INA139, INA169

8

SBOS181C

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FIGURE 6. Bipolar Current Measurement Using a Differential Input of the A/D Converter.

FIGURE 7. Multiplexed Measurement Using Logic Signal for Power.

INA169

INA169

Other INA169s

––

––

1N4148

Digital I/O on the ADS7870 provides power to

select the desired INA169. Diodes prevent

output current of an “on” INA169 from flowing

into an “off” INA169.

REF

V+

V+

R

L

Serial

I/O

ADS7870

Clock

Divider

Oscillator

BUF

OUT

BUF

IN

REF

OUT

12-Bit

A/D

Converter

BUF

MUX

Digital

I/O

PGIA

+5V

REF

Serial

I/O

ADS7870

Clock

Divider

Oscillator

BUF

OUT

BUF

IN

REF

OUT

12-Bit

A/D

Converter

BUF

MUX

Digital

I/O

PGIA

+5V

1

2

+5V

5

4

3

1

2

+5V

5

4

3

R

S

RL

25k

Ω

RL

25k

Ω

V+

INA139

INA139

The A/D converter is programmed for differential input.

Depending on the polarity of the current, one INA139 provides

an output voltage whereas the other’s output is zero.