INA117

SBOS154A

7

MEASURING CURRENT

The INA117 can be used to measure a current by sensing the

INA117 used to measure the supply currents of a device

under test. The circuit in Figure 5 measures the output

current of a power supply. If the power supply has a sense

eliminate the voltage-drop error. Another common applica-

tion is current-to-voltage conversion, as shown in Figure 6.

FIGURE 4. Measuring Supply Currents of Device Under

Test.

380k

Ω

380k

Ω

380k

Ω

21.1k

Ω

20k

Ω

47

2

3

81

5

V–

V+

V

2

V

3

V

6

200

Ω

10

Ω

10

Ω

If offset adjust is also required,

connect to offset circuit, Figure 2.

CMR

Adjust

FIGURE 3. CMR Trim Circuit.

FIGURE 5. Measuring Power Supply Output Current.

380k

Ω

20k

Ω

380k

Ω

380k

Ω

380k

Ω

380k

Ω

380k

Ω

21.1k

Ω

47

2

3

81

5

6

R

S

R

C

I

DUT+

I

DUT–

21.1k

Ω

20k

Ω

47

2

3

81

5

V–

V+

6

R

S

V–

V+

Device

Under

Test

–V

S

+V

S

*Not needed if R is less than 20

—see text.

Ω

S

(+200V max)

(–200V max)

V

V

R

380k

Ω

380k

Ω

380k

Ω

20k

Ω

21.1k

Ω

47

2

3

81

5

6

R

S

R

I

L

V–

V+

±200V max

Load

Power Supply

Out

Sense

*R

Optional Load

Sense Connection

(see text)

V