查询LMH6723 LMH6724 LMH6725供应商
LMH6723/LMH6724/LMH6725
Single/Dual/Quad 370 MHz 1 mA Current Feedback Op
Amp
LMH6723/LMH6724/LMH6725 Single/Dual/Quad 370 MHz 1 mA Current Feedback Op Amp
May 2004
General Description
The LMH6723/LMH6724/LMH6725 provides a 260 MHz
small signal bandwidth at a gain of +2 V/V and a 600 V/µs
slew rate while consuming only 1 mA from
The LMH6723/LMH6724/LMH6725 supports video applications with its 0.03% and 0.11˚ differential gain and phase
errors for NTSC and PAL video signals while driving a back
terminated 75Ω load. The LMH6723/LMH6724/LMH6725
also offers a flat gain response of 0.1 dB to 100 MHz.
Additionally, the LMH6723/LMH6724/LMH6725 can deliver
110 mA of linear output current. This level of performance, as
well as a wide supply range of 4.5 to 12V, makes the
LMH6723/LMH6724/LMH6725 an ideal op amp for a variety
of portable applications. The LMH6723/LMH6724/
LMH6725’s small packages (SOIC & SOT23), low power
requirement and high performance, allow the LMH6723/
LMH6724/LMH6725 to serve a wide variety of portable applications.
The LMH6723/LMH6724/LMH6725 is manufactured in National’s VIP
™
10 complimentary bipolar process.
±
5V supplies.
Typical Application
Features
n Large signal bandwidth and slew rate 100% tested
n 370 MHz bandwidth (A
BW
n 260 MHz (A
n 1 mA supply current
n 110 mA linear output current
n 0.03%, 0.11˚ differential gain, phase
n 0.1 dB gain flatness to 100 MHz
n Fast slew rate: 600 V/µs
n Unity gain stable
n Single supply range of 4.5 to 12V
n Improved replacement for CLC450, CLC452, (LMH6723)
=+2V/V,V
V
=1,V
V
OUT
= 0.5 VPP)−3dB
OUT
= 0.5 VPP)−3dBBW
Applications
n Line driver
n Portable video
n A/D driver
n Portable DVD
Single Supply Cable Driver
© 2004 National Semiconductor Corporation DS200789 www.national.com
20078936
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
Human Body Model 2000V
Machine Model (Note 4) 200V
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
(V+-V-)
V
CC
I
OUT
120 mA (Note 3)
Common Mode Input Voltage
Maximum Junction Temperature +150˚C
Storage Temperature Range −65˚C to +150˚C
Soldering Information
LMH6723/LMH6724/LMH6725
Infrared or Convection (20 sec) 235˚C
Wave Soldering (10 sec) 260˚C
±
6.75V
±
V
CC
Operating Ratings (Note 3)
Thermal Resistance
Package (θ
8-Pin SOIC 166˚C/W
5-Pin SOT23 230˚C/W
14-Pin SOIC 130˚C/W
Operating Temperature Range −40˚C to +85˚C
Nominal Supply Voltage 4.5V to 12V
ESD Tolerance (Note 4)
±
5V Electrical Characteristics
Unless specified, AV= +2, RF= 1200Ω,RL= 100Ω. Boldface limits apply at temperature extremes. (Note 2)
Symbol Parameter Conditions Min Typ Max Units
Frequency Domain Response
SSBW −3 dB Bandwidth Small Signal V
LSBW −3dB Bandwidth Large Signal V
OUT
OUT
= 0.5 V
= 4.0 V
PP
PP
LMH6723 90 110
LMH6724
85 95
260 MHz
LMH6725
UGBW −3 dB Bandwidth Unity Gain V
.1dB BW .1 dB Bandwidth V
DG Differential Gain R
DP Differential Phase R
=.2VPPAV= 1 V/V 370 MHz
OUT
= 0.5 V
OUT
= 150Ω, 4.43 MHz 0.03 %
L
= 150Ω, 4.43 MHz 0.11 deg
L
PP
100 MHz
Time Domain Response
TRS Rise and Fall Time 4V Step 2.5 ns
TSS Settling Time to 0.05% 2V Step 30 ns
SR Slew Rate 4V Step 500 600 V/µs
Distortion and Noise Response
HD2 2
HD3 3
nd
Harmonic Distortion 2 VPP, 5 MHz −65 dBc
rd
Harmonic Distortion 2 VPP, 5 MHz −63 dBc
Equivalent Input Noise
VN Non-Inverting Voltage Noise
NICN Inverting Current Noise
ICN Non-Inverting Current Noise
>
1 MHz 4.3 nV/
>
1 MHz 6 pA/
>
1 MHz 6 pA/
Static, DC Performance
V
IO
I
BN
I
BI
Input Offset Voltage 1
Input Bias Current Non-Inverting −2
