Datasheet

ADC

PRESSURE

SENSOR

100:

2.4 k:

LMV862

OUT

TIME (0.5s/DIV)

OUT

(0.5V/DIV)

Typical Opamp

LMV862

LMV861, LMV862

www.ti.com

SNOSAZ5C –FEBRUARY 2008–REVISED MARCH 2013

Figure 49. Comparing EMI Robustness

The difference between the two types of op amps is clearly visible. The typical standard dual op amp has an

output shift (disturbed signal) larger than 1V as a result of the RF signal transmitted by the cell phone. The

LMV862, EMI hardened op amp does not show any significant disturbances. This means that the RF signal will

not disturb the signal entering the ADC when using the LMV862.

Figure 50. Pressure Sensor Application

DECOUPLING AND LAYOUT

Care must be given when creating a board layout for the op amp. For decoupling the supply lines it is suggested

that 10 nF capacitors be placed as close as possible to the op amp. For single supply, place a capacitor between

and V

−

. For dual supplies, place one capacitor between V

and the board ground, and a second capacitor

between ground and V

−

Even with the LMV861 and LMV862 inherent hardening against EMI, it is still recommended to keep the input

traces short and as far as possible from RF sources. Then the RF signals entering the chip are as low as

possible, and the remaining EMI can be, almost, completely eliminated in the chip by the EMI reducing features

of the LMV861 and LMV862.

LOAD CELL SENSOR APPLICATION

The LMV861 and LMV862 can be used for weight measuring system applications which use a load cell sensor.

Examples of such systems are: bathroom weight scales, industrial weight scales and weight measurement

devices on moving equipment such as forklift trucks.

The following example describes a typical load cell sensor application that can be used as a starting point for

many different types of sensors and applications. Applications in environments where EMI may appear would

especially benefit from the EMIRR performance of the LMV861 and LMV862.

Product Folder Links: LMV861 LMV862