Page 1
LM7171
Very High Speed, High Output Current, Voltage
Feedback Amplifier
General Description
The LM7171 is a high speed voltage feedback amplifier that
has the slewing characteristic of a current feedback amplifier; yet it can be used inalltraditionalvoltage feedback amplifier configurations. The LM7171 is stable for gains as low
as +2 or −1. It provides a very high slew rate at 4100V/µs
and a wide unity-gain bandwidth of 200 MHz while consuming only 6.5 mA of supply current. It is ideal for video and
high speed signal processing applications such as HDSL
and pulse amplifiers. With 100 mA output current, the
LM7171 can be used for video distribution, as a transformer
driver or as a laser diode driver.
Operation on
±
15V power supplies allows for large signal
swings and provides greater dynamic range and
signal-to-noise ratio. The LM7171 offers low SFDR and
THD, ideal for ADC/DAC systems. In addition, the LM7171 is
specified for
±
5V operation for portable applications.
The LM7171 is built on National’s advanced VIP
™
III (Verti-
cally integrated PNP) complementary bipolar process.
Features
(Typical Unless Otherwise Noted)
n Easy-To-Use Voltage Feedback Topology
n Very High Slew Rate: 4100V/µs
n Wide Unity-Gain Bandwidth: 200 MHz
n −3 dB Frequency
@
A
V
=
+2: 220 MHz
n Low Supply Current: 6.5 mA
n High Open Loop Gain: 85 dB
n High Output Current: 100 mA
n Differential Gain and Phase: 0.01%, 0.02˚
n Specified for
±
15V and±5V Operation
Applications
n HDSL and ADSL Drivers
n Multimedia Broadcast Systems
n Professional Video Cameras
n Video Amplifiers
n Copiers/Scanners/Fax
n HDTV Amplifiers
n Pulse Amplifiers and Peak Detectors
n CATV/Fiber Optics Signal Processing
Typical Performance Connection Diagrams
VIP™is a trademark of National Semiconductor Corporation.
Large Signal Pulse Response
A
V
=
+2, V
S
=
±
15V
DS012385-1
8-Pin DIP/SO
DS012385-2
Top View
16-Pin Wide Body SO
DS012385-3
Top View
May 1999
LM7171 Very High Speed, High Output Current, Voltage Feedback Amplifier
© 1999 National Semiconductor Corporation DS012385 www.national.com
Page 2
Ordering Information
Package Temperature Range Transport
Media
NSC
Drawing
Industrial Military
−40˚C to +85˚C −55˚C to +125˚C
8-Pin DIP LM7171AIN, LM7171BIN Rails N08E
8-Pin CDIP LM7171AMJ-QML
LM7171AMJ-QMLV
5962-95536 Rails J08A
10-Pin Ceramic
SOIC
LM7171AMWG-QML
LM7171AMWG-QMLV
5962-95536 Trays WG10A
8-Pin LM7171AIM, LM7171BIM Rails M08A
Small Outline LM7171AIMX, LM7171BIMX Tape and Reel
16-Pin LM7171AIWM, LM7171BIWM Rails M16B
Small Outline LM7171AWMX, LM7171BWMX Tape and Reel
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Page 3
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
ESD Tolerance (Note 2) 2.5 kV
Supply Voltage (V
+–V−
) 36V
Differential Input Voltage (Note 11)
±
10V
Output Short Circuit to Ground
(Note 3) Continuous
Storage Temperature Range −65˚C to +150˚C