Input Bias Current Inverting 0.4
PSRR Power Supply Rejection Ratio DC, 1V Step LMH6723 59
64
±
3
±
3.7
±
4
±
5
±
4
±
5
57
LMH6724 59
64
55
LMH6725 59
64
56
JA
MHz
mV
µA
µA
dB
)
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±
5V Electrical Characteristics (Continued)
Unless specified, AV= +2, RF= 1200Ω,RL= 100Ω. Boldface limits apply at temperature extremes. (Note 2)
Symbol Parameter Conditions Min Typ Max Units
CMRR Common Mode Rejection Ratio DC, 1V Step LMH6723 57
60
55
LMH6724 57
60
53
LMH6725 57
60
54
I
CC
Supply Current (per amplifier) RL=
∞
1 1.2
mA
1.4
Miscellaneous Performance
R
IN+
R
IN−
Input Resistance Non-Inverting 100 kΩ
Input Resistance
Inverting 500 Ω
(Output Resistance of Input
Buffer)
C
IN
R
OUT
V
O
V
OL
Input Capacitance Non-Inverting 1.5 pF
Output Resistance Closed Loop 0.01 Ω
Output Voltage Range RL=
∞
LMH6723
LMH6724
LMH6725
Output Voltage Range, High RL= 100Ω 3.6
±
±
±
±
3.85
4
3.9
4
±
±
4.1
4.1
3.7
3.5
Output Voltage Range, Low R
= 100Ω −3.25
L
−3.45
−3.1
CMVR Input Voltage Range Common Mode, CMRR>50 dB
I
O
Output Current Sourcing, V
Sinking, V
=0 95
OUT
= 0 −80
OUT
±
4.0 V
110
70
110
mA
−70
LMH6723/LMH6724/LMH6725
dB
V
V
±
2.5V Electrical Characteristics
Unless otherwise specified, AV= +2, RF= 1200Ω,RL= 100Ω. Boldface limits apply at temperature extremes. (Note 2)
Symbol Parameter Conditions Min Typ Max Units
Frequency Domain Response
SSBW −3 dB Bandwidth Small Signal V
LSBW −3 dB Bandwidth Large Signal V
OUT
OUT
= 0.5 V
= 2.0 V
PP
PP
LMH6723
95 125
LMH6724
210 MHz
MHz
LMH6725 90 100
UGBW −3 dB Bandwidth Unity Gain V
.1dB BW .1 dB Bandwidth V
DG Differential Gain R
DP Differential Phase R
= 0.5 VPP,AV= 1 V/V 290 MHz
OUT
= 0.5 V
OUT
= 150Ω, 4.43 MHz .03 %
L
= 150Ω, 4.43 MHz 0.1 deg
L
PP
100 MHz
Time Domain Response
TRS Rise and Fall Time 2V Step 4 ns
SR Slew Rate 2V Step 275 400 V/µs
Distortion and Noise Response
HD2 2
HD3 3
nd
Harmonic Distortion 2 VPP, 5 MHz −67 dBc
rd
Harmonic Distortion 2 VPP, 5 MHz −67 dBc
Equivalent Input Noise
VN Non-Inverting Voltage
>
1 MHz 4.3 nV/
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±
2.5V Electrical Characteristics (Continued)
Unless otherwise specified, AV= +2, RF= 1200Ω,RL= 100Ω. Boldface limits apply at temperature extremes. (Note 2)
Symbol Parameter Conditions Min Typ Max Units
NICN Inverting Current
ICN Non-Inverting Current
>
1MHz 6 pA/
>
1MHz 6 pA/
Static, DC Performance
V
IO
I
BN
Input Offset Voltage −0.5
Input Bias Current Non-Inverting −2.7
LMH6723/LMH6724/LMH6725
I
BI
PSRR Power Supply Rejection Ratio DC, 0.5V Step LMH6723 59
Input Bias Current Inverting −0.7
62
±
3
±
3.4
±
4
±
5
±
4
±
5
57
LMH6724 58
62
55
LMH6725 59
62
56
CMRR Common Mode Rejection Ratio DC, 0.5V Step LMH6723 57
59
53
LMH6724 55
59
52
LMH6725 57
59
52
I
CC
Supply Current (per amplifier) RL=
∞
.9 1.1
1.3
Miscellaneous Performance
R
IN+
R
IN−
Input Resistance Non-Inverting 100 kΩ
Input Resistance
Inverting 500 Ω
(Output Resistance of Input
Buffer)
C
IN
R
OUT
V
O
V
OL
Input Capacitance Non-Inverting 1.5 pF
Output Resistance Closed Loop .02 Ω
Output Voltage Range RL=
∞
Output Voltage Range, High RL= 100Ω LMH6723 1.35
±
1.55
±
1.4
±
1.65 V
1.45
1.27
Output Voltage Range, Low R
LMH6724
LMH6725
= 100Ω LMH6723 −1.25
L
1.35
1.26
1.45
−1.38
−1.15
CMVR Input Voltage Range Common Mode, CMRR
I
O
Output Current Sourcing 70
>
LMH6724
LMH6725
50 dB
−1.25
−1.38
−1.15
±
1.45 V
90
60
Sinking −30
−60
−30
mV
µA
µA
dB
dB
mA
V
V
mA
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, see the Electrical Characteristics tables.
