LMH6723MF National Semiconductor, LMH6723MF Datasheet - Page 15

• Manufacturer Part Number: LMH6723MF
• Description: OP AMP, 1MA WIDEBAND CFB, POWERWISE
• Manufacturer: National Semiconductor

Specifications of LMH6723MF

• Op Amp Type: Wideband
• No. Of Amplifiers: 1
• Bandwidth: 370MHz
• Slew Rate: 600V/µs
• Supply Voltage Range: 4.5V To 12V
• Amplifier Case Style: SOT-23
• No. Of Pins: 5
• Operating Temperature Range: -40°C To
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Application Section
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. Compo-
nents in the feedback loop should be placed as close to the
device as possible. For long signal paths controlled imped-
ance 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 pos-
sible.
VIDEO PERFORMANCE
The LMH6723/LMH6724/LMH6725 has been designed to
provide good performance with both PAL and NTSC com-
posite 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 termi-
nated 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
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
CC
/2.
OUT
(Continued)
.
15
POWER DISSIPATION
Follow these steps to determine the Maximum power dissi-
pation for the LMH6723/LMH6724/LMH6725:
1.
2. Calculate the RMS power dissipated in the output stage:
3. Calculate the total RMS power: P
The
LMH6725, package can dissipate at a given temperature
can be derived with the following equation:
P
ture (˚C) and θ
ambient, for a given package (˚C/W). For the SOIC-8 pack-
age θ
has a θ
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.
MAX
(V
P
are the voltage and current across the external load and
V
Calculate the quiescent (no-load) power: P
D
S
JA
= (150
S
maximum
) V
(rms) = rms ((V
is the total supply current.
JA
is 166˚C/W, for the SOT it is 230˚C/W. The SOIC-14
of 130˚C/W,
S
= V
o
- T
+
JA
AMB
- V
power
= Thermal resistance, from junction to
)/ θ
-
S
JA
-V
, where T
OUT
that
)*I
OUT
the
AMB
) where V
T
LMH6723/LMH6724/
= P
= Ambient tempera-
AMP
OUT
+P
AMP
www.national.com
D
and I
= I
CC
OUT
*