CLC452AJ-QML [TI]
OP-AMP, 6000uV OFFSET-MAX, 130MHz BAND WIDTH, CDIP8, CERDIP-8;
| 型号： | CLC452AJ-QML |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | OP-AMP, 6000uV OFFSET-MAX, 130MHz BAND WIDTH, CDIP8, CERDIP-8 放大器 CD |
| 文件： | 总19页 (文件大小：589K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
March 2001
CLC452
Single Supply, Low Power, High Output, Current
Feedback Amplifier
n −78/−85dBc HD2/HD3 (1MHz)
n 25ns settling to 0.05%
The CLC452 has a new output stage that delivers high
n 400V/µs slew rate
General Description
output drive current (100mA), but consumes minimal
quiescent supply current (3.0mA) from a single 5V supply. Its
n Stable for capacitive loads up to 1000pF
±
n Single 5V to 5V supplies
current feedback architecture, fabricated in an advanced
complementary bipolar process, maintains consistent
performance over a wide range of gains and signal levels,
and has a linear-phase response up to one half of the −3dB
frequency.
n Available in Tiny SOT23-5 package
Applications
n Coaxial cable driver
n Twisted pair driver
n Transformer/Coil Driver
n High capacitive load driver
n Video line driver
n Portable/battery powered applications
n A/D driver
The CLC452 offers superior dynamic performance with a
130MHz small signal bandwidth, 400V/µs slew rate and
4.5ns rise/fall times (2VSTEP
. The combination of low
quiescent power, high output current drive, and high speed
performance make the CLC452 well suited for many battery
powered personal communication/computing systems.
The ability to drive low impedance, high capacitive loads,
makes the CLC452 ideal for single ended cable applications.
It also drives low impedance loads with minimum distortion.
The CLC452 will drive a 100Ω load with only −75/−74dBc
second/third harmonic distortion (AV = +2, VOUT = 2VPP, f
=1MHz). With a 25Ω load, and the same conditions, it
produces only −65/−77dBc second/third harmonic distortion.
It is also optimized for driving high currents into single-ended
transformers and coils.
Maximum Output Voltage vs. RL
When driving the input of high resolution A/D converters, the
CLC452 provides excellent −78/−85dBc second/third
harmonic distortion (AV = +2, VOUT = 2VPP, f =1MHz, RL
=
1kΩ) and fast settling time.
Available in SOT23-5, the CLC452 is ideal for applications
where space is critical.
Features
n 100mA output current
n 3.0mA supply current
n 130MHz bandwidth (AV = +2)
DS012790-1
Connection Diagrams
DS012790-4
Pinout
SOT23-5
DS012790-5
Pinout
DIP & SOIC
© 2001 National Semiconductor Corporation
DS012790
www.national.com
Typical Application
DS012790-2
Single Supply Cable Driver
DS012790-3
Response After 10m of Cable
Ordering Information
Package
Temperature Range
Part Number
Package Marking
NSC Drawing
Industrial
8-pin plastic DIP
8-pin plastic SOIC
5-pin SOT
−40˚C to +85˚C
−40˚C to +85˚C