Note 2: Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating of
the device such that T
See Applications Section for information on temperature derating of this device. Min/Max ratings are based on product characterization and simulation. Individual
parameters are tested as noted.
www.national.com 4
. No guarantee of parametric performance is indicated in the electrical tables under conditions of internal self heating where T
J=TA
>
TA.
J
Note 3: The maximum continuous output current (I
Section for more details.
Note 4: Human body model, 1.5 kΩ in series with 100 pF. Machine model, 0Ω In series with 200 pF.
) is determined by device power dissipation limitations. See the Power Dissipation section of the Application
OUT
Connection Diagrams
5-Pin SOT23 8-Pin SOIC
LMH6723/LMH6724/LMH6725
Top View
20078937
Top View
20078938
14-Pin SOIC 8-Pin SOIC
Top View
20078944
20078947
Top View
Ordering Information
Package Part Number Package Marking Transport Media NSC Drawing
5-Pin SOT23
8-Pin SOIC
8-Pin SOIC
14-Pin SOIC
LMH6723MF
LMH6723MFX 3k Units Tape and Reel
LMH6723MA
LMH6723MAX 2.5k Units Tape and Reel
LMH6724MA
LMH6724MAX 2.5k Units Tape and Reel
LMH6725MA
LMH6725MAX 2.5k Units Tape and Reel
AB1A
LMH6723MA
LMH6724MA
LMH6725MA
1k Units Tape and Reel
95 Units/Rail
95 Units/Rail
55 Units/Rail
MF05A
M08A
M08A
M14A
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Typical Performance Characteristics A
Frequency Response vs. V
LMH6723/LMH6724/LMH6725
Frequency Response vs. V
OUT,AV
OUT,AV
= 2 Frequency Response vs. V
20078928 20078926
= 1 Frequency Response vs. V
=2,RF= 1200Ω,RL= 100Ω, unless otherwise specified.
V
OUT,AV
OUT,AV
=2
=1
20078929 20078927
Large Signal Frequency Response Frequency Response vs. Supply Voltage
20078921
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20078930
LMH6723/LMH6724/LMH6725
Typical Performance Characteristics A
specified. (Continued)
Suggested R
Frequency Response vs. R
vs. Gain Non-Inverting Suggested RFvs. Gain Inverting
F
20078905
F
=2,RF= 1200Ω,RL= 100Ω, unless otherwise
V
Frequency Response vs. R
20078906
F
20078922 20078923
Open Loop Gain & Phase Open Loop Gain & Phase
20078917
20078918
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Typical Performance Characteristics A
specified. (Continued)
=2,RF= 1200Ω,RL= 100Ω, unless otherwise
V
HD2 & HD3 vs. V
LMH6723/LMH6724/LMH6725
HD2 & HD3 vs. Frequency HD2 & HD3 vs. Frequency
OUT
20078911
HD2 & HD3 vs. V
OUT
20078913
20078912 20078914
Frequency Response vs. C
L
20078925 20078924
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Frequency Response vs. C
L
LMH6723/LMH6724/LMH6725
Typical Performance Characteristics A
specified. (Continued)
Suggested R
PSRR vs. Frequency PSRR vs. Frequency
OUT
vs. C
L
20078920 20078919
=2,RF= 1200Ω,RL= 100Ω, unless otherwise
V
Suggested R
OUT
vs. C
L
20078915
Closed Loop Output Resistance CMRR vs. Frequency
20078907
20078916
20078908
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Typical Performance Characteristics A
specified. (Continued)
Differential Gain & Phase Channel Matching (LMH6724)
LMH6723/LMH6724/LMH6725
=2,RF= 1200Ω,RL= 100Ω, unless otherwise
V
20078910
Channel Matching (LMH6724) Crosstalk (LMH6724)
20078949
Channel Matching (LMH6725) Channel Matching (LMH6725)
20078948
20078946
20078940 20078941
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LMH6723/LMH6724/LMH6725
Typical Performance Characteristics A
specified. (Continued)
Crosstalk (LMH6725)
20078945
=2,RF= 1200Ω,RL= 100Ω, unless otherwise
V
www.national.com11
Application Section
GENERAL INFORMATION
The LMH6723/LMH6724/LMH6725 is a high speed current
feedback amplifier manufactured on National Semiconductor’s VIP10
polar process. LMH6723/LMH6724/LMH6725 offers a
unique combination of high speed and low quiescent supply
current making it suitable for a wide range of battery powered and portable applications that require high performance. This amplifier can operate from 4.5V to 12V nominal
supply voltages and draws only 1mA of quiescent supply
LMH6723/LMH6724/LMH6725
current at 10V supplies (
LMH6724/LMH6725 has no internal ground reference so
single or split supply configurations are both equally useful.
