Datasheet

UNSTABLE

ROC = 40 dB/decade

STABLE

ROC ± 20 dB/decade

FREQUENCY (Hz)

GAIN

LMV641

www.ti.com

SNOSAW3C –SEPTEMBER 2007–REVISED FEBRUARY 2013

APPLICATION INFORMATION

ADVANTAGES OF THE LMV641

Low Voltage and Low Power Operation

The LMV641 has performance guaranteed at supply voltages of 2.7V and 10V. It is guaranteed to be operational

at all supply voltages between 2.7V and 12.0V. The LMV641 draws a low supply current of 138 µA. The LMV641

provides the low voltage and low power amplification which is essential for portable applications.

Wide Bandwidth

Despite drawing the very low supply current of 138 µA, the LMV641 manages to provide a wide unity gain

bandwidth of 10 MHz. This is easily one of the best bandwidth to power ratios ever achieved, and allows this op

amp to provide wideband amplification while using the minimum amount of power. This makes the LMV641 ideal

for low power signal processing applications such as portable media players and other accessories.

Low Input Referred Noise

The LMV641 provides a flatband input referred voltage noise density of 14 nV/ , which is significantly better

than the noise performance expected from a low power op amp. This op amp also feature exceptionally low 1/f

noise, with a very low 1/f noise corner frequency of 4 Hz. Because of this the LMV641 is ideal for low power

applications which require decent noise performance, such as PDAs and portable sensors.

Ground Sensing and Rail-to-Rail Output

The LMV641 has 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 of this part

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

Small Size

The small footprint of the packages for the LMV641 saves space on printed circuit boards, and enables 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 package, these op amps can be placed

closer to the signal source, reducing noise pickup and enhancing signal integrity.

STABILITY OF OP AMP CIRCUITS

If the phase margin of the LMV641 is plotted with respect to the capacitive load (C

) at its output, and if C

increased beyond 100 pF then the phase margin reduces significantly. This is because the op amp is designed

to provide the maximum bandwidth possible for a low supply current. Stabilizing the LMV641 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. Hence, if this device is to be used for driving higher

capacitive loads, it will have to be externally compensated.

Figure 40. Gain vs. Frequency for an Op Amp

Product Folder Links: LMV641