LMP7718MME/NOPB National Semiconductor, LMP7718MME/NOPB Datasheet - Page 17

• Manufacturer Part Number: LMP7718MME/NOPB
• Description: IC OP AMP PREC DUAL 88MHZ 8-MSOP
• Manufacturer: National Semiconductor
• Series: LMP®, PowerWise®r

Specifications of LMP7718MME/NOPB

• Amplifier Type: General Purpose
• Number Of Circuits: 2
• Output Type: Rail-to-Rail
• Slew Rate: 35 V/µs
• Gain Bandwidth Product: 88MHz
• Current - Input Bias: 0.1pA
• Voltage - Input Offset: 10µV
• Current - Supply: 1.3mA
• Current - Output / Channel: 60mA
• Voltage - Supply, Single/dual (±): 1.8 V ~ 5.5 V, ±0.9 V ~ 2.75 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• -3db Bandwidth: -
• Other names: LMP7718MME

For large signal response the rise and fall times are dominat-
ed by the slew rate of the op amps. Even though both parts
are quite similar the LMP7717 will give rise and fall times
about 2.5 times faster than the LMP7715. This is possible
because the LMP7717 is a decompensated op amp and even
though it is being used at a gain of −1, the speed is preserved
by using a good technique for external compensation.
FIGURE 10. LMP7715 Response
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17
Non-Inverting Compensation
For the non-inverting amp the same theory applies for estab-
lishing the needed compensation. When setting the inverting
configuration for a gain of −1, F has a value of 2. For the non-
inverting configuration both F and the actual gain are the
same, making the non-inverting configuration more difficult to
compensate. Using the same circuit as shown in
setting up the circuit for non-inverting operation (gain of +2)
results in similar performance as the inverting configuration
with the inputs set to half the amplitude to compensate for the
additional gain.
The response shown in
shown in
non-inverting configuration. Decreasing the value of R
around 200Ω can decrease the negative overshoot but will
have slightly longer rise and fall times. The other option is to
add a small resistor in series with the input signal.
shows the performance of the LMP7715 with no compensa-
tion. Again the decompensated parts are almost 2.5 times
faster than the fully compensated op amp.
The most difficult op amp configuration to stabilize is the gain
of +1. With proper compensation the LMP7717/LMP7718 can
be used in this configuration and still maintain higher speeds
FIGURE 11. R
FIGURE 12. LMP7715 Response Gain = +2
Figure
Figure 11
9. The part is actually slightly faster in the
C
= 240Ω and C = 2.2 nF, Gain = +2
Figure 11
below shows the results.
is close to the response
Figure
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30010882
Figure 12
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4, but
C
to