EVALUATION BOARDS
National Semiconductor provides the following evaluation
boards as a guide for high frequency layout and as an aid in
device testing and characterization. Many of the datasheet
plots were measured with these boards. For availability and
ordering details refer to the national web site at WWW.National.com. Use the search box to locate the product folder.
Device Package Board Part #
LMH6723MA SOIC-8 CLC730227
LMH6723MF SOT-23 CLC730216
LMH6724MA SOIC-8 CLC730036
LMH6725MA SOIC-14 CLC730231
An evaluation board is shipped when a sample request is
placed with National Semiconductor.
FEEDBACK RESISTOR SELECTION
One of the key benefits of a current feedback operational
amplifier is the ability to maintain optimum frequency response independent of gain by using appropriate values for
the feedback resistor (R
Typical Performance plots specify an R
+2V/V and
specified). Generally, lowering R
value will peak the frequency response and extend the bandwidth while increasing the value of R
quency response to roll off faster. Reducing the value of R
too far below it’s recommended value will cause overshoot,
ringing and, eventually, oscillation.
™
(Vertically Integrated PNP) complimentary bi-
±
5V typically). The LMH6723/
). The Electrical Characteristics and
F
±
5V or±2.5V power supplies (unless otherwise
of 1200Ω, a gain of
F
from it’s recommended
F
will cause the fre-
F
20078922
FIGURE 1. Frequency Response vs. R
The plot labeled "Frequency Response vs. R
LMH6723/LMH6724/LMH6725’s frequency response as R
F
" shows the
F
F
is varied (RL= 100Ω,AV= +2). This plot shows that an RFof
800Ω results in peaking. An R
of 1200Ω gives near maximal
F
bandwidth and gain flatness with good stability. Since each
application is slightly different it is worth some experimentation to find the optimal R
value of R
that produces~0.1 dB of peaking is the best
F
for a given circuit. In general a
F
compromise between stability and maximal bandwidth. Note
that it is not possible to use a current feedback amplifier with
the output shorted directly to the inverting input. The buffer
configuration of the LMH6723/LMH6724/LMH6725 requires
a 2000Ω feedback resistor for stable operation. For other
gains see the charts "R
vs. Non Inverting Gain" and "RFvs.
F
Inverting Gain". These charts provide a good place to start
when selecting the best feedback resistor value for a variety
of gain settings.
For more information see Application Note OA-13 which
describes the relationship between R
F
quency response for current feedback operational amplifiers.
The value for the inverting input impedance for the
and closed-loop fre-
F
LMH6723/LMH6724/LMH6725 is approximately 500Ω. The
LMH6723/LMH6724/LMH6725 is designed for optimum performance at gains of +1 to +5V/V and −1 to −4V/V. Higher
gain configurations are still useful, however, the bandwidth
will fall as gain is increased, much like a typical voltage
feedback amplifier.
www.national.com 12
LMH6723/LMH6724/LMH6725
Application Section (Continued)
20078905
FIGURE 2. RF vs. Non-Inverting Gain
Both plots show the value of R
required at higher gains to keep R
below the input impedance of the inverting input. This limitation applies to both inverting and non-inverting configurations. For the LMH6723/LMH6724/LMH6725 the input resistance of the inverting input is approximately 500Ω and 100Ω
is a practical lower limit for R
LMH6725 begins to operate in a gain bandwidth limited
fashion in the region where R
gains. Note that the amplifier will operate with R
below 100Ω, however results will be substantially different
than predicted from ideal models. In particular the voltage
potential between the Inverting and Non- Inverting inputs
cannot be expected to remain small.
