LM7171AIM National Semiconductor, LM7171AIM Datasheet - Page 17

• Manufacturer Part Number: LM7171AIM
• Description: IC, OP-AMP, 200MHZ, 4100V/µs, SOIC-8
• Manufacturer: National Semiconductor

Specifications of LM7171AIM

• Op Amp Type: Voltage Feedback
• No. Of Amplifiers: 1
• Bandwidth: 200MHz
• Slew Rate: 4100V/µs
• Supply Voltage Range: 5.5V To 36V
• Amplifier Case Style: SOIC
• No. Of Pins: 8
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Application Notes
ally 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 ter-
minated signal while Figure 4 shows an improperly termi-
nated signal.
FIGURE 4. Improperly Terminated Signal
FIGURE 3. Properly Terminated Signal
FIGURE 2. Power Supply Bypassing
(Continued)
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To minimize reflection, coaxial cable with matching charac-
teristic 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 ring-
ing 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 perfor-
mance 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:
Where
For example, for the LM7171 in a SO-8 package, the maxi-
mum power dissipation at 25˚C ambient temperature is
730 mW.
PD
T
T
θ
JA
J(max)
A
FIGURE 6. The LM7171 Driving a 150 pF Load
is the power dissipation in a device
is the maximum junction temperature
is the ambient temperature
is the thermal resistance of a particular package
FIGURE 5. Isolation Resistor Used
with a 50Ω Isolation Resistor
to Drive Capacitive Load
P
D
= (T
J(MAX)
− T
A
)/θ
JA
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