−40˚C to +85˚C
CLC452AJP
CLC452AJE
CLC452AJM5
CLC452AJP
CLC452AJE
A21
N08E
M08A
MA05A
www.national.com
2
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Lead Solder Duration (+300˚C)
ESD Rating (human body model)
10 sec
500V
Operating Ratings
Supply Voltage (VCC-(VEE
)
+14V
140mA
Thermal Resistance
Output Current (see note 3)
Common Mode Input Voltage
Maximum Junction Temperature
Package
MDIP
(θJC
)
(θJA
)
VEE to VCC
+150˚C
105˚C/W
95˚C/W
155˚C/W
175˚C/W
210˚C/W
SOIC
Storage Operating Temperature
Range
SOT23
140˚C/W
−65˚C to +150˚C
+5V Electrical Characteristics
AV = +2, VS = +5V(Note 5), VCM = VEE + (VS/2), RL = 100Ω, Rf = 1kΩ, RL tied to VCM; unless specified
Symbol
Parameter
Conditions
CLC452AJ
Typ
Min/Max (Note 2)
Units
Ambient Temperature
+25˚C
+25˚C
0 to
−40 to
70˚C
85˚C
Frequency Domain Response
<
-3dB Bandwidth
VO 0.5VPP
130
95
30
0
95
80
90
77
85
75
MHz
MHz
MHz
dB
<
VO 2.0VPP
<
−0.1dB Bandwidth
Gain Peaking
VO 0.5VPP
25
20
20
<
<
<
<
200MHz, VO 0.5VPP
0.5
0.3
0.2
0.9
0.3
0.3
1.0
0.3
0.3
<
Gain Rolloff
30MHz VO 0.5VPP
0.1
0.1
dB
linear phase deviation
TIME DOMAIN RESPONSE
Rise and Fall Time
30MHz, VO = 0.5VPP
deg
2V Step
1V Step
2V Step
2V Step
4.5
25
6.0
-
6.4
-
6.8
-
ns
ns
±
Settling Time to 0.05%
Overshoot
Slew Rate
11
15
300
18
275
18
260
%
400
V/µs
DISTORTION AND NOISE RESPONSE
2nd Harmonic Distortion
2VPP, 1MHz
−75
−78
−65
−74
−85
−60
−69
−70
−58
−70
−75
−55
−67
−68
−56
−68
−73
−53
−67
−68
−56
−68
−73
−53
dBc
dBc
dBc
dBc
dBc
dBc
2VPP,1MHz RL = 1kΩ
2VPP, 5MHz
3rd Harmonic Distortion
2VPP, 1MHz
2VPP, 1MHz RL=1kΩ
2VPP, 5MHz
Equivalent Input Noise
Voltage (eni)
>
>
>
1MHz
1MHz
1MHz
2.8
7.5
3.5
10
14
3.8
11
15
3.8
11
15
nV/
Non-Inverting Current (ibn
)
pA/
pA/
Non-Inverting Current (ibi)
10.5
Static, DC Performance
Input Offset Voltage (Note 4)
Average Drift
1
8
6
4
-
6
-
6
-
mV
µV/˚C
µA
Input Bias Current
18
22
24
(non-inverting) (Note 4)
Average Drift
40
6
-
-
-
nA/˚C
µA
Input Bias Current (inverting)
(Note 4)
14
16
17
Average Drift
25
48
51
-
-
-
nA/˚C
dB
Power Supply Rejection Ratio
Common-Mode Rejection Ratio
DC
DC
45
48
43
46
43
46
dB
3
www.national.com
+5V Electrical Characteristics (Continued)
AV = +2, VS = +5V(Note 5), VCM = VEE + (VS/2), RL = 100Ω, Rf = 1kΩ, RL tied to VCM; unless specified
Symbol
Static, DC Performance
Supply Current (Note 4)
Miscellaneous Performance
Input Resistance (non-inverting)
Parameter
Conditions
Typ
Min/Max (Note 2)
Units
∞
RL
=
3.0
3.4
3.6
3.6
mA
0.39
1.5
0.28
2.3
0.25
2.3
0.25
2.3
MΩ
Input Capacitance
(non-inverting)
pF
Input Voltage Range, High
Input Voltage Range, Low
Output Voltage Range, High
Output Voltage Range, Low
Output Voltage Range, High
Output Voltage Range, Low
Output Current (Note 3)
4.2
0.8
4.0
1.0
4.1
0.9
100
70
4.1
0.9
3.9
1.1
4.0
1.0
80
4.0
1.0
3.8
1.2
4.0
1.0
65
4.0
1.0
3.8
1.2
3.9
1.1
40
V