Maximum Junction Temperature
(Note 4) 150˚C
Operating Ratings (Note 1)
Supply Voltage 5.5V ≤ V
S
≤ 36V
Junction Temperature Range
LM7171AI, LM7171BI −40˚C ≤ T
J
≤ +85˚C
Thermal Resistance (θ
JA
)
N Package, 8-Pin Molded DIP 108˚C/W
M Package, 8-Pin Surface Mount 172˚C/W
M Package, 16-Pin Surface Mount 95˚C/W
±
15V DC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for T
J
=
25˚C, V
+
=
+15V, V
−
=
−15V, V
CM
=
0V, and R
L
=
1kΩ.Boldface
limits apply at the temperature extremes
Symbol Parameter Conditions Typ
(Note 5)
LM7171AI LM7171BI Units
Limit Limit
(Note 6) (Note 6)
V
OS
Input Offset Voltage 0.2 1 3 mV
47max
TC V
OS
Input Offset Voltage 35 µV/˚C
Average Drift
I
B
Input Bias Current 2.7 10 10 µA
12 12 max
I
OS
Input Offset Current 0.1 4 4 µA
66max
R
IN
Input Resistance Common Mode 40 MΩ
Differential Mode 3.3
R
O
Open Loop Output 15 Ω
Resistance
CMRR Common Mode V
CM
=
±
10V 105 85 75 dB
Rejection Ratio 80 70 min
PSRR Power Supply V
S
=
±
15V to±5V 90 85 75 dB
Rejection Ratio 80 70 min
V
CM
Input Common-Mode CMRR>60 dB
±
13.35 V
Voltage Range
A
V
Large Signal Voltage R
L
=
1kΩ 85 80 75 dB
Gain (Note 7) 75 70 min
R
L
=
100Ω 81 75 70 dB
70 66 min
V
O
Output Swing R
L
=
1kΩ 13.3 13 13 V
12.7 12.7 min
−13.2 −13 −13 V
−12.7 −12.7 max
R
L
=
100Ω 11.8 10.5 10.5 V
9.5 9.5 min
−10.5 −9.5 −9.5 V
−9 −9 max
Output Current Sourcing, R
L
=
100Ω 118 105 105 mA
(Open Loop) 95 95 min
(Note 8) Sinking, R
L
=
100Ω 105 95 95 mA
90 90 max
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Page 4
±
15V DC Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for T
J
=
25˚C, V
+
=
+15V, V
−
=
−15V, V
CM
=
0V, and R
L
=
1kΩ.Boldface
limits apply at the temperature extremes
Symbol Parameter Conditions Typ
(Note 5)
LM7171AI LM7171BI Units
Limit Limit
(Note 6) (Note 6)
Output Current Sourcing, R
L
=
100Ω 100 mA
(in Linear Region) Sinking, R
L
=
100Ω 100
I
SC
Output Short Circuit Sourcing 140 mA
Current Sinking 135
I
S
Supply Current 6.5 8.5 8.5 mA
9.5 9.5 max
±
15V AC Electrical Characteristics
Unless otherwise specified, T
J
=
25˚C, V
+
=
+15V, V
−
=
−15V, V
CM
=
0V, and R
L
=
1kΩ.
Typ LM7171AI LM7171BI
Symbol Parameter Conditions (Note 5) Limit Limit Units
(Note 6) (Note 6)
SR Slew Rate (Note 9) A
V
=
+2, V
IN
=
13 V
PP
4100 V/µs
A
V
=
+2, V
IN
=
10 V
PP
3100
Unity-Gain Bandwidth 200 MHz
−3 dB Frequency A
V
=
+2 220 MHz
φ
m
Phase Margin 50 Deg
t
s
Settling Time (0.1%)A
V
=
−1, V
O
=
±
5V 42 ns
R
L
=
500Ω
t
p
Propagation Delay A
V
=
−2, V
IN
=
±
5V, 5 ns
R
L
=
500Ω
A
D
Differential Gain (Note 10) 0.01
%
φ
D
Differential Phase (Note 10) 0.02 Deg
Second Harmonic (Note 12) f
IN
=
10 kHz −110 dBc
f
IN
=
5 MHz −75 dBc
Third Harmonic (Note 12) f
IN
=
10 kHz −115 dBc
f
IN
=
5 MHz −55 dBc
e
n
Input-Referred f=10 kHz
14
Voltage Noise
i
n
Input-Referred f=10 kHz
1.5
Current Noise
±
5V DC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for T
J
=
