Lecture 15, Slide 1
EECS40, Fall 2003
Prof. King
Lecture #15
ANNOUNCEMENTS
• Prof. King’s office hour today is cancelled
• Farhana’s office hours this week are cancelled
• HW#5 will be available on Friday 10/3 (due 10/10)
• Pick up graded midterms in discussion sections
OUTLINE
– Transient response of 1
st
order circuits
– Application: modeling of digital logic gate
Reading
Chapter 7.37.5
(with Prof. Sanders)
Lecture 15, Slide 2
EECS40, Fall 2003
Prof. King
Transient Response of 1
st
Order Circuits
• In Lectures 13 and 14, we saw that the currents and
voltages in RL and RC circuits decay exponentially with
time, with a characteristic time constant
τ
, when an
applied current or voltage is suddenly removed.
• In general, when an applied current or voltage suddenly
changes, the voltages and currents in an RL or RC
circuit will change exponentially with time, from their
initial values to their final values, with the characteristic
time constant
τ
:
where
x
(
t
)
is the circuit variable (voltage or current)
x
f
is the final value of the circuit variable
t
0
is the time at which the change occurs
[]
τ
/
)
(
0
0
)
(
)
(
+
−
−
+
−
+
=
t
t
f
f
e
x
t
x
x
t
x
This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentLecture 15, Slide 3
EECS40, Fall 2003
Prof. King
Procedure for Finding Transient Response
1. Identify the variable of interest
•
For RL circuits, it is usually the inductor current
i
L
(
t
)
•
For RC circuits, it is usually the capacitor voltage
v
c
(
t
)
2. Determine the initial value (at
t
=
t
0
+
) of the
variable
•
Recall that
i
L
(
t
)
and
v
c
(
t
)
are continuous variables:
i
L
(
t
0
+
) =
i
L
(
t
0
−
)
and
v
c
(
t
0
+
) =
v
c
(
t
0
−
)
•
This is the end of the preview.
Sign up
to
access the rest of the document.
 Fall '08
 ChangHasnain
 RC circuit, RL circuit, Prof. King

Click to edit the document details