V
RL = 100Ω
RL = 100Ω
V
V
∞
∞
RL
RL
=
=
V
V
mA
mΩ
Output Resistance, Closed Loop
DC
105
105
140
±
5V Electrical Characteristics
±
AV = +2, VCC
=
5V, RL =100Ω, Rf = 1kΩ; unless specified
Symbol
Parameter
Conditions
CLC452AJ
Typ
Min/Max(Note 2)
Units
Ambient Temperature
+25˚C
+25˚C
0 to
−40 to
85˚C
70˚C
Frequency Domain Response
<
-3dB Bandwidth
VO 1.0VPP
160
75
135
60
25
0.5
0.2
0.2
-
120
57
25
0.9
0.3
0.3
-
115
55
20
1.0
0.3
0.3
-
MHz
MHz
MHz
dB
<
VO 4.0VPP
<
−0.1dB Bandwidth
Gain Peaking
VO 1.0VPP
30
<
<
<
<
<
<
200MHz, VO 1.0VPP
0
Gain Rolloff
30MHz, VO 1.0VPP
0.1
0.1
0.05
0.08
dB
Linear Phase Deviation
Differential Gain
30MHz, VO 1.0VPP
)
deg
%
NTSC, RL = 150Ω
NTSC, RL = 150Ω
Differential Phase
-
-
-
deg
TIME DOMAIN RESPONSE
Rise and Fall Time
2V Step
2V Step
2V Step
2V Step
3.2
20
8
4.2
-
4.5
-
5.0
-
ns
ns
±
Settling Time to 0.05%
Overshoot
Slew Rate
12
400
15
370
15
350
%
540
V/µs
DISTORTION AND NOISE RESPONSE
2nd Harmonic Distortion
2VPP,1MHz
−77
−78
−69
−72
−90
−58
−71
−72
−63
−68
−80
−54
−69
−70
−61
−66
−78
−52
−69
−70
−61
−66
−78
−52
dBc
dBc
dBc
dBc
dBc
dBc
2VPP,1MHz, RL = 1kΩ
2VPP,5MHz
3rd Harmonic Distortion
2VPP, 1MHz
2VPP, 1MHz, RL = 1kΩ
2VPP, 5MHz
Equivalent Input Noise
Voltage (eni)
>
>
>
1MHz
1MHz
1MHz
2.8
7.5
3.5
10
14
3.8
11
15
3.8
11
15
nV/
Non-Inverting current (ibn
Inverting Current (ibi)
)
pA/
pA/
10.5
www.national.com
4
±
5V Electrical Characteristics (Continued)
±
AV = +2, VCC
=
5V, RL =100Ω, Rf = 1kΩ; unless specified
Symbol
Parameter Conditions
Typ
Min/Max(Note 2)
Units
Static, DC Performance
Input Offset Voltage
1
10
3
6
-
8
-
8
-
mV
µV/˚C
µA
Average Drift
Input Bias Current
(non-inverting)
18
23
25
Average Drift
40
13
30
48
53
3.2
-
-
-
nA/˚C
µA
Input Bias Current (inverting)
Average Drift
24
-
31
-
31
-
nA/˚C
dB
Power Supply Rejection Ratio
Common-Mode Rejection Ratio
Supply Current
DC
DC
RL
45
50
3.8
43
48
4.0
43
48
4.0
dB
∞
=
mA
Miscellaneous Performance
Input Resistance (non-inverting)
0.52
1.2
0.35
1.8
0.30
1.8
0.30
1.8
MΩ
Input Capacitance
(non-inverting)
pF
±
±
±
±
±
±
±
±
±
±
±
±
Common-Mode Input Range
Output Voltage Range
4.2
3.8
4.0
4.1
3.6
3.8
4.1
3.6
3.8
4.0
3.5
3.7
V
V
RL = 100Ω
∞
Output Voltage Range
RL
=
V
Output Current (Note 3)
Output Resistance, Closed Loop
130
60
100
90
80
90
50
mA
mΩ
DC
120
Note 1: “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. They are not meant to imply that the devices
should be operated at these limits. The table of “Electrical Characteristics” specifies conditions of device operation.
Note 2: Min/max ratings are based on product characterization and simulation. Individual parameters are tested as noted. Outgoing quality levels are determined
from tested parameters.
Note 3: The short circuit current can exceed the maximum safe output current.
Note 4: AJ-level: spec. is 100% tested at +25˚C.
