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What does it mean when a transistor is saturated?
Saturation is the on mode of a transistor. A transistor in saturation mode acts like a short circuit between collector and emitter. In saturation mode both of the “diodes” in the transistor are forward biased. That means VBE must be greater than 0, and so must VBC. In other words, VB must be higher than both VE and VC.
At what voltage does a transistor saturate?
“Saturation” in a transistor switch circuit is achieved when the voltage across the collector/ emitter (VCE(sat)) is less than or equal to . 1 to . 3 volts – depending on the type of transistor. At that voltage point, the transistor appears to act like a simple SPST mechanical switch that has been closed (On).
When a junction transistor is operated under saturated condition?
When a transistor is operated in a saturation region, the emitter and the collector terminals are at higher potential. When the anode terminal of a junction diode is at higher potential than that of the cathode, the junction diode is said to be forward biased.
What may cause a transistor to fail?
Failures can be caused by excess temperature, excess current or voltage, ionizing radiation, mechanical shock, stress or impact, and many other causes. In semiconductor devices, problems in the device package may cause failures due to contamination, mechanical stress of the device, or open or short circuits.
When does a transistor go into saturation what happens?
A transistor goes into saturation when both the base-emitter and base-collector junctions are forward biased, basically. So if the collector voltage drops below the base voltage, and the emitter voltage is below the base voltage, then the transistor is in saturation.
When is the base resistor in hard saturation?
Your circuit might be TTL and feeding 5-V, or perhaps CMOS, feeding 3.3-V. In this example, to make the maths simple, let us say that the switching voltage is 10-V at the input. When the transistor is in hard saturation, the entire switching voltage (10-V), will be effectively across the base resistor.
Why does the base current of a transistor not increase?
The transistor wants its collector current to increase, because its base current is continuing to increase, but it can’t, because the collector circuit is limiting the current. Or another way to put it is that the transistor is running out of collector-emitter voltage.
What happens to the base current at saturation?
At this point, the base current is maximum and so is the collector current. At saturation, collector-base junction no longer remains reverse biased and normal transistor action is lost. If base current is greater than IB ( sat ), then collector current cannot increase because collector-base junction is no longer reverse-biased.