Semester 2 Flashcards
weaknesses of an mechanical switch
wears out and limited speed
difference between latching and non-latching electrical switches
latching use a signal applied to an electrode and then remain switched on
for non latching the control signal must reamin on for the duration of the on period
advantages of electrical switches
- Lossless (ideal case)
- High frequency
- No moving parts
- Cheap
limittions of solid state switches
- Maximum current rating
- Maximum voltage rating
- Turn-on and turn-off switching transition times
- Maximum power dissipation
can arbitrarily decide to turn off a latching switch
no
what are most latching and non latching switches used for
latching - AC
non latching -DC
applications of latching switches
light dimming and motor control
what is the rough number of valence electrons of a semiconductor
3-5
what is n-type doping
the donor impuritie contributes free electrons
what is p-type doping
the cceptor impurity creates electron holes
what is the p-n junction
the area at which no current flows - widely the greater V needed
what are the 3 parts of a bipolar junction transsitor
collector, emitter, base
as Ib rises how does Ic rise
it rises linearly by Beta until it reaches the saturation current
at cut off how does the transistor behave
like an open switch
most common semiconductor
silicon
what happens when the electric field is connected in the same diection of the depletion zone
it grows the zone to behave like an insulator
why is a cureent put through the base
reducing the potential difference to the top reducing the depletion zone
can diode’s change current instantaneously
no
Icsat=
(Vcc-Vce)/Rl
Ibsat=
Icsat/Beta
advantages and disadvantages of overdriving
Speeds up the turn-on process and reduces switching losses
Slows down the turn-off process
why is overdriving done
to ensure saturation is acheived
reverse recovery tie is proportional to
base current
what happens in reverse recovery mode
a pulse of base current and the BJT remains on
