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How are the characteristics of an NPN transistor calculated?
The actual position of the load line on the characteristics curves can be calculated as follows: Then, the collector or output characteristics curves for Common Emitter NPN Transistors can be used to predict the Collector current, Ic, when given Vce and the Base current, Ib.
How to calculate base and emitter current in a transistor?
Transistor Current Calculation Base current ( IB ) hfe or β Collector current IC = mA Emitter Current IE = mA Transistor Base Resistor Calculation Base Voltage hfe or β Base – Emitter Voltage Base current IB = mA Resistor RB = kΩ Supply Voltage Resistor RC Collector current
What should the base resistor be for a bipolar transistor?
For hard saturation, engineers usually choose a value of 10. Remember that a bipolar transistor is a current amplifier, because a small amount of current “Ib” through the base controls a larger amount of current “Ic” flowing through its collector.
What’s the maximum collector rating of a transistor?
Usually, a general-purpose transistor such as the PN2222 has maximum collector rating (Ic) of 600-mA DC. If your load requires more current, then it is common sense to consider transistors with a larger Ic rating.
Is the collector current independent of the base voltage?
For the usual collector-emitter voltage drops (i.e., the active region : positive voltages from a fraction of a volt up to some breakdown voltage) the collector current ( IC) is nearly independent of the collector-emitter voltage ( VCE ), and instead depends on the base current ( IB ).
What is the formula for transistor VBE IC?
Below is NPN BJT transistor Vbe Ic characteristics and the formula: Many texts approximate this equation as: Ic = Is*e^(Vbe/Ut) and following this they say when Vbe=0, Ic becomes equal to Is. Stack Exchange Network
What are the properties of a bipolar junction transistor?
One of the most important properties of the Bipolar Junction Transistor is that a small base current can control a much larger collector current. Consider the following example. A bipolar NPN transistor has a DC current gain, ( Beta) value of 200. Calculate the base current Ib required to switch a resistive load of 4mA.
What makes a bipolar NPN transistor a good amplifying device?
The value of β can be large up to 200 for standard transistors, and it is this large ratio between Ic and Ib that makes the bipolar NPN transistor a useful amplifying device when used in its active region as Ib provides the input and Ic provides the output. Note that Beta has no units as it is a ratio.
What is the relationship between base and emitter in NPN?
The voltage between the Base and Emitter ( VBE ), is positive at the Base and negative at the Emitter because for an NPN transistor, the Base terminal is always positive with respect to the Emitter. Also the Collector supply voltage is positive with respect to the Emitter ( VCE ).