# Solid State Relay

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##### New Member
Hello, I am working on a 12V control board that will have a normal 30A relay, but the others one must be a fast switching that can handle switching serval times before stopping (so I think I need a solid state device that can handle i), they will be controlled by a 5V AVR chip. The Solid State device needs to able to handle at least 3A. The control board will be mounted in a car once completed. Can anyone help me with this...

Shane

#### Papabravo

##### Well-Known Member
I'm not sure what you are asking for help with. You seem to have your requirements nailed down. Are you asking for suggestions on components that might meet those requirements? If so the best thing to do is troll the manufacturers websites.

NEC makes relays
OMRON makes relays
check Digikey
check Mouser

All four places have selection guides that will help you make up your mind. The good thing about starting with online distributors is that you can get a pretty good idea of the part's availability.

#### ericgibbs

##### Well-Known Member
Hello, I am working on a 12V control board that will have a normal 30A relay, but the others one must be a fast switching that can handle switching serval times before stopping (so I think I need a solid state device that can handle i), they will be controlled by a 5V AVR chip. The Solid State device needs to able to handle at least 3A. The control board will be mounted in a car once completed. Can anyone help me with this...

Shane
Hi Shane,
What switching speeds/rates are you expecting on the project.?
If the VN05 are too pricey, relays may be the second option.

##### New Member
Well like the whelen, it needs to be less than a second, maybe 500ms or something like that to change the pattern. It would destroy a normal relay, so that why I need something that is solid state. I was hoping that I could find something with very low RDS like the VN820 (40m ohms), but I don't think it handles TTL signals. Ain't 40m ohms lower than 0.18 ohms correct? I want to try and keep them cooled as much as possible. I was hoping to find dual or quad types, but their RDS seems high.

ericgibbs said:
Hi Shane,
What switching speeds/rates are you expecting on the project.?
If the VN05 are too pricey, relays may be the second option.

#### ericgibbs

##### Well-Known Member
Well like the whelen, it needs to be less than a second, maybe 500ms or something like that to change the pattern. It would destroy a normal relay, so that why I need something that is solid state. I was hoping that I could find something with very low RDS like the VN820 (40m ohms), but I don't think it handles TTL signals. Ain't 40m ohms lower than 0.18 ohms correct? I want to try and keep them cooled as much as possible. I was hoping to find dual or quad types, but their RDS seems high.
40millihm: = 0.040hm: ..... 0.18hm: = 180millihm:

You can level shift the MCU drive signals by using an intermediate BJT transistor or small FET.

##### New Member
OK, i got the samples today and noticed that the dual channel version has about 20 ohms extra than the signal one. I thinking about using the dual channel instead of the single, so my question is that the dual channel draws 200m ohms, how much watt and amp is that? Is there any extra protection that I should addd to them?

PS: Do I need a heatsink if I going to run these dual channel version to 6A for both channel? Which one do I need?

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