25˚C, V
+
=
+5V, V
−
=
−5V, V
CM
=
0V, and R
L
=
1kΩ.Boldface lim-
its apply at the temperature extremes
Typ LM7171AI LM7171BI
Symbol Parameter Conditions (Note 5) Limit Limit Units
(Note 6) (Note 6)
V
OS
Input Offset Voltage 0.3 1.5 3.5 mV
47max
TC V
OS
Input Offset Voltage 35 µV/˚C
Average Drift
I
B
Input Bias Current 3.3 10 10 µA
12 12 max
I
OS
Input Offset Current 0.1 4 4 µA
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Page 5
±
5V DC Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for T
J
=
25˚C, V
+
=
+5V, V
−
=
−5V, V
CM
=
0V, and R
L
=
1kΩ.Boldface lim-
its apply at the temperature extremes
Typ LM7171AI LM7171BI
Symbol Parameter Conditions (Note 5) Limit Limit Units
(Note 6) (Note 6)
66max
R
IN
Input Resistance Common Mode 40 MΩ
Differential Mode 3.3
R
O
Output Resistance 15 Ω
CMRR Common Mode V
CM
=
±
2.5V 104 80 70 dB
Rejection Ratio 75 65 min
PSRR Power Supply V
S
=
±
15V to±5V 90 85 75 dB
Rejection Ratio 80 70 min
V
CM
Input Common-Mode CMRR>60 dB
±
3.2 V
Voltage Range
A
V
Large Signal Voltage R
L
=
1kΩ 78 75 70 dB
Gain (Note 7) 70 65 min
R
L
=
100Ω 76 72 68 dB
67 63 min
V
O
Output Swing R
L
=
1kΩ 3.4 3.2 3.2 V
33min
−3.4 −3.2 −3.2 V
−3 −3 max
R
L
=
100Ω 3.1 2.9 2.9 V
2.8 2.8 min
−3.0 −2.9 −2.9 V
−2.8 −2.8 max
Output Current Sourcing, R
L
=
100Ω 31 29 29 mA
(Open Loop) (Note 8) 28 28 min
Sinking, R
L
=
100Ω 30 29 29 mA
28 28 max
I
SC
Output Short Circuit Sourcing 135 mA
Current Sinking 100
I
S
Supply Current 6.2 8 8 mA
99max
±
5V AC Electrical Characteristics
Unless otherwise specified, T
J
=
25˚C, V
+
=
+5V, V
−
=
−5V, V
CM
=
0V, and R
L
=
1kΩ.
Typ LM7171AI LM7171BI
Symbol Parameter Conditions (Note 5) Limit Limit Units
(Note 6) (Note 6)
SR Slew Rate (Note 9) A
V
=
+2, V
IN
=
3.5 V
PP
950 V/µs
Unity-Gain Bandwidth 125 MHz
−3 dB Frequency A
V
=
+2 140 MHz
φ
m
Phase Margin 57 Deg
t
s
Settling Time (0.1%)A
V
=
−1, V
O
=
±
1V, 56 ns
R
L
=
500Ω
t
p
Propagation Delay A
V
=
−2, V
IN
=
±
1V, 6 ns
R
L
=
500Ω
A
D
Differential Gain (Note 1) 0.02
%
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Page 6
±
5V AC Electrical Characteristics (Continued)
Unless otherwise specified, T
J
=
25˚C, V
+
=
+5V, V
−
=
−5V, V
CM
=
0V, and R
L
=
1kΩ.
Typ LM7171AI LM7171BI
Symbol Parameter Conditions (Note 5) Limit Limit Units
(Note 6) (Note 6)
φ
D
Differential Phase (Note 10) 0.03 Deg
Second Harmonic (Note 12) f
IN
=
10 kHz −102 dBc
f
IN
=
5 MHz −70 dBc
Third Harmonic (Note 12) f
IN
=
10 kHz −110 dBc
f
IN
=
5 MHz −51 dBc
e
n
Input-Referred f=10 kHz 14
Voltage Noise
i
n
Input-Referred f=10 kHz
1.8
Current Noise
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics.
Note 2: Human body model, 1.5 kΩ in series with 100 pF.
Note 3: Applies to both single-supply and split-supply operation. Continuous short circuit operation at elevated ambient temperature can result in exceeding the
maximum allowed junction temperature of 150˚C.
