Npn Power
Max voltage at the base of a transistor?
I’m using a BU2520DF as a switch..it’s a NPN power transistor, and i’m wondering what is considered to be a typical “max” base voltage for a BJT…i’ve looked at the datasheet for this, and the graph for base voltage only goes to 1.4 volts if i remember right…problem is i don’t have a supply that goes that low..the lowest supply voltage i got is 12v. if i could post the schematic i’m using i would, but suffice it to say that i am using a mosfet to switch a power supply where the +12v is connected to the drain, and the transistor’s base is connected to the source with a 60 ohm resistor in series….am i gonna blow out the transistor?? i’ve never really heard of a max base voltage before, unlike in a mosfet where the typical max gate voltage is +/- 20v.
VBE is usually about 0.6 to 0.7 volts.
You do NOT apply a fixed voltage to the base (I’m assuming common emitter). The base is a current device, like a forward biased diode, and should be driven by a current, not a voltage. In your case, you have 12 volts and 60 ohms, which is a current of about 180 mA, a bit high, but OK for a power device.
Checking, this part has a built in 50 ohm resistor B to E, which changes things. It limits the gain severely.
You can email me if you want more help.
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