INA331, INA2331

SBOS215B

13

www.ti.com

APPLICATION CIRCUITS

MEDICAL ECG APPLICATIONS

Figure 9 shows the INA331 configured to serve as a low-cost

ECG amplifier, suitable for moderate accuracy heart-rate

applications such as fitness equipment. The input signals are

obtained from the left and right arms of the patient. The

common-mode voltage is set by two 2M

Ω resistors. This

potential through a buffer provides optional right leg drive.

Filtering can be modified to suit application needs by chang-

ing the capacitor value of the output filter.

LOW-POWER, SINGLE-SUPPLY DATA

ACQUISITION SYSTEMS

Refer to Figure 4 to see the INA331 configured to drive an

ADS7818. Functioning at frequencies of up to 500kHz, the

INA331 is ideal for low-power data acquisition.

FIGURE 9. Simplified ECG Circuit for Medical Applications.

OPA336

OPA336

OPA336

Right Arm

Left Arm

1M

Ω

REF

1M

Ω

1M

Ω

10k

Ω

10k

Ω

2k

Ω

2k

Ω

1.6nF

0.1

µF

100k

Ω

100k

Ω

+5V

V

R

V

R

V

2M

Ω

2M

Ω

Right

Leg

INA331

5

3

2

8

7

6

4

1

V+

Shutdown

RG

V

V–

V

V

OUT PUT