Note 4: The maximum power dissipation is a function of T
J(max)
, θJA, and TA. The maximum allowable power dissipation at any ambient temperature is P
D
=
(T
J(max)–TA
)/θJA. All numbers apply for packages soldered directly into a PC board.
Note 5: Typifcal values represent the most likely parametric norm.
Note 6: All limits are guaranteed by testing or statistical analysis.
Note 7: Large signal voltage gain is the total output swing divided by the input signal required to produce that swing. For V
S
=
±
15V, V
OUT
=
±
5V. For V
S
=
±
5V,
V
OUT
=
±
1V.
Note 8: The open loop output current is guaranteed, by the measurement of the open loop output voltage swing, using 100Ω output load.
Note 9: Slew Rate is the average of the raising and falling slew rates.
Note 10: Differential gain and phase are measured with A
V
=
+2, V
IN
=
1V
PP
at 3.58 MHz and both input and output 75Ω terminated.
Note 11: Input differential voltage is applied at V
S
=
±
15V.
Note 12: Harmonics are measured with V
IN
=
1V
PP,AV
=
+2 and R
L
=
100Ω.
Typical Performance Characteristics unless otherwise noted, T
A
= 25˚C
Supply Current
vs Supply Voltage
DS012385-63
Supply Current
vs Temperature
DS012385-64
Input Offset Voltage
vs Temperature
DS012385-65
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Page 7
Typical Performance Characteristics unless otherwise noted, T
A
= 25˚C (Continued)
Input Bias Current
vs Temperature
DS012385-66
Short Circuit Current
vs Temperature (Sourcing)
DS012385-67
Short Circuit Current
vs Temperature (Sinking)
DS012385-68
Output Voltage
vs Output Current
DS012385-69
Output Voltage
vs Output Current
DS012385-70
CMRR vs Frequency
DS012385-71
PSRR vs Frequency
DS012385-72
PSRR vs Frequency
DS012385-73
Open Loop Frequency
Response
DS012385-51
Open Loop Frequency
Response
DS012385-52
Gain-Bandwidth Product
vs Supply Voltage
DS012385-53
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Page 8
Typical Performance Characteristics unless otherwise noted, T
A
= 25˚C (Continued)
Gain-Bandwidth Product
vs Load Capacitance
DS012385-54
Large Signal Voltage Gain
vs Load
DS012385-55
Large Signal Voltage Gain
vs Load
DS012385-56
Input Voltage Noise
vs Frequency
DS012385-57
Input Voltage Noise
vs Frequency
DS012385-58
Input Current Noise
vs Frequency
DS012385-59
Input Current Noise
vs Frequency
DS012385-60
Slew Rate
vs Supply Voltage
DS012385-61
Slew Rate
vs Input Voltage
DS012385-62
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Page 9
Typical Performance Characteristics unless otherwise noted, T
A
= 25˚C (Continued)
Slew Rate
vs Load Capacitance
DS012385-23
Open Loop Output
Impedance vs Frequency
DS012385-25
Open Loop Output
Impedance vs Frequency
DS012385-26
Large Signal Pulse
Response A
V
=
−1,
V
S
=
±
15V
DS012385-27
Large Signal Pulse
Response A
V
=
−1,
V
S
=
±
5V
DS012385-28
Large Signal Pulse
Response A
V
=
+2,
V
S
=
±
15V
DS012385-29
Large Signal Pulse
Response A
V
=
+2,
V
S
=
±
5V
DS012385-30
Small Signal Pulse
Response A
V
=
−1,
V
S
=
±
15V
DS012385-31
Small Signal Pulse
Response A
V
=
−1,
V
S
=
±
5V
DS012385-32
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Page 10
Typical Performance Characteristics unless otherwise noted, T
A
= 25˚C (Continued)
Small Signal Pulse
Response A
V
=
+2,
V
S
=
±
15V
DS012385-33
Small Signal Pulse
Response A
V
=
+2,
V
S
=
±
5V
DS012385-34
Closed Loop Frequency
Response vs Supply
Voltage (A
V
=
+2)
DS012385-35
Closed Loop Frequency
Response vs Capacitive
Load (A
V
=
+2)
DS012385-36
Closed Loop Frequency
Response vs Capacitive
Load (A
V
=
+2)
DS012385-37
Closed Loop Frequency
Response vs Input Signal
Level (A
V
=
+2)
DS012385-38
Closed Loop Frequency
Response vs Input Signal
Level (A
V
=
+2)
DS012385-43
Closed Loop Frequency
