looking for BJT that inludes protection diode.

[alphadog]

I have a BJT that switches on & off a relay, and i couldnt find a low cost, not through hole, BJT with protection diode included.

Does anyone know about some?

Thank you.

Addition:
I forgot to mention that i'm interested in an NPN BJT.
Thanks.

 

[mneary]

Check in Digikey for transistors, and sort on transistors, single bjt. Scroll to the right and find the selection for NPN+diode. (and check 'in-stock').

Looks like there are a few to choose from starting at 56 cents.

 

[alphadog]

Thank you.
Everything thats on stock there is transistors array, not single.

 

[Nigel Goodwin]

Why on earth do you want one?, protection diodes need to really go across the relay, NOT across the transistor - just use a separate diode across the relay.

 

[blueroomelectronics]

Since it's probably for a 4 transistor h-bridge the diodes will work.

 

[Nigel Goodwin]

Since it's probably for a 4 transistor h-bridge the diodes will work.

Except he specified an NPN transistor (singular) and a relay.

 

[blueroomelectronics]

Ah yes, silly me thought it was a continuation of the latching coil thread.

 

[alphadog]

I have a question please, not related to BJT and relay.
I found a N-channel MOSFET that has a diode across its Drain-Source channel.
If the VGS is lower than VTO, then IDS should be zero and therefore VDS becomes VCC (assuming its source's connected to VCC).
In my case, VCC = 5V which is larger than the VF of the Drain-Source diode.
How come the diode doesnt start coduncting current and therefore increasing IDS from 0A to IF of the diode?

Thanks.

 

[mneary]

Because the diode is reverse biased.

 

[alphadog]

Because the diode is reverse biased.

Thats the thing, the anode is connected to drain, not to source, so its forward biased.

Take a look please:

 

[mneary]

That's a dual transistor, one N-channel and the other P-channel. The drain of the P-channel device (Q2) is connected to the anode of its diode.

The drain of the N-channel device (Q1) is connected to the cathode of its diode.