LM6181IM National Semiconductor, LM6181IM Datasheet - Page 22

• Manufacturer Part Number: LM6181IM
• Description: IC AMP CURR FEEDBK 100MHZ 16SOIC
• Manufacturer: National Semiconductor
• Series: VIP™ IIr

Specifications of LM6181IM

• Amplifier Type: Current Feedback
• Number Of Circuits: 1
• Slew Rate: 2000 V/µs
• -3db Bandwidth: 100MHz
• Current - Input Bias: 5µA
• Voltage - Input Offset: 3500µV
• Current - Supply: 7.5mA
• Current - Output / Channel: 130mA
• Voltage - Supply, Single/dual (±): 7 V ~ 32 V, ±3.5 V ~ 16 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• Gain Bandwidth Product: -
• Other names: *LM6181IM

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Typical Applications
FIGURE 3. Increasing Compensation
FIGURE 4. Reducing R
Closed Loop Gains, R
with Increasing R
3b: R
3a: R
f
f
= 1640Ω
= 820Ω
(Continued)
f
f
for Large
= 500Ω
f
01132817
01132816
01132815
22
SLEW RATE CONSIDERATIONS
The slew rate characteristics of current feedback amplifiers
are different than traditional voltage feedback amplifiers. In
voltage feedback amplifiers slew rate limiting or non-linear
amplifier behavior is dominated by the finite availability of the
1st stage tail current charging the compensation capacitor.
The slew rate of current feedback amplifiers, in contrast, is
not constant. Transient current at the inverting input deter-
mines slew rate for both inverting and non-inverting gains.
The non-inverting configuration slew rate is also determined
by input stage limitations. Accordingly, variations of slew
rates occur for different circuit topologies.
DRIVING CAPACITIVE LOADS
The LM6181 can drive significantly larger capacitive loads
than many current feedback amplifiers. Although the
LM6181 can directly drive as much as 100 pF without oscil-
lating, the resulting response will be a function of the feed-
back resistor value. Figure 5 illustrates the small-signal
pulse response of the LM6181 while driving a 50 pF load.
Ringing persists for approximately 70 ns. To achieve pulse
responses with less ringing either the feedback resistor can
be increased (see typical curves Suggested R
C
works well). Either technique, however, results in lowering
the system bandwidth.
Figure 6 illustrates the improvement obtained with using a
47Ω isolation resistor.
L
), or resistive isolation can be used (10Ω–51Ω typically
Drive 50 pF of Load Capacitance with 70 ns
FIGURE 5. A
of Ringing Resulting in Pulse Response
V
= −1, LM6181 Can Directly
5b
5a
01132818
f
and R
01132819
s
for