LMP7718MASLASHNOPB datasheet(15/42 Pages) TI2

15 / 42 page

LMP7717, LMP7718

www.ti.com

SNOSAY7H – MARCH 2007 – REVISED MARCH 2013

APPLICATION INFORMATION

ADVANTAGES OF THE LMP7717/LMP7718

Wide Bandwidth at Low Supply Current

The LMP7717/LMP7718 are high performance op amps that provide a GBW of 88 MHz with a gain of 10 while

drawing a low supply current of 1.15 mA. This makes them ideal for providing wideband amplification in data

acquisition applications.

With the proper external compensation the LMP7717 can be operated at gains of ±1 and still maintain much

faster slew rates than comparable unity gain stable amplifiers. The increase in bandwidth and slew rate is

obtained without any additional power consumption over the LMP7715.

Low Input Referred Noise and Low Input Bias Current

The LMP7717/LMP7718 have a very low input referred voltage noise density (5.8 nV/

√Hz at 1 kHz). A CMOS

input stage ensures a small input bias current (100 fA) and low input referred current noise (0.01 pA/

√Hz). This is

very helpful in maintaining signal integrity, and makes the LMP7717/LMP7718 ideal for audio and sensor based

applications.

Low Supply Voltage

The LMP7717 and the LMP7718 have performance ensured at 2.5V and 5V supply. These parts are ensured to

be operational at all supply voltages between 2.0V and 5.5V, for ambient temperatures ranging from

−40°C to

125°C, thus utilizing the entire battery lifetime. The LMP7717/LMP7718 are also ensured to be operational at

1.8V supply voltage, for temperatures between 0°C and 125°C optimizing their usage in low-voltage applications.

RRO and Ground Sensing

Rail-to-Rail output swing provides the maximum possible dynamic range. This is particularly important when

operating at low supply voltages. An innovative positive feedback scheme is used to boost the current drive

capability of the output stage. This allows the LMP7717/LMP7718 to source more than 40 mA of current at 1.8V

supply. This also limits the performance of the these parts as comparators, and hence the usage of the LMP7717

and the LMP7718 in an open-loop configuration is not recommended. The input common-mode range includes

the negative supply rail which allows direct sensing at ground in single supply operation.

Small Size

The small footprints of the LMP7717 packages and the LMP7718 packages save space on printed circuit boards,

and enable the design of smaller electronic products, such as cellular phones, pagers, or other portable systems.

Long traces between the signal source and the op amp make the signal path more susceptible to noise pick up.

The physically smaller LMP7717 or LMP7718 packages allow the op amp to be placed closer to the signal

source, thus reducing noise pickup and maintaining signal integrity.

USING THE DECOMPENSATED LMP7717

Advantages of Decompensated Op Amp

A unity gain stable op amp, which is fully compensated, is designed to operate with good stability down to gains

of ±1. The large amount of compensation does provide an op amp that is relatively easy to use; however, a

decompensated op amp is designed to maximize the bandwidth and slew rate without any additional power

consumption. This can be very advantageous.

The LMP7717/LMP7718 require a gain of ±10 to be stable. However, with an external compensation network (a

simple RC network) these parts can be stable with gains of ±1 and still maintain the higher slew rate. Looking at

the Bode plots for the LMP7717 and its closest equivalent unity gain stable op amp, the LMP7715, one can

clearly see the increased bandwidth of the LMP7717. Both plots are taken with a parallel combination of 20 pF

and 10 k

Ω for the output load.

Submit Documentation Feedback

Product Folder Links: LMP7717 LMP7718

LMP7718MA/NOPB Datasheet(PDF) 15 Page - Texas Instruments

LMP7718MA/NOPB Datasheet(HTML) 15 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

Datasheet Download

Link URL