DC solid state relay , how to make cheaply

[Electro nS]

i have tried to use a AC solid state relay to connect / disconnect a DC load. with failure due to zero crossing ....etc..

i have searched the internet and the prices of DC relays (mosfets instead of traics..or thyristors) are quite expensive !

So why not build my own !?? after all it is just a mosfet , driver and some logic , right ?

any ideas ?

note : The load is DC 12-48 , current around 50A continous . this relay is used as the power supply switch (ON/OFF), instead of using HUGE electromechnical relay or switches .

my basic idea is to use N MOS with half bridge driver , or a P-MOS (although it is quite hard to find good ones with low RDSon) on the HIGH side

or use N MOS without driver on the lower side ( to disconnect GND instead of VCC to the load ) , but i donot know if keep the load floating is that OK ??

please share any experience or ideas , i would appreaciate

thanks :-o

 

[D.A.(Tony)Stewart]

I might suggest https://www.digikey.com/product-detail/en/IXFN230N20T/IXFN230N20T-ND/2126317 switch with suitable 1~2A driver. The transition time needs to be fast to prevent power dissipation in switch. Then filtering is needed to prevent EMI radiation.