I socket all of mine. That saved me several times. I have been able to simply replace the chip ($0.50 each) when it goes and everyting else is protected. That being said I buy them 50 at a time and use them in all my outside world driver applications.

... · Guest

Hi

You can search at google.com about "PhotoMOS" this is an optically isolated switches and they can act fast.

I use this in one of the project I have in replace with Relay.

Hope this helps.