Note 5: V = V
− V
EE
S
CC
+5V Typical Performance Characteristics
Non-Inverting Frequency Response
Inverting Frequency Response
DS012790-6
DS012790-7
5
www.national.com
+5V Typical Performance Characteristics (Continued)
Frequency Response vs. RL
Frequency Response vs. VO
DS012790-8
DS012790-9
Frequency Response vs. CL
Open Loop Transimpedance Gain, Z(s)
DS012790-10
DS012790-11
Gain Flatness
Equivalent Input Noise
10
20
30
Frequency (MHz)
DS012790-12
DS012790-13
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6
+5V Typical Performance Characteristics (Continued)
2nd & 3rd Harmonic Distortion
2nd Harmonic Distortion, RL = 25Ω
-44
-46
-48
-50
-52
-54
-56
-58
-60
10MHz
5MHz
2MHz
1MHz
0
0.5
1
1.5
2
2.5
Output Amplitude (Vpp
)
DS012790-15
DS012790-14
3rd Harmonic Distortion, RL = 25Ω
2nd Harmonic Distortion, RL = 100Ω
-35
-40
-45
-50
-55
-60
-65
-70
-75
10MHz
5MHz
2MHz
1MHz
0
0.5
1
1.5
2
2.5
Output Amplitude (Vpp
)
DS012790-16
DS012790-17
3rd Harmonic Distortion, RL = 100Ω
2nd Harmonic Distortion, RL = 1kΩ
-45
-50
10MHz
-55
-60
-65
-70
-75
-80
5MHz
2MHz
1MHz
0
0.5
1
1.5
2
2.5
Output Amplitude (Vpp
)
DS012790-18
DS012790-19
7
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+5V Typical Performance Characteristics (Continued)
3rd Harmonic Distortion, RL = 1kΩ
Recommended RS vs. CL
PSRR & CMRR
Closed Loop Output Resistance
DS012790-20
DS012790-21
Large & Small Signal Pulse Response
DS012790-23
DS012790-22
IBN, VOS vs. Temperature
-0.6
6
5
4
3
2
1
-0.7
IBN
Vos
-0.8
-0.9
-1
-1.1
-100
-50
0
50
100
150
Temperature (ϒC)
DS012790-25
DS012790-24
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8
+5V Typical Performance Characteristics (Continued)
Maximum Output Voltage vs. RL
DS012790-26
±
5V Typical Performance Characteristics
Non-Inverting Frequency Response
Inverting Frequency Response
DS012790-27
DS012790-28
Frequency Response vs. RL
Frequency Response vs. VO
DS012790-29
DS012790-30
9
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±
5V Typical Performance Characteristics (Continued)
Frequency Response vs. CL
Gain Flatness
0
5
10
15
20
25
30
Frequency (MHz)
DS012790-32
DS012790-31
Small Signal Pulse Response
Large Signal Pulse Response
DS012790-33
DS012790-34
2nd & 3rd Harmonic Distortion
2nd Harmonic Distortion, RL = 25Ω
-40
-45
-50
-55
-60
-65
10MHz
5MHz
2MHz
1MHz
0
1
2
3
4
5
Output Amplitude (Vpp
)
DS012790-36
DS012790-35
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10
±
5V Typical Performance Characteristics (Continued)
3rd Harmonic Distortion, RL = 25Ω
2nd Harmonic Distortion, RL = 100Ω
2nd Harmonic Distortion, RL = 1kΩ
Recommended RS vs. CL
-30
-40
-50
-60
-70
-80
-90
10MHz
5MHz
1MHz
2MHz
0
1
2
3
4
5
Output Amplitude (Vpp
)
DS012790-37
DS012790-38
3rd Harmonic Distortion, RL = 100Ω
-50
-55
-60
-65
-70
-75
-80
10MHz
5MHz
2MHz
1MHz
0
1
2
3
4
5
Output Amplitude (Vpp
)
DS012790-39
DS012790-40
3rd Harmonic Distortion, RL = 1kΩ
DS012790-41
DS012790-42
11
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±
5V Typical Performance Characteristics (Continued)
Maximum Output Voltage vs. RL
Differential Gain & Phase
DS012790-44
DS012790-43
IBN, VOS vs. Temperature
Short Term Settling Time
1.5
12
8
1
0.5
4
IBN
Vos
0
0
-0.5
-4
-100
-50
0
50
100
150
Temperature (ϒC)
DS012790-45
DS012790-46
Long Term Settling Time
DS012790-47
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12
The denominator of Equation 1 is approximately equal to 1 at
low frequencies. Near the −3dB corner frequency, the
interaction between Rf and Z(jω) dominates the circuit
performance. The value of the feedback resistor has a large
affect on the circuits performance. Increasing Rf has the
following affects:
Application Division
CLC452 Operation
The CLC452 is a current feedback amplifier built in an
advanced complementary bipolar process. The CLC452
±
operates from a single 5V supply or dual 5V supplies.
