voltage gate circuit... help!

[Mordor]

Hi, for a project i need to make a protection circuit.
Input can be from 1 to 65 70 volt.
Output must be on from 20.5 to 56.5 ( with mosfet always in saturation or closed, not in half state) taking out lower voltages and higher voltages... a voltage band pass gate with 1 ampere max.
I played with mosfet and zener, the way is right.
Some idea about a simple des for it ? thank!

 

[gmphadte]

Use a window comparator. Attenuate the voltage to the required levels if u use the IC comparator/opamp in the circuit.

Gajanan Phadte

 

[Mordor]

i was trying to use resistors zeners and mosfet in order to make this in a simple and discrete way ... opamp? so u mean use a normal op amp with zener resistor for supply, and partitor for compare values ?

 

[grommeteer]

LTC4366 not exactly what you need. You might be able to build something around it.

 

[nigelwright7557]

Being a PIC man I always use a small PIC to monitor the output voltage for DC.
If DC is detected for 500mS the PIC turns off the output relay.
The same PIC also has a 3 second power up delay before turning on the relay.
It can be done with an 8 pin PIC very easily.

 

[tauro0221]

Hi,
I think this is what are you looking. Check this link:Voltage Comparator Switch

 

[gootee]

Maybe some of the circuits used to protect against automotive load dump would work for you. Try google.