MOSFET SSRelay (LCA717) connected to Arduino Digital Pin

Thread Starter


Joined Mar 20, 2009
I am trying to figure out how to go about using this LCA717 SPST-NO relay in my project. I will be sending 12V (car voltage) to a radar detector and I want to be able to turn it on/off whenever via the Digital Pin on an Arduino board (max 5V output).

As in, when the digital pin is high it allows 12v to flow to the radar. When the digital pin is low then it shuts out the 12V so no power is going to the radar.

But the problem is that I have no idea what to use for pin 5? Or if pin 4 and 6 are the correct pins to use to do what I am looking to do above?

The LCA717 PDF is$file/LCA717.pdf

The radar detector has a MAX amp of 2. Will the LCA717 need a heatsink? I have heard that since the On-State Resistance is 150 mOhm that it will need one?


Joined Mar 14, 2008
For a DC load you use the "DC Only Configuration" since it puts the two MOSFETs in parallel, reducing the ON resistance to 0.04Ω maximum. That gives a maximum ON dissipation of 2^2 * 0.04 = 160mW @ 2A, which is well below the 800mW maximum rating at 25°C, so you don't need a heat-sink.