Help regarding selection of 5 volt cutoff device

[shank047]

Hi , i am a kind of newbie to the electronics .
I wanted to know if any specific power electronic or just a regular diode is available so that it can cutoff 5-6 volts dc supply.
Particularly i want this device to send no current between 0 to 5 volts , but only to start conducting after reaching 5 volts + value.

Is there any zener diode with 5 v cutoff available ? If so can anyone suggest the IC number or so.

 

[barry]

1N5338 is a 5.1volt zener. What are you really trying to do? How much current do you need? A zener might work, but it's not a linear device.

 

[mister_rf]

You can use this circuit:

 

[shank047]

well i am trying to build a switch using power mosfet and a microcontroller which can turn on only when the voltage is beyond 5 volts. (max voltage will be 6 volts i think )
For this my zener diode will act as an indicator , which when connected to an ADC , will send an signal to mc . (well use of mc is very important as i have to perform additional tasks using this mc kit ). MC in turn will send in gate vltg to the mosfet for turning it on.

i am attaching a basic block diag representing d ckt

 

[mister_rf]

If you are using ACD, no need for the zener diode.
You may use a voltage divider (two resistors in series) on the ADC input and let the microcontroller to compare the ADC output data with a preset value to decide when to shutdown power…

 

[shank047]

If you are using ACD, no need for the zener diode.
You may use a voltage divider (two resistors in series) on the ADC input and let the microcontroller to compare the ADC output data with a preset value to decide when to shutdown power…

ok.
then according to my above ckt diag , am i going correctly ?( except the use of zener diode of course )
Do i need to make any more changes to it, like a use of an DAC between mc and the gate terminal of mosfet ? I think so 'coz the mc will b sending out digital signals , so will it be enough to control the gate terminal vltg.?

 

[dselec]

Seems u building a Mercedes to go to the local shop to buy beer .
Why not build a simple comparator ( with a resistor and 5v zener diode) that will switch on a mosfet or relay that will supply the load . if u must use mpu cause there is another reason then shank idea is perfect

 

[mister_rf]

No need to use DAC. :smile:
Simply connect the port to a bipolar transistor, see details here:

 

[shank047]

Thanx.
I think that will do the trick for me