AD628

Rev. F | Page 17 of 20

5

1

3

4

8

2

7

+Vs

–Vs

6

–IN

+IN

100kΩ

10kΩ

100kΩ

10kΩ

10kΩ

A1

A2

4

5

6

3

1

2

SCLK

SDATA

CS

GND

VDD

AD628

SERIAL DATA

REF195

+12V

2

3

4

6

10μF

0.1μF

10μF

0.1μF

10μF

0.1μF

10μF

0.1μF

AD7940

+/–10V

15nF

2

3

1 AD8606

1/2

49.9Ω

33nF

+12V

–12V

10kΩ

10kΩ

AD628 REFERENCE VOLTAGE

10kΩ

15kΩ

AD8606

2/2

5

6

7

4

8

Figure 32. Level Shifter

CURRENT LOOP RECEIVER

Analog data transmitted on a 4 to 20 mA current loop can be

detected with the receiver shown in Figure 33. The AD628 is an

ideal choice for such a function because the current loop is

driven with a compliance voltage sufficient to stabilize the loop,

and the resultant common-mode voltage often exceeds com-

monly used supply voltages. Note that with large shunt values, a

resistance of equal value must be inserted in series with the

inverting input to compensate for an error at the noninverting

input.

MONITORING BATTERY VOLTAGES

Figure 34 illustrates how the AD628 is used to monitor a battery

charger. Voltages approximately eight times the power supply

voltage can be applied to the input with no damage. The resistor

divider action is well-suited for the measurement of many

power supply applications, such as those found in battery

chargers or similar equipment.

6

8

1

4

5

7

2

3

AD628

+15V

+2.5V

9.53k

Ω

–15V

10k

Ω

0V TO 5V

TO ADC

I = 4 TO 20mA

100k

Ω

210k

Ω

100k

Ω

100k

Ω

249

Ω

10k

Ω

10k

Ω

249

Ω

Figure 33. Level Shifter for 4 to 20 mA Current Loop