Response vs Input Signal
Level (A
V
=
+2)
DS012385-39
Closed Loop Frequency
Response vs Input Signal
Level (A
V
=
+2)
DS012385-40
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Page 11
Typical Performance Characteristics unless otherwise noted, T
A
= 25˚C (Continued)
Closed Loop Frequency
Response vs Input Signal
Level (A
V
=
+4)
DS012385-44
Closed Loop Frequency
Response vs Input Signal
Level (A
V
=
+4)
DS012385-45
Closed Loop Frequency
Response vs Input Signal
Level (A
V
=
+4)
DS012385-41
Closed Loop Frequency
Response vs Input Signal
Level (A
V
=
+4)
DS012385-42
Total Harmonic Distortion
vs Frequency (Note 13)
DS012385-46
Total Harmonic Distortion
vs Frequency (Note 13)
DS012385-47
Undistorted Output Swing
vs Frequency
DS012385-49
Undistorted Output Swing
vs Frequency
DS012385-48
Undistorted Output Swing
vs Frequency
DS012385-50
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Page 12
Typical Performance Characteristics unless otherwise noted, T
A
= 25˚C (Continued)
Note 13: The THD measurement at low frequency is limited by the test instrument.
Simplified Schematic Diagram
Application Notes
LM7171 Performance Discussion
The LM7171 is a very high speed, voltage feedback amplifier. It consumes only 6.5 mA supply current while providing
a unity-gain bandwidth of 200 MHz and a slew rate of 4100V/
µs. It also has other great features such as low differential
gain and phase and high output current.
The LM7171 is a true voltage feedback amplifier. Unlike current feedback amplifiers (CFAs) with a low inverting input impedance and a high non-inverting input impedance, both inputs of voltage feedback amplifiers (VFAs) have high
impedance nodes. The low impedance inverting input in
CFAs and a feedback capacitor create an additional pole
that will lead to instability. As a result, CFAs cannot be used
in traditional op amp circuits such as photodiode amplifiers,
I-to-V converters and integrators where a feedback capacitor
is required.
LM7171 Circuit Operation
The class AB input stage in LM7171 is fully symmetrical and
has a similar slewing characteristic to the current feedback
amplifiers. In the LM7171 Simplified Schematic, Q1 through
Q4 form the equivalent of the current feedback input buffer,
R
E
the equivalent of the feedback resistor, and stage A buff-
Harmonic Distortion
vs Frequency
DS012385-74
Harmonic Distortion
vs Frequency
DS012385-75
Maximum Power Dissipation
vs Ambient Temperature
DS012385-20
DS012385-9
Note: M1 and M2 are current mirrors.
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Page 13
LM7171 Circuit Operation (Continued)
ers the inverting input. The triple-buffered output stage isolates the gain stage from the load to provide low output impedance.
LM7171 Slew Rate Characteristic
The slew rate of LM7171 is determined by the current available to charge and discharge an internal high impedance
node capacitor. This current is the differential input voltage
divided by the total degeneration resistor R
E
. Therefore, the
slew rate is proportional to the input voltage level, and the
higher slew rates are achievable in the lower gain configurations. A curve of slew rate versus input voltage level is provided in the “Typical Performance Characteristics”.
When a very fast large signal pulse is applied to the input of
an amplifier, some overshoot or undershoot occurs. By placing an external resistor such as 1 kΩ in series with the input
of LM7171, the bandwidth is reduced to help lower the overshoot.
Slew Rate Limitation
If the amplifier’s input signal has too large of an amplitude at
too high of a frequency, the amplifier is said to be slew rate
limited; this can cause ringing in time domain and peaking in
frequency domain at the output of the amplifier.
