INA118

R

G

/2

V

O

LA

RL

RA

10k

Ref

G = 10

2.8k

2.8k

1/2

OPA2604

390k

390k

1/2

OPA2604

A

I

1

OPA177

–1.5nA

OPA602

–1pA

OPA128

–75fA

INA118

R

G

I

B

R

V

–

1

IN

+

A

1

I

Load

O

I =

• G

O

V

R

IN

1

Ref

INA118

SBOS027A – SEPTEMBER 2000 – REVISED JANUARY 2016

www.ti.com

Low Voltage Operation (continued)

Figure 33. Differential Voltage to Current Converter

Figure 34. ECG Amplifier With Right-Leg Drive

9.2 Single Supply Operation

The INA118 can be used on single power supplies of 2.7 V to 36 V. Figure 35 shows a basic single supply

circuit. The output Ref terminal is connected to ground. Zero differential input voltage demands an output voltage

of 0 V (ground). Actual output voltage swing is limited to approximately 35-mV above ground, when the load is

referred to ground as shown. Figure 15 shows how the output voltage swing varies with output current.

–

possible, for example, to connect the inverting input to ground and measure a voltage connected to the

noninverting input.

To illustrate the issues affecting low voltage operation, consider the circuit in Figure 35, which shows the INA118

operating from a single 3-V supply. A resistor in series with the low side of the bridge assures that the bridge

output voltage is within the common-mode range of the amplifier’s inputs. See Figure 3 for 3-V single supply

operation.

18

Submit Documentation Feedback

Copyright © 2000–2016, Texas Instruments Incorporated

Product Folder Links: INA118