![]() Also, the large the base, the lower the base resistance, so less voltage drop across the base resistance. so the higher the hfe, the lower the Vbe. The higher the hfe, the smaller the current at a given Ie. Concept explainers Given the following circuit, if V79V, R1128, R2331 and R3215 Find the value of the voltage drop across resistor R3 Find the value. ![]() Collector Emitter Saturation Voltage VCE (Sat) - V 0.25 0.60 Base Emitter On Voltage VBE (on) IC 2mA, VCE 5V IC 10mA, VCE 5V 0.55-0.70 0.77. Any current through the base resistance with create a voltage that adds to the Vbe. Collector-Emitter Voltage VCEO 45 25 Collector-Base Voltage CBO 50 30V Emitter-Base Voltage VEBO 6.0 5.0 Collector Current Continuous IC 0.2 A Power Dissipation at Ta 25☌. So by definition, larger the transistor, the lower the Vbe.Īs for hfe, think of it this way, there is always a parasitic base resistance in series from the pin to the base inside. 100 transistor will reduce by 120mV.and so on. But why doesnt Vce become zero As far as I know: when the transistor is saturated, the. If you have 10 transistors in parallel, using the same equation will give you a reduction of 60mV. Below is an NPN transistor symbol and the voltages at its terminals are Vb, Vc and Ve with respect to the ground: I read that: during the saturation the Vce (Vc-Ve) settles to around 0.2V and the further increase in base current will not make Vce zero. If you calculate for two transistor where each contribute half, the equation gives 18mV reduction in Vbe. This is what I know about NPN BJTs (Bipolar Junction Transistors): The Base-Emitter current is amplified HFE times at Collector-Emitter, so that Ice Ibe HFE Vbe is the voltage between Base-Emitter, and, like any diode, is usually around 0,65V. Collector-Emitter Saturation Voltage VCE(sat)1 IC10mA, IB1mA - 0.2 V VCE(sat)2 IC50mA, IB5mA - 0.3 Base-Emitter Saturation Voltage VBE(sat)1 IC10mA, IB1mA 0.65 - 0.85 V VBE(sat)2 IC50mA, IB5mA - 0.95 Transition Frequency fT VCE20V, IC10mA, f100MHz 300 - MHz Collector. CollectorEmitter Voltage VCEO 40 Vdc CollectorBase Voltage VCBO 60 Vdc EmitterBase Voltage VEBO 6.0 Vdc Collector Current Continuous IC 200 mAdc Total Device Dissipation TA 25☌ Derate above 25☌ PD 625 5.0 mW mW/☌ Total Device Dissipation T C 25☌ Derate above 25☌ PD 1. ![]() If you think of it that way, for two transistors, each will contribute only half the current.įrom equation \delta V be= V T ln(I 1/I 2). It's like many transistors in parallel together. If you look under the microscope, the power transistors have emitter like fingers extending out to cover more area. For a given Ie, Vbe is lower for larger transistor for very simple reason, The large transistor is like a bunch of small transistors in parallel.
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