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F it . 3·5. An optrl ll on•l mode l of • PNP wi th • s witch (5)
connec ted from bue to tround . In 1c tual clrc uila the • • •tch
may be enother transla tor .
F ig. l ·IA . T he opt rlllonal chlrac lerlat lca of • trans ls tOf
s witch . Note the ltss · than ·ldul charac ter la t lc s 11 A 1nd B.
F lq , 1·68 . The operallon•l c hlflcterlatlcs of lht uturatlon
reg•on . Poi nt A Is the .. me u point A In F ig . l ·IA .
B on curve 3-6A. The portion of
the curves below the curve Ia = 0
is termed the cutoff region. Note
that when operated at the cutoff
region, a small current still flows
in the collector current . Again the
resistor switch exhibits less-than-
ideal characteristics .
Should the transition from the
saturation region to the cutoff
region (or vice versa) be halted ,
say at point Con figure 3-6A , the
transistor would be operating in
the active region . In this case the
voltage across the transistor VeE
would be - 3V also, the collector
current lc would be - 20ma .
Any point on the load line be-
tween points A and B is in the
active region. The active region is
of little, if any concern to the
digital circuit designer since it
belongs in the realm of linear
circuits. Because digital circuits
operate in either the saturation or
cutoff regions , points A and Bare
of primary concern .
When a transistor is operated in
the saturation region , it is said to
be saturated or on; and when
operated in the cutoff region , it is
•
said to be cutoff or off.
4
12
PROGRAMMED TEST,
LESSON THREE
Again, start at block one and follow
the numbered instruction associated
with your answer
1
YOU ARE CORREC T!
When all of the power supply voltage is
across the transistor, the trans istor is
operating in the - - - - - - - - -
a. Saturation reg ion
GO TO BLOCK 10
b. Cutoff reg ion
GO TO BLOCK 22
Whttt ' ' V c £ . the v01t1ge across R c and l c ar poutt 0 on
hg. 3·6A,
End of Lesson Three
YOU ARE INCORREC T!
Refer to the text and return to BLOCK 1.
13
YOU ARE CORRECT!
The c urrent generator produces a cu;rent
f3
5
x I a
YOU ARE INCORREC T!
whe n the base-emitter diode is
Refer to the text and return to BLOCK 22.
a. Forward biased
6
b.
GO TO BLO CK 3
YOU ARE INCORRECT!
Reverse biased
GO TO BLOCK 21
Refer to the text and return to BLOCK 15.
7
14
Refe r to the text and return to BLOCK 3.
When operating in the saturation reg ion ,
there is a small voltage drop across the
transistor. Th is voltage is termed
B.
The model shown in the figure is that of
a/an
_ _ _ _ _ _ _ _ _ _ transistor.
a. PNP
GO TO BLOCK 12
b. NPN
GO TO BLOCK 20
b.
2
8
YOU ARE INCORRECT!
Refer to the text and return to BLOCK 20
3
15
YOU ARE CORREC T!
GO TO BLOCK 17
When the transistor is opera ting in the
satura tion region, l c is determined by_
GO TO BLOCK 24
a. beta times Ia
V CE(sat )
Ve E
GO TO BLO CK 6
b.
V ee
and Rc
GO TO BLO CK 23
YOU ARE CORRECT and have
completed the test for the th ird lesson .
However, you should review the concepts
of this lesson . Future lessons will assume
you understand th is subject matter.
Refer to the text and return to BLO CK 23.
10
17
16
YOU ARE INCORRECT!
YOU ARE CORRECT!
The current f3 x I 8 is the
a. Base current
GO TO BLOCK 14
b. Collector current
GO TO BLOCK 25
12
YOU ARE INCORREC T!
YOU ARE CORRECT!
YOU ARE INCORREC T!
Refer to the text and return to BLOCK 4
11
YOU ARE INCORRECT!
Refer to the text and return to BLOCK 25
YOU ARE CORRECT!
Digi ta l circui ts operate between the __
reg ion and the
region.
a. Saturation /cutoff
GO TO BLO CK 8
b. Acti ve /cutoff
GO TO BLOCK 19
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