Operating from single supply, the CLC452 has the
following features:
a
•
•
•
•
•
Decreases loop gain
Decreases loop bandwidth
Reduces gain peaking
•
Provides 100mA of output current while consuming
15mW of power
Lowers pulse response overshoot
Affects frequency response phase linearity
•
•
Offers low −78/−85dB 2nd and 3rd harmonic distortion
>
<
Provides BW 80MHz and 1MHz distortion −70dBc at
VO=2.0VPP
Refer to the Feedback Resistor Selection section for more
details on selecting a feedback resistor value.
±
The CLC452 performance is further enhanced in 5V supply
Design Information
±
application as indicated in the 5V Electrical Characteris-
±
tics table and 5V Typical Performance plots.
Single Supply Operation (VCC=+5V, VEE = GND)
Current Feedback Amplifiers
The specifications given in the +5V Electrical Characteris-
tics table for single supply operation are measured with a
common mode voltage (VCM) of 2.5V. VCM is the voltage
around which the inputs are applied and the output voltage
are specified.
Some of the key features of current feedback technology
are:
•
•
•
•
•
Interdependence of AC bandwidth and voltage gain
Inherently stable at unity gain
Adjustable frequency response with feedback resistor
High slew rate
Operating a single +5V supply, The Common Mode Input
Range (CMIR) of the CLC452 is typically +0.8V to +4.2V.
The typical output range with RL =100Ω is +1.0V to +4.0V.
Fast settling
Current feedback operation can be described using a simple
equation. The voltage gain for a non-inverting or inverting
current feedback amplifier is approximated by Equation 1.
Vo
Av
Rf
=
V
in
1+
Z(jω)
where:
•
•
•
•
AV is the closed loop DC voltage gain
Rf is the feedback resistor
Z(jω) is the CLC450’s open loop transimpedance gain
is the loop gain
DS012790-50
FIGURE 1. Non-Inverting Configuration
For single supply DC coupled operation, keep input signal
levels above 0.8V DC. For input signals that drop below 0.8V
DC, AC coupling and level shifting the signal are
recommended. The non-inverting and inverting configura-
tions for both input conditions are illustrated in the following
2 sections.
DC Coupled Single Supply Operation
Figure 1 and Figure 2 show the recommended non-inverting
and inverting configurations for input signals that remain
above 0.8V DC.
13
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Application Division (Continued)
DS012790-53
DS012790-51
FIGURE 4. AC Coupled Inverting Configuration
FIGURE 2. Inverting Configuration
AC Coupled Single Supply Operation
Dual Supply Operation
Figure 3 and Figure 4 show possible non-inverting and
inverting configurations for input signals that go below 0.8V
DC. The input is AC coupled to prevent the need for level
shifting the input signal at the source. The resistive voltage
divider biases the non-inverting input to VCC ÷ 2 = 2.5V (For
VCC = +5V).
The CLC452 operates on dual supplies as well as single
supplies. The non-inverting and inverting configurations are
shown in Figure 5 and Figure 6.
DS012790-54
FIGURE 5. Dual Supply Non-Inverting Configuration
DS012790-52
FIGURE 3. AC Coupled Non-Inverting Configuration
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14
resistor at the input or output of the amplifier. Figure 7 shows
typical inverting and non-inverting circuit configurations for
matching transmission lines.
Application Division (Continued)
DS012790-56
FIGURE 7. Transmission Line Matching
Non-inverting gain application:
•
•
•
Connect Rg directly to ground.
Make R1,R2, R6, R7 equal to Zo.
Use R3 to isolate the amplifier from reactive loading
caused by the transmission line, or by parasitics.
DS012790-55
Inverting gain application:
FIGURE 6. Dual Supply Inverting Configuration
•
•
•
Connect R3 directly to ground.
