When I thought about it I realized that this effect stems from the "thermal resistance" of the ambient air.
January 1, Base Drive Circuits: It is good to know about Power transistor basics, Characteristics and Construction before proceeding further.
The main application of power BJT is behave as a static switch in the power electronics circuits. Click here to know about the Basics of Power Transistor.
This stored charge must be removed. The following figure shows the simple base drive circuit which may be used to provide a suitable drive. The circuit is driven from a voltage source which switches between 0 and V volts.
Saturation of the device should be avoided to ensure the fast switching. We can achieve this by using Baker's clamp. The diode D2 provides an offset voltage to allow for the voltage drop across D1.
Following are the important points about BJT to be remembered when designing the base drive circuit for the transistor.
BJT is a current controlled device. Its operation is controlled by the base current. Power BJT operates in saturation and cutoff region when used as a switch.
Sufficient base current is required to drive BJT in saturation. Amount of carrier injected in base region determine storage time of BJT.
Storage time determines turn-on and turn-off times of the transistor. There should be mechanism to control the amount of saturation so as to control storage time.Browse Diodes Incorporated's line of MOSFET plus BJT to find products with twice the capabilities.
Analysis of the role of the parasitic BJT of Super-Junction power MOSFET under TLP stress Author links open overlay panel T. Chirilă a b c W. Kaindl b T. Reimann c M. Rüb a U. Wahl b Show more. BJT has negative temperature coefficient, so current-sharing resistors are mandatory during parallel operation of BJTs.
Secondary Breakdown Issue: (iv) The major difference between Power-MOSFET and Power-BJT is, that the Power-MOSFET do not have the secondary breakdown problem whereas Power-BJT suffers from secondary breakdown issue. BJT is the acronym for Bipolar Junction Transistor, FET stands for Field Effect Transistor and MOSFET is Metal Oxide Semiconductor Field Effect Transistor.
All three have several subtypes, and unlike passive semiconductor devices such as diodes, active semiconductor devices allow a greater degree of control over their functioning.
operation of the BJT. The equivalent circuit in (a) represents the BJT as a voltage-controlled current source (a transconductance amplifier) and that in (b) represents the BJT as a current-controlled current source (a current amplifier). Whenever we observe the terminals of a BJT and see that the emitter-base junction is not at least volts, the transistor is in the cutoff region.
In cutoff, the transistor appears as an open circuit.