For inverting configurations the impedance seen by the
source is R
inverting gain since R
of R
G
|| RT. For most sources this limits the maximum
G
is determined by Figure 3. The value
F
is then RF/Gain. Thus for an inverting gain of −4 V/V
the input impedance is equal to 100Ω. Using a termination
resistor this can be brought down to match a 50Ω or 75Ω
source, however, a 150Ω source cannot be matched.
versus gain. A higher RFis
F
from decreasing too far
G
. The LMH6723/LMH6724/
G
must be increased for higher
F
values well
G
ACTIVE FILTERS
When using any current feedback Operational Amplifier as
an active filter it is necessary to be careful using reactive
components in the feedback loop. Reducing the feedback
impedance, especially at higher frequencies, will almost certainly cause stability problems. Likewise capacitance on the
inverting input should be avoided. See Application Notes
OA-7 and OA-26 for more information on Active Filter applications for Current Feedback Op Amps.
When using the LMH6723/LMH6724/LMH6725 as a low
pass filter the value of R
the value recommended in the R
benefit of reducing R
can be substantially reduced from
F
is increased gain at higher frequen-
F
vs. Gain charts. The
F
cies, which improves attenuation in the stop band. Stability
problems are avoided because in the stop band additional
device bandwidth is used to cancel the input signal rather
than amplify it. The benefit of this change depends on the
particulars of the circuit design. With a high pass filter configuration reducing R
will likely result in device instability
F
and is not recommended.
20078933
FIGURE 3. RFvs. Inverting Gain
FIGURE 4. Typical Application with Suggested Supply
Bypassing
20078934
FIGURE 5. Decoupling Capacitive Loads
20078906
www.national.com13
Application Section (Continued)
DRIVING CAPACITIVE LOADS
Capacitive output loading applications will benefit from the
use of a series output resistor R
of a series output resistor, R
output under capacitive loading. The charts "Suggested
vs. Cap Load" give a recommended value for selecting
R
OUT
a series output resistor for mitigating capacitive loads. The
values suggested in the charts are selected for .5 dB or less
of peaking in the frequency response. This gives a good
compromise between settling time and bandwidth. For appli-
LMH6723/LMH6724/LMH6725
cations where maximum frequency response is needed and
some peaking is tolerable, the value of R
slightly from the recommended values.
There will be amplitude lost in the series resistor unless the
gain is adjusted to compensate; this effect is most noticeable
<
with heavy loads (R
L
150Ω).
An alternative approach is to place Rout inside the feedback
loop as shown in Figure 6. This will preserve gain accuracy,
but will still limit maximum output voltage swing.
FIGURE 6. Series Output Resistor inside feedback loop
INVERTING INPUT PARASITIC CAPACITANCE
Parasitic capacitance is any capacitance in a circuit that was
not intentionally added. It comes about from electrical interaction between conductors. Parasitic capacitance can be
reduced but never entirely eliminated. Most parasitic capacitances that cause problems are related to board layout or
lack of termination on transmission lines. Please see the
section on Layout Considerations for hints on reducing problems due to parasitic capacitances on board traces. Transmission lines should be terminated in their characteristic
impedance at both ends.
High speed amplifiers are sensitive to capacitance between
the inverting input and ground or power supplies. This shows
up as gain peaking at high frequency. The capacitor raises
device gain at high frequencies by making R
smaller. Capacitive output loading will exaggerate this effect.
One possible remedy for this effect is to slightly increase the
value of the feedback (and gain set) resistor. This will tend to
offset the high frequency gain peaking while leaving other
parameters relatively unchanged. If the device has a capacitive load as well as inverting input capacitance using a series
output resistor as described in the section on "Driving Capacitive Loads" will help.
. Figure 5 shows the use
OUT
, to stabilize the amplifier
OUT
can be reduced
OUT
G
20078935
appear
20078942
FIGURE 7. High Output Current Composite Amplifier
When higher currents are required than a single amplifier
can provide, the circuit of Figure 7 can be used. Although the
example circuit was intended for the LMH6725 quad op amp,
higher thermal efficiency can be obtained by using four
separate SOIC op amps. Careful attention to a few key
components will help get good performance from this circuit.