Make the resistors R4, R6, and R7 equal to Zo
Make R5\ Rg =Zo
Feedback Resistor Selection
The feedback resistor, Rf, affects the loop gain and
frequency response of
a current feedback amplifier.
The input and output matching resistors attenuate the signal
by a factor of 2, therefore additional gain is needed. Use C6
to match the output transmission line over
frequency range. C6 compensates for the increase of the
amplifier’s output impedance with frequency.
Optimum performance of the CLC452, at a gain of +2V/V, is
achieved with Rf equal to 1kΩ. The frequency response plots
in the Typical Performance sections illustrate the
recommended Rf provide the maximum bandwidth with
minimal peaking. Within limits, Rf can be adjusted to
optimize the frequency response.
a greater
Power Dissipation
Follow these steps to determine the power consumption of
the CLC452:
•
Decrease Rf to peak frequency response and extend
bandwidth
1. Calculate the quiescent (no-load) power:
•
Increases Rf to roll off frequency response and compress
bandwidth
Pamp = ICC (VCC − VEE
)
2. Calculate the RMS power at the output stage:
As a rule of thumb, if the recommended Rf is doubled, then
the bandwidth will be cut in half.
Po =(VCC − Vload)(Iload), where Vload and Iload are the
RMS voltage and current across the external load.
Unity Gain Operation
3. Calculate the total RMS power: Pt = Pamp + Po
The recommended Rf for unity gain (+1V/V) operation is
1kΩ. Rg is left open. Parasitic capacitance at the inverting
node may require a slight increase in Rf to maintain a flat
frequency response.
The maximum power that the DIP, SOIC, and SOT packages
can dissipate at a given temperature is illustrated in Figure 8.
The power derating cure for any CLC452 package can be
derived by utilizing the following equation:
Bandwidth vs. Output Amplitude
The bandwidth of the CLC452 is at a maximum for output
voltages near 1Vpp. The bandwidth decreases for smaller
and larger output amplitudes. Refer to the Frequency
Response vs. Vo plots.
Where
Load Termination
•
Tamb = Ambient temperature (˚C)
The CLC452 can source and sink near equal amounts of
current. For optimum performance, the load should be tied to
Vcm
.
Driving Cables and Capacitive Loads
When driving cables, double termination is used to prevent
reflections. For capacitive load application, a small series
resistor at the output of the CLC452 will improve stability and
settling performance. The Frequency Response vs. CL and
Recommended Rsvs. CL plots, in the typical performance
section, give the recommended series resistance value for
optimum flatness at various capacitive loads.
Transmission Line Matching
One method for matching the characteristic impedance (Zo)
of a transmission line or cable is to place the appropriate
15
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Components Needed to Evaluate the CLC452 on the
Evaluation Board:
Application Division (Continued)
•
θJA = Thermal resistance, from junction to ambient, for a
given package (˚C/W)
•
•
Rf, Rg — Use this product data sheet to select values.
Rin, Rout - Typically 50Ω (Refer to the Basic Operation
section of the evaluation board data sheet for details)
•
Rf — Optional resistor for inverting gain configurations
(Select Rf to yield desired input impedance = Rg\Rf
•
•
C1, C2-0.1µF ceramic capacitors
C3, C4-6.8µF tantalum capacitors
Components not used:
•
•
C5, C6, C7, C8
R1 thru R8
The evaluation boards are designed to accommodate dual
supplies. The boards can be modified to provide single
supply operation. For best performance; 1) do not connect
the unused supply, 2) ground the unused supply pin.
SPICE Models
DS012790-58
SPICE models provide a means to evaluate amplifier
designs. Free SPICE modes are available for National’s
monolithic amplifiers that:
FIGURE 8. Power Derating Curves
Layout Considerations
•
•
Support Berkeley SPICE 2G and its many derivatives
A proper printed circuit layout is essential for achieving high
frequency performance. National provides evaluation boards
for the CLC452 (730013-DIP, 730027-SOIC, 730068-SOT)
and suggests their use as a guide for high frequency layout
and as an aid for device testing and characterization.
Reproduce typical DC, AC, Transient, and Noise
performance
•
Support room temperature simulations
The readme file that accompanies the diskette lists released
models, and provides a list of modeled parameters. The
application note OA-18, Simulation SPICE Models for
National’s Op Amps, contains schematics and
reproduction of the readme file.