In the “Typical Performance Characteristics” section, there
are several curves of A
V
=
+2 and A
V
=
+4 versus input sig-
nal levels. For the A
V
=
+4 curves, no peaking is present and
the LM7171 responds identically to the different input signal
levels of 30 mV, 100 mV and 300 mV.
For the A
V
=
+2 curves, with slight peaking occurs. This
peaking at high frequency (
>
100 MHz) is caused by a large
input signal at high enough frequency that exceeds the amplifier’s slew rate. The peaking in frequency response does
not limit the pulse response in time domain, and the LM7171
is stable with noise gain of ≥+2.
Layout Consideration
PRINTED CIRCUIT BOARDS AND HIGH SPEED OP
AMPS
There are many things to consider when designing PC
boards for high speed op amps. Without proper caution, it is
very easy to have excessive ringing, oscillation and other degraded AC performance in high speed circuits. As a rule, the
signal traces should be short and wide to provide low inductance and low impedance paths. Any unused board space
needs to be grounded to reduce stray signal pickup. Critical
components should also be grounded at a common point to
eliminate voltage drop. Sockets add capacitance to the
board and can affect high frequency performance. It is better
to solder the amplifier directly into the PC board without using any socket.
USING PROBES
Active (FET) probes are ideal for taking high frequency measurements because they have wide bandwidth, high input
impedance and low input capacitance. However, the probe
ground leads provide a long ground loop that will produce errors in measurement. Instead, the probes can be grounded
directly by removing the ground leads and probe jackets and
using scope probe jacks.
COMPONENT SELECTION AND FEEDBACK RESISTOR
It is important in high speed applications to keep all component leads short. For discrete components, choose carbon
composition-type resistors and mica-type capacitors. Surface mount components are preferred over discrete components for minimum inductive effect.
Large values of feedback resistors can couple with parasitic
capacitance and cause undesirable effects such as ringing
or oscillation in high speed amplifiers. For LM7171, a feedback resistor of 510Ω gives optimal performance.
Compensation for Input
Capacitance
The combination of an amplifier’s input capacitance with the
gain setting resistors adds a pole that can cause peaking or
oscillation. To solve this problem, a feedback capacitor with
a value
C
F
>
(RGxCIN)/R
F
can be used to cancel that pole. For LM7171, a feedback capacitor of 2 pF is recommended.
Figure 1
illustrates the com-
pensation circuit.
Power Supply Bypassing
Bypassing the power supply is necessary to maintain low
power supply impedance across frequency. Both positive
and negative power supplies should be bypassed individually by placing 0.01 µF ceramic capacitors directly to power
supply pins and 2.2 µF tantalum capacitors close to the
power supply pins.
Termination
In high frequency applications, reflections occur if signals
are not properly terminated.
Figure 3
shows a properly termi-
nated signal while
Figure 4
shows an improperly terminated
signal.
DS012385-10
FIGURE 1. Compensating for Input Capacitance
DS012385-11
FIGURE 2. Power Supply Bypassing
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Page 14
Termination (Continued)
To minimize reflection, coaxial cable with matching characteristic impedance to the signal source should be used. The
other end of the cable should be terminated with the same
value terminator or resistor. For the commonly used cables,
RG59 has 75Ω characteristic impedance, and RG58 has
50Ω characteristic impedance.
Driving Capacitive Loads
Amplifiers driving capacitive loads can oscillate or have ringing at the output. To eliminate oscillation or reduce ringing,
an isolation resistor can be placed as shown below in
Figure
5
The combination of the isolation resistor and the load capacitor forms a pole to increase stability by adding more
phase margin to the overall system. The desired performance depends on the value of the isolation resistor; the bigger the isolation resistor, the more damped the pulse response becomes. For LM7171, a 50Ω isolation resistor is
recommended for initial evaluation.
Figure 6
shows the
LM7171 driving a 150 pF load with the 50Ω isolation resistor.
Power Dissipation
The maximum power allowed to dissipate in a device is defined as:
P
D
=
(T
J(max)−TA
)/θ
JA
Where
PD is the power dissipation in a device
T
J(max)
is the maximum junction temperature
T
A
is the ambient temperature
θ
JA
is the thermal resistance of a particular package
For example, for the LM7171 in a SO-8 package, the maximum power dissipation at 25˚C ambient temperature is
730 mW.
