clc436 National Semiconductor Corporation, clc436 Datasheet - Page 5

• Manufacturer Part Number: clc436
• Description: 200mhz, ?15v, Low-power Voltage Feedback Op Amp
• Manufacturer: National Semiconductor Corporation

Power Dissipation
The power dissipation of an amplifier can be described
in two conditions:
The following steps can be taken to determine the
power consumption of the CLC436:
The maximum power that the package can dissipate at
a given temperature is illustrated in the Power Derating
plot in the Typical Performance Characteristics
section. The power derating curve for any package
can be derived by utilizing the following equation:
where: T
Layout Considerations
A proper printed circuit layout is essential for achieving
high frequency performance. Comlinear provides eval-
uation boards for the CLC436 (730013 - DIP, 730027-
SOIC) and suggests their use as a guide for high
frequency layout and as an aid for device testing and
characterization.
Supply bypassing is required for optimum performance.
The bypass capacitors provide a low impedance
current return path at the supply pins. They also provide
high frequency filtering on the power supply traces.
Other layout factors also play a major role in high
frequency performance. The following steps are
recommended as a basis for high frequency layout:
•
•
1. Determine the quiescent power
2. Determine the RMS power at the output stage
3. Determine the total RMS power
Quiescent Power Dissipation - P
(No Load Condition)
Total Power Dissipation - P
(with Load Condition)
P
P
P
V
JA
in
amb
Q
O
T
Figure 3: Single Supply Circuit
= P
= I
= (V
= Thermal resistance, from junction to
= Ambient temperature in °C
C
ambient, for a given package in °C/W
cc
Q
1
cc
P
(V
+ P
R
R
- V
cc
1
2
V
O
cc
175
- V
load
ee
R
) (I
C
g
)
2
JA
load
CLC436
T
-
+
amb
V
)
cc
T
R
f
Q
V
o
5
State Variable Filter
The filter shown on the front page offers both a band-
pass and a low pass output. The design equations are
shown below.
The state variable filter can be modified to obtain a
tunable band pass filter. This technique is shown in
the CLC522, Wideband Variable Gain Amplifier,
data sheet.
Transimpedance Application
The low 1.1pA/ Hz input current noise and unity gain
stability make the CLC436 useful as a photo diode pre-
amplifier. Figure 4 illustrates a transimpedance amplifier.
R
is multiplied by R
The feedback capacitor (C
for the added input capacitance of the photodiode (C
The feedback capacitance reduces peaking in the fre-
quency response. As the value of the feedback capac-
itance increases from zero, the rolloff of the response
will increase.
f
sets the transimpedance gain. The photodiode current
1. Include 6.8 F tantalum and 0.01 F ceramic
2. Place the 6.8 F capacitors within 0.75 inches
3. Place the 0.01 F capacitors within 0.1 inches
4. Remove the ground plane near the input and
5. Minimize all trace lengths to reduce series
R
Q
A
f
Figure 4: Transimpedance Amplifier
bypass capacitors on both supplies.
of the power pins.
of the power pins.
output pins to reduce parasitic capacitance.
inductances.
r
I
Representation
2
v
in
Photo Diode
Applications Circuit
2 R C
R
R
R
R
R
3
1
Q
3
1
4
1
C
, desired mid band gain
f
d
, desired resonant frequency
to determine the output voltage.
f
) is required to compensate
CLC436
+
-
R
C
f
f
V
436 Fi 5
o
http://www.national.com
= I
in
* R
f
V
o
d
).