lm6118 National Semiconductor Corporation, lm6118 Datasheet - Page 6

• Manufacturer Part Number: lm6118
• Description: Fast Settling Dual Operational Amplifiers
• Manufacturer: National Semiconductor Corporation

www.national.com
Typical Performance Characteristics
Amplifier to Amplifier Coupling
Step Response, Av = +1, Vs =
Application Information
General
The LM6118/LM6218 are high-speed, fast-settling dual
op-amps. To insure maximum performance, circuit board lay-
out is very important. Minimizing stray capacitance at the in-
puts and reducing coupling between the amplifier’s input and
output will minimize problems.
Supply Bypassing
To assure stability, it is recommended that each power sup-
ply pin be bypassed with a 0.1 µF low inductance capacitor
near the device. If high frequency spikes from digital circuits
or switching supplies are present, additional filtering is rec-
ommended. To prevent these spikes from appearing at the
output, R-C filtering of the supplies near the device may be
necessary.
Power Dissipation
These amplifiers are specified to 20 mA output current. If ac-
companied with high supply voltages, relatively high power
dissipation in the device will occur, resulting in high junction
temperatures. In these cases the package thermal resis-
tance must be taken into consideration. (See Note 5 under
Electrical Characteristics.) For high dissipation, an N pack-
age with large areas of copper on the pc board is recom-
mended.
DS010254-23
±
15V
DS010254-8
Settling Time, Vs =
Step Response, Av = −1, Vs =
(Continued)
6
Amplifier Shut Down
If one of the amplifiers is not used, it can be shut down by
connecting both the inverting and non-inverting inputs to the
V− pin. This will reduce the power supply current by approxi-
mately 25%.
Capacitive Loading
Maximum capacitive loading is about 50 pF for a closed-loop
gain of +1, before the amplifier exhibits excessive ringing
and becomes unstable. A curve showing maximum capaci-
tive loads, with different closed-loop gains, is shown in the
Typical Performance Characteristics section.
To drive larger capacitive loads at low closed-loop gains, iso-
late the amplifier output from the capacitive load with 50 .
Connect a small capacitor directly from the amplifier output
to the inverting input. The feedback loop is closed from the
isolated output with a series resistor to the inverting input.
±
15V
±
15V
DS010254-9
DS010254-7