General layout and supply bypassing play major roles in high
frequency layout and as an aid for device testing and
characterization.
a
General layout and supply bypassing play major roles in high
frequency performance. Follow The steps below as a bias
for high frequency layout:
Application Circuits
Single Supply Cable Driver
The typical application shown on the front page shows the
CLC452 driving 10m of 75Ω coaxial cable. The CLC452 is
set for a gain of +2V/V to compensate for the divide-by-two
voltage drop at Vo.
•
•
•
•
Include 6.8µF tantalum and 0.1µF ceramic capacitors on
both supplies
Place the 6.8µF capacitors within 0.75 inches of the
power pins.
Single Supply Lowpass Filter
Place the 0.1µF capacitors less than 0.1 inches from the
power pins
Figure 9 and Figure 10 illustrate a lowpass filter and design
equation. The circuit operates from a single supply of +5V.
The voltage divider biases the non-inverting input to 2.5V.
And the input is AC coupled to prevent the need for level
shifting the input signal at the source. Use the design
equations to determine R1, R2, C1 and C2 based on the
desired Q and corner frequency.
Remove the ground plane under and around the part,
especially near the input and output pins to reduce
parasitic capacitance.
•
•
Minimize all trace lengths to reduce series inductances.
Use flush-mount printed circuit board pins for prototyping,
never use high profile DIP sockets.
•
Evaluation Board Information
Data sheet are available for the CLC730013/CLC730027
and CLC730068 evaluation boards. The velitation board
data sheets provide:
•
•
•
Evaluation board schematics
Evaluation board layouts
General information about the boards
The CLC730013/CLC730027 data sheet also contains
tables of recommended components to evaluate several of
National’s high speed amplifiers. This table for the CLC452
is illustrated below. Refer to the evaluation board data sheet
for schematics and further information.
DS012790-59
FIGURE 9. Lowpass Filter Topology
www.national.com
16
Application Division (Continued)
DS012790-61
FIGURE 11. Lowpass Response
Twisted Pair Driver
The high output current and low distortion, of the CLC452,
make it well suited for driving transformers. Figure 12
illustrates a typical twisted pair driver utilizing the CLC452
and a transformer. The transformer provides the signal and
its inversion for the twisted pair.
DS012790-60
FIGURE 10. Design Equations
This example illustrates a lowpass filter with Q = 0.707 and
corner frequency fc = 10MHz. AQ of 0.707 was chosen to
achieve a maximally flat, Butterworth response. Figure 11
indicates the filter response.
DS012790-62
FIGURE 12. Twisted Pair Driver
To match the line’s characteristic impedance (Zo) set:
•
•
RL = ZO
Rm = Req
Where Req is the transformed value of the load impedance,
(RL), and is approximated by:
Req = RL/n2
Select the transformer so that it loads the line with a value
close to Zo, over the desired frequency range. The output
impedance, Ro, of the CLC452 varies within frequency and
can also affect the return loss. The return loss, shown below,
takes into account an ideal transformer and the value of Ro
The load current (Ii) and voltage (VO) are related to the
CLC452’s maximum output voltage and current by:
From the above current relationship, it is obvious that an
amplifier with high output drive capability is required.
17
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Physical Dimensions inches (millimeters) unless otherwise noted
8-Pin SOIC
NS Package Number M08A
5-Pin SOT23
NS Package Number MA05A
www.national.com
18
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
8-Pin MDIP
NS Package Number N08E
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NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
National Semiconductor
Corporation
Americas
Tel: 1-800-272-9959
Fax: 1-800-737-7018
Email: support@nsc.com
National Semiconductor
Europe
National Semiconductor
Asia Pacific Customer
Response Group
Tel: 65-2544466
Fax: 65-2504466
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Japan Ltd.
Tel: 81-3-5639-7560
Fax: 81-3-5639-7507
Fax: +49 (0) 180-530 85 86
Email: europe.support@nsc.com
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English Tel: +44 (0) 870 24 0 2171
Français Tel: +33 (0) 1 41 91 8790
Email: ap.support@nsc.com
www.national.com
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
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