clc427 National Semiconductor Corporation, clc427 Datasheet - Page 6

• Manufacturer Part Number: clc427
• Description: Dual Voltage Feedback Amplifier For Single Supply Operation
• Manufacturer: National Semiconductor Corporation

The maximum power that the package can dissipate at a
given temperature is illustrated in the Power Derating
curves in the Typical Performance 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 evalu-
ation boards for the CLC427 (730038 - DIP, 730036-
SOIC) and suggests their use as a guide for high
frequency layout and as an aid for device testing and
characterization.
General layout and supply bypassing play major roles in
high frequency performance. Follow the steps below as
a basis for high frequency layout:
Additional information is included in the evaluation board
literature.
Typical Application Circuit
The typical application shown on the front page illustrates
the near rail-to-rail performance of the CLC427.
Multiple Feedback Bandpass Filter
Figure 9 illustrates a bandpass filter and design
equations. The circuit operates from a single supply of
+5V. The voltage divider biases the non-inverting input to
2.5V. The input is AC coupled to prevent the need for
level shifting the input signal at the source. Use the
design equations to determine R
desired Q and center frequency.
This example illustrates a bandpass filter with Q = 4 and
center frequency f
filter response.
http://www.national.com
1. Include 6.8 F tantalum and 0.1 F ceramic
2. Place the 6.8 F capacitors within 0.75 inches
3. Place the 0.1 F capacitors within 0.1 inches
4. Remove the ground plane under and around
5. Minimize all trace lengths to reduce series
ambient, for a given package (°C/W)
capacitors on both supplies.
of the power pins.
of the power pins.
the part, especially near the input and output
pins to reduce parasitic capacitance.
inductances.
JA
amb
Applications Circuits
= Thermal resistance, from junction to
= Ambient temperature (°C)
c
175
= 1MHz. Figure 10 indicates the
JA
T
amb
1
and R
2
based on the
6
Distribution Amplifier
Figure 11 illustrates a distribution amplifier. The topology
utilizes the dual amplifier package. The input is
AC coupled and the non-inverting terminals of both
amplifiers are biased at 2.5V.
V
R
R
in
1
2
4Q
R
Q
f c
R
r
2
2
o
C
Figure 9: Bandpass Filter Topology
C
-10
V
40
30
20
10
Figure 11: Distribution Amplifier
Figure 10: Bandpass Response
0
in
f
A
r
R
R
resonant frequency
2Q
50
R
2
1
3(5)
3(5)
2(6)
2(6)
R
R
C
C
g
g
A mid band gain
Frequency (MHz)
CLC427
CLC427
-
+
-
+
1
+5V
5.1k
5.1k
390pF
1/2
1/2
4
8
940kHz
C
30.6dB
6.8 F
0.1 F
+
R
R
f
f
1(7)
1(7)
3(5)
2(6)
390pF
C
CLC427
-
+
+5V
R
R
1/2
o
o
8
4
3.16k
6.8 F
0.1 F
+
R
Z
Z
o
o
10
2
1(7)
R
R
V
V
o
o
V
o 1
o 2
o