LMP7721MAX/NOPB National Semiconductor, LMP7721MAX/NOPB Datasheet - Page 12

• Manufacturer Part Number: LMP7721MAX/NOPB
• Description: IC AMP PREC 3FA BIAS CURR 8SOIC
• Manufacturer: National Semiconductor
• Series: LMP®, PowerWise®r

Specifications of LMP7721MAX/NOPB

• Amplifier Type: General Purpose
• Number Of Circuits: 1
• Output Type: Rail-to-Rail
• Slew Rate: 12.8 V/µs
• Gain Bandwidth Product: 17MHz
• Current - Input Bias: 0.003pA
• Voltage - Input Offset: 26µV
• 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-SOIC (3.9mm Width)
• For Use With: LMP7721MAEVAL - BOARD EVALUATION FOR LMP7721
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• -3db Bandwidth: -
• Other names: LMP7721MAX

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Application Information
ADVANTAGES OF THE LMP7721
Ultra Low Input Bias Current
The LMP7721 has the industry’s lowest guaranteed input bias
current. The ultra low input bias current is typically 3 fA, with
a guaranteed limit of ±20 fA at 25°C, ±900 fA at 85°C and
±5 pA at 125°C when V
supply.
Wide Bandwidth at Low Supply Current
The LMP7721 is a high performance amplifier that provides
a 17 MHz unity gain bandwidth while drawing only 1.3 mA of
current. This makes the LMP7721 ideal for wideband ampli-
fication in portable applications.
Low Input Referred Noise
The LMP7721 has a low input referred voltage noise density
(6.5 nV
ensures a very low input referred current noise density (0.01
pA/
The low input referred noise and the ultra low input bias cur-
rent make the LMP7721 stand out in maintaining signal fideli-
ty. This quality makes the LMP7721 a suitable candidate for
sensor based applications.
Low Supply Voltage
The LMP7721 has performance guaranteed at 2.5V and 5V
power supplies. The LMP7721 is guaranteed to be functional
at all supply voltages between 2.0V to 5.5V, for ambient tem-
peratures ranging from −40°C to 125°C. This means that the
LMP7721 has a long operational span over the battery's life-
time. The LMP7721 is also guaranteed to be functional at
1.8V supply voltage, for ambient temperatures ranging from
0°C to 125°C. This makes the LMP7721 ideal for use in low
voltage commercial applications.
RRO and Ground Sensing
Rail-to-rail output swing provides the maximum possible out-
put dynamic range. This is particularly important when oper-
ating at low supply voltages. An innovative positive feedback
scheme is created to boost the LMP7721’s output current
drive capability. This allows the LMP7721 to source 30 mA to
40 mA of current at 1.8V power supply.
).
Output Swing Low vs. Supply Voltage
at 1 kHz with 5V supply). Its MOS input stage
CM
= 1V with a 5V or a 2.5V power
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The LMP7721’s input common mode range includes the neg-
ative supply rail which makes direct sensing at ground possi-
ble in single supply operation.
Unique Pinout
The LMP7721 has been designed with the IN+ and IN−, V
and V
lation pins between IN+ and V
pinout makes it easy to guard the LMP7721’s input. This
pinout design reduces the input bias current’s dependence on
common mode or supply bias.
The SOIC package features low leakage and it has large pin
spacing. This lowers the probability of dust particles settling
down between two pins thus reducing the resistance between
the pins which can be a problem.
Input Protection
The LMP7721 input stage is protected from seeing excessive
differential input voltage by a pair of back-to-back diodes at-
tached between the inputs. This limits the differential voltage
and hence prevents phase inversion as well as any perfor-
mance drift. These diodes can conduct current when the input
signal has a really fast edge, and, if necessary, should be
isolated (using a resistor or a current follower) in such cases.
SYSTEM DESIGN TECHNIQUES WITH THE LMP7721
In order to take full advantage of the LMP7721’s ultra low input
bias current, a triaxial cable/connector is recommended when
designing application systems.
A triaxial cable/connector is similar to a coaxial cable/con-
nector and is often referred to as “triax”. Figure 1 shows the
structure of the triax.
−
pins on opposite sides of the package. There are iso-
FIGURE 1. The Structure of a Triax
−
, IN− and V+. This unique
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