Mosfet won't turn off completely (Gate tied to GND)

[24602]

Hey All

Got some VNB14NV04 N channel mostfets connected up to some 12v (testing also with 24V) LED strips, super simple stuff.

But noticed when setting the LEDs to 0% they're still glowing. Thought it was my driver but I connected the Gate directly to LED Supply GND and the same occurs.

Confused as the I'm using the same mosfets as another product that works just fine with identical driver etc.

Ive pinched a photo/schematic showing what I have setup initially just change R1 to 10K and R2 to 47R and add a mosfet driver. But at the moment removed everything from the gate and connected it directly to GND.

Swapped out the mosfet incase I somehow blew the first one up.

Anything I have completely missed?

 

[uer166]

What is the current through the glowing strip? Datasheet specifies 25uA leakage at 70C which may be enough to make some high efficiency LEDs visible.

[24602]

Yeah that could be it - getting 11.2uA @ 24V

Where did you find the leakage current? - just scanned through the data sheet and couldn't find it again 

Just odd as an existing board with the same mosfet connected up the same way has no sign of leakage. I'll  have to hook it back up and measure if there's any leakage.

[ataradov]

This datasheet https://www.infineon.com/dgdl/irlml2502pbf.pdf?fileId=5546d462533600a401535668048e2606 Search for "Drain-to-Source Leakage Current".

And yes, modern LEDs are stupid efficient.

[24602]

ataradov - But that data sheet isn't for my part? 

[ataradov]

But that's the part on the picture.

In your datasheet this parameter is called "Zero input voltage drain current" (I_DSS). And it is 30 uA for your conditions.

[BrianHG]

ataradov - But that data sheet isn't for my part? 

Even worse leakage current.

[24602]

But that's the part on the picture.

In your datasheet this parameter is called "Zero input voltage drain current" (I_DSS). And it is 30 uA for your conditions.

Yeah I can see why that was confusing, I have removed the image, My part is VNB14NV04

[viperidae]

Maybe putting a 100k resistor in parallel with the LEDs would drop the voltage across them enough so they don't turn on.

[24602]

Maybe putting a 100k resistor in parallel with the LEDs would drop the voltage across them enough so they don't turn on.

Worked straight way  Thanks!