LMV552MM National Semiconductor, LMV552MM Datasheet - Page 9

• Manufacturer Part Number: LMV552MM
• Description: OP AMP, RRO, DUAL, 3MHZ, SMD, MSOP8
• Manufacturer: National Semiconductor

Specifications of LMV552MM

• Op Amp Type: Low Power
• No. Of Amplifiers: 1
• Bandwidth: 3MHz
• Slew Rate: 1V/µs
• Supply Voltage Range: 2.7V To 5.5V
• Amplifier Case Style: MSOP
• No. Of Pins: 8
• Operating Temperature Range: -40°C To
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Applications Information
ADVANTAGES OF THE LMV551/LMV552
Low Voltage and Low Power Operation
The LMV551/LMV552 have performance guaranteed at sup-
ply voltages of 3V and 5V and are guaranteed to be opera-
tional at all supply voltages between 2.7V and 5.5V. For this
supply voltage range, the LMV551 draws the extremely low
supply current of less than 37 μA.
Wide Bandwidth
The LMV551's bandwidth to power ratio of 3 MHz to 37 μA
per amplifier is one of the best bandwidth to power ratios ever
achieved. This makes these devices ideal for low power sig-
nal processing applications such as portable media players
and instrumentation.
Low Input Referred Noise
The LMV551/LMV552 provide a flatband input referred volt-
age noise density of 70 nV/
than the noise performance expected from an ultra low power
op amp. They also feature the exceptionally low 1/f noise cor-
ner frequency of 4 Hz. This noise specification makes the
LMV551/LMV552 ideal for low power applications such as
PDAs and portable sensors.
Ground Sensing and Rail-to-Rail Output
The LMV551/LMV552 each have a rail-to-rail output stage,
which provides the maximum possible output dynamic range.
This is especially important for applications requiring a large
output swing. The input common mode range includes the
negative supply rail which allows direct sensing at ground in
a single supply operation.
Small Size
The small footprints of the LMV551/LMV552 packages save
space on printed circuit boards, and enable the design of
smaller and more compact electronic products. Long traces
between the signal source and the op amp make the signal
path susceptible to noise. By using a physically smaller pack-
age, the amplifiers can be placed closer to the signal source,
reducing noise pickup and enhancing signal integrity
Negative Output Swing vs. Supply Voltage
, which is significantly better
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STABILITY OF OP AMP CIRCUITS
Stability and Capacitive Loading
As seen in the Phase Margin vs. Capacitive Load graph, the
phase margin reduces significantly for C
pF. This is because the op amp is designed to provide the
maximum bandwidth possible for a low supply current. Sta-
bilizing them for higher capacitive loads would have required
either a drastic increase in supply current, or a large internal
compensation capacitance, which would have reduced the
bandwidth of the op amp. Hence, if the LMV551/LMV552 are
to be used for driving higher capacitive loads, they will have
to be externally compensated.
An op amp, ideally, has a dominant pole close to DC, which
causes its gain to decay at the rate of 20 dB/decade with re-
spect to frequency. If this rate of decay, also known as the
rate of closure (ROC), remains the same until the op amp’s
unity gain bandwidth, the op amp is stable. If, however, a large
capacitance is added to the output of the op amp, it combines
with the output impedance of the op amp to create another
pole in its frequency response before its unity gain frequency
(Figure 1). This increases the ROC to 40 dB/ decade and
causes instability.
FIGURE 1. Gain vs. Frequency for an Op Amp
L
greater than 100
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