Hi,

Please confirm below attached circuit works or not ?
3.3V From controller.

Thanks,
Ashok

 

Make it easier for us to help you. Attach the datasheet or tell us what the Vth of the device is.

 

hi ashok,
It will work but the resistor value is much too high, try a 1k
E

 

Hello,

The mosfet is huge for the used schematic.

Bertus

 

The mosfet is huge for the used schematic.

+1. Extreme over design.


The circuit will work, but anyone looking at it will be wondering why that MOSFET was chosen.

 

Hi,

Please confirm below attached circuit works or not ?
3.3V From controller.

Thanks,
Ashok

View attachment 159403

You need to better define what it means for it to work?

If, by "work", you mean that a signal that goes from 0 V to 3.3 V will have change the amount of current going through the LED, then it will work.

But if, by "work", you mean that it will get enough current through the LED in order for it to be perceptibly lit, you haven't given us enough information.

Assuming your MOSFET switch works ideally and you get the full 12 V across the LED/resistor and assuming your LED drops 2 V, then your current is going to be about 830 μA. Is that enough to light up the LED well enough for your purposes? We have no way of even estimating that since some LEDs work will at currents even less than that while many require significantly more.

 

Hello,

The mosfet is huge for the used schematic.

Bertus

Hi,
Thanks for your Suggestion.and suggest me a mosfet which is suitable for our Application.
Thanks,
Ashok

 

+1. Extreme over design.
View attachment 159407

The circuit will work, but anyone looking at it will be wondering why that MOSFET was chosen.

It has a threshold voltage that can be as high as 2.5 V. The microcontroller output can probably be as low as about 3.0 V due to supply tolerance (and even lower and meet logic family specs). That doesn't give a lot of overdrive, but this transistor doesn't need much to get the kind of currents involved here to flow. Also, it looks like the input capacitance is pretty hefty at around 10 nF. That might come into play if it needs to switch quickly.

 

You need to better define what it means for it to work?

If, by "work", you mean that a signal that goes from 0 V to 3.3 V will have change the amount of current going through the LED, then it will work.

But if, by "work", you mean that it will get enough current through the LED in order for it to be perceptibly lit, you haven't given us enough information.

Assuming your MOSFET switch works ideally and you get the full 12 V across the LED/resistor and assuming your LED drops 2 V, then your current is going to be about 830 μA. Is that enough to light up the LED well enough for your purposes? We have no way of even estimating that since some LEDs work will at currents even less than that while many require significantly more.

Hi,
I Designed this circuit for to confirm the 12v Available or not.
Thanks,
Ashok

 

Hi,
suggest me a mosfet which is suitable for our Application.

What is the LED you're using? Do you have its datasheet?

 

Hello,

If you want to use a mosfet, the tiny Si2300DS might do the job.

Bertus

 

Hi,
I Designed this circuit for to confirm the 12v Available or not.
Thanks,
Ashok

That doesn't help much.

HOW does this circuit confirm that 12 V is available? By lighting up the LED? If so, then everything I said still applies. You are going to have less than a milliamp flowing in the LED. Is that enough to make it light up sufficiently in order for you to determine that 12 V is available?

 

For your application then you can try 2N7000, when the Vgs=3.3V then the Ids could provides >80mA (If the figure 5 on page 5 is correct).
Led = 2V/20mA, R = 610Ω(16.4mA), Vds = Ids*Rds = 16.4mA * 1.2Ω ≅ 0.020V when Vgs ≥ 3V.
Led = 3V/20mA, R = 560Ω(16mA), Vds = Ids*Rds = 16.mA * 1.2Ω ≅ 0.0192V when Vgs ≥ 3V.

 

What is the LED you're using? Do you have its datasheet?

Hi ,
Please find the Attached Led Datasheet.
Part Number-LTST-C193TGKT-5A
Thanks,
Ashok

 

hi ashok,
If the LED is to indicate the state of the 12V line, why not just a 1k in series with an LED.?
What is the purpose of the MOSFET, there is no obvious feedback from the FET , other than the observers eye.??
If the MCU output pin is not at 3.3V ie: 0v , would that mean the 12V line is 0v.???

E

 

Hi All,

Based on all your Suggestion.I changed design.Below attached the updated design.please confirm.


Thanks,
Ashok

 

You still didn't say that why you want to using the MOSFET to drive the LED, if only to do the indicator, maybe you can only use the LED with a small resistor and connected to the digital output of uC.