The first thing to note is that the buffers need slightly higher
value feedback resistors than if the amplifiers were individually configured. As well, R
and C1provide mid circuit
11
frequency compensation to further improve stability. The
composite amplifier has approximately twice the phase delay
of a single circuit. The larger values of R
as the high frequency attenuation provided by C
and R10as well
8,R9
and R
1
ensure that the circuit does not oscillate.
Resistors R
4,R5,R6
and R7are necessary to ensure even
current distribution between the amplifiers. Since they are
inside the feedback loop they have no effect on the gain of
the circuit. The circuit shown has a gain of 5. The frequency
response is shown in Figure 8.
11
www.national.com 14
20078943
FIGURE 8. Composite Amplifier Frequency Response
Application Section (Continued)
LAYOUT CONSIDERATIONS
Whenever questions about layout arise, use the evaluation
board as a guide. Evaluation boards are shipped with
sample requests.
To reduce parasitic capacitances ground and power planes
should be removed near the input and output pins. Components in the feedback loop should be placed as close to the
device as possible. For long signal paths controlled impedance lines should be used, along with impedance matching
at both ends.
Bypass capacitors should be placed as close to the device
as possible. Bypass capacitors from each rail to ground are
applied in pairs. The larger electrolytic bypass capacitors
can be located anywhere on the board, the smaller ceramic
capacitors should be placed as close to the device as possible.
POWER DISSIPATION
Follow these steps to determine the Maximum power dissipation for the LMH6723/LMH6724/LMH6725:
1. Calculate the quiescent (no-load) power: P
S)VS
=V+-V
(V
-
AMP=ICC
2. Calculate the RMS power dissipated in the output stage:
(rms) = rms ((VS-V
P
D
OUT
)*I
) where V
OUT
OUT
and I
OUT
are the voltage and current across the external load and
is the total supply current.
V
S
3. Calculate the total RMS power: P
T=PAMP+PD
The maximum power that the LMH6723/LMH6724/
LMH6725, package can dissipate at a given temperature
can be derived with the following equation:
= (150o-T
P
MAX
ture (˚C) and θ
)/ θJA, where T
AMB
= Thermal resistance, from junction to
JA
= Ambient tempera-
AMB
ambient, for a given package (˚C/W). For the SOIC-8 package θ
has a θ
is 166˚C/W, for the SOT it is 230˚C/W. The SOIC-14
JA
of 130˚C/W,
JA
LMH6723/LMH6724/LMH6725
*
VIDEO PERFORMANCE
The LMH6723/LMH6724/LMH6725 has been designed to
provide good performance with both PAL and NTSC composite video signals. The LMH6723/LMH6724/LMH6725 is
specified for PAL signals. NTSC performance is typically
marginally better due to the lower frequency content of the
signal. Performance degrades as the loading is increased,
therefore best performance will be obtained with back terminated loads. The back termination reduces reflections from
the transmission line and effectively masks transmission line
and other parasitic capacitances from the amplifier output
stage. Figure 4 shows a typical configuration for driving a
75Ω Cable. The amplifier is configured for a gain of two to
make up for the 6dB of loss in R
OUT
.
SINGLE 5V SUPPLY VIDEO
With a 5V supply the LMH6723/LMH6724/LMH6725 is able
to handle a composite NTSC video signal, provided that the
signal is AC coupled and level shifted so that the signal is
centered around V
/2.
CC
ESD PROTECTION
The LMH6723/LMH6724/LMH6725 is protected against
electrostatic discharge (ESD) on all pins. The LMH6723/
LMH6725 will survive 2000V Human Body model or 200V
Machine model events.
Under closed loop operation the ESD diodes have no effect
on circuit performance. There are occasions, however, when
the ESD diodes will be evident. If the LMH6723/LMH6724/
LMH6725 is driven into a slewing condition the ESD diodes
will clamp large differential voltages until the feedback loop
restores closed loop operation. Also if the device is powered
down and a large input signal is applied the ESD diodes will
conduct.
www.national.com15
Physical Dimensions inches (millimeters)
unless otherwise noted
LMH6723/LMH6724/LMH6725
5-Pin SOT23
NS Product Number MF05A
8-Pin SOIC
NS Product Number M08A
www.national.com 16
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
LMH6723/LMH6724/LMH6725 Single/Dual/Quad 370 MHz 1 mA Current Feedback Op Amp
14-Pin SOIC
NS Product Number M14A
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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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