Thermal resistance, θ
JA
, depends on parameters such as
die size, package size and package material. The smaller
the die size and package, the higher θ
JA
becomes. The 8-pin
DIP package has a lower thermal resistance (108˚C/W) than
that of 8-pin SO (172˚C/W). Therefore, for higher dissipation
capability, use an 8-pin DIP package.
The total power dissipated in a device can be calculated as:
P
D
=
P
Q+PL
PQis the quiescent power dissipated in a device with no load
connected at the output. P
L
is the power dissipated in the device with a load connected at the output; it is not the power
dissipated by the load.
Furthermore,
P
Q
:=supply current x total supply voltage with no load
P
L
:
=
output current x (voltage difference between
supply voltage and output voltage of the same
side of supply voltage)
DS012385-17
FIGURE 3. Properly Terminated Signal
DS012385-18
FIGURE 4. Improperly Terminated Signal
DS012385-12
FIGURE 5. Isolation Resistor Used
to Drive Capacitive Load
DS012385-13
FIGURE 6. The LM7171 Driving a 150 pF Load
with a 50Ω Isolation Resistor
www.national.com 14
Page 15
Power Dissipation (Continued)
For example, the total power dissipated by the LM7171 with
V
S
=
±
15V and output voltage of 10V into 1 kΩ is
P
D
=
P
Q+PL
=
(6.5 mA) x (30V) + (10 mA) x (15V − 10V)
=
195mW+50mW
=
245 mW
Application Circuit
Fast Instrumentation Amplifier
DS012385-14
DS012385-80
Multivibrator
DS012385-15
DS012385-81
Pulse Width Modulator
DS012385-16
www.national.com15
Page 16
Application Circuit (Continued)
Video Line Driver
DS012385-21
www.national.com 16
Page 17
Design Kit
A design kit is available for the LM7171. The design kit contains:
•
High Speed Evaluation Board
•
LM7171 in 8-pin DIP Package
•
LM7171 Datasheet
•
Pspice Macromodel DIskette With The LM7171 Macromodel
•
Amplifier Selection Guide
Pitch Pack
Apitch pack is available for the LM7171. The pitch pack contains:
•
LM7171 in 8-pin DIP Package
•
LM7171 Datasheet
•
Pspice Macromodel DIskette With The LM7171 Macromodel
•
Amplifier Selection Guide
Contact your local National Semiconductor sales office to
obtain a pitch pack and design kit.
www.national.com17
Page 18
Physical Dimensions inches (millimeters) unless otherwise noted
Order Number LM7171AIM, LM7171BIM,
LM7171AIMX or LM7171BIMX
8-Lead (0.150" Wide) Molded Small Outline Package, JEDEC
NS Package Number M08A
www.national.com 18
Page 19
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
Order Number LM7171AIWM, LM7171BIWM,
LM7171AIWMX or LM7171BIWMX
16-Lead (0.300" Wide) Molded Small Outline Package, JEDEC
NS Package Number M16B
Order Number LM7171AIN or LM7171BIN
8-Lead (0.300" Wide) Molded Dual-In-Line Package, JEDEC
NS Package Number N08E
www.national.com19
Page 20
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
LIFE SUPPORT POLICY
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
Fax: +49 (0) 1 80-530 85 86
Email: europe.support@nsc.com
Deutsch Tel: +49 (0) 1 80-530 85 85
English Tel: +49 (0) 1 80-532 78 32
Français Tel: +49 (0) 1 80-532 93 58
Italiano Tel: +49 (0) 1 80-534 16 80
National Semiconductor
Asia Pacific Customer
Response Group
Tel: 65-2544466
Fax: 65-2504466
Email: sea.support@nsc.com
National Semiconductor
Japan Ltd.
Tel: 81-3-5639-7560
Fax: 81-3-5639-7507
www.national.com
Order Number 5962-9553601QPA
8-Lead Dual-In-Line Package
NS Package Number J08A
NSID is LM7171AMJ/883
LM7171 Very High Speed, High Output Current, Voltage Feedback Amplifier
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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