AD210

REV. A

–3–

INSIDE THE AD210

The AD210 basic block diagram is illustrated in Figure 1.

A +15 V supply is connected to the power port, and

±15 V isolated power is supplied to both the input and

output ports via