Why do we need to look into hFE

[nikhillife11]

Hello All,

I am trying to work with M34063 with 2SB1386 transistor for stability. There is a lot circuit diagram about these combination on internet. What I want to ask is, Initially when i brought the transistor 2SB1386, its was 2SB1386Q i.e. hFE range 120 t0 270. Now i am not able to find the same, What i got is 2SB1386R. When i checked the datasheet it said for 2SB1386R, hFE range is 180 to 390. Can anyone help me with this problem.Can I use 2SB1386R for my circuit. How can I find whether it will suit my circuit.
Please help.... I am designing the circuit for and output of 3.3V/1.5A with input being 18V.

Thanks and Regards

Nikhil

 

[mister_rf]

Your particular transistor is available in various gain bands, but no problem in this case, you may use it without any changes. In general make sure the base current is more than enough to overdrive. For this you need to know the minimum current gain for the sort of current levels involved. Using a large gain will guarantee transistor saturation.

 

[nikhillife11]

hello Mister_rf,

Using a large gain will guarantee transistor saturation.

What do you mean by above..Can you make it a bit clear for me...Also how can I find the base current needed to drive this transistor...

Please Help....

Thanks & Regards

Nikhil

 

[mister_rf]

So let us know what’s the schematics are you using for.

 

[siongboon]

For any electronic components, we can see Tons and Tons of parameter in the datasheet.
hFE is only one of the parameters.
Depending on the circuit that you are designing, we usually look at a few specification that will be important for our design.
Not all parameters are important. For me, I usually use transistor to operate as a switch, hFE is usually not my concern.
So it really depends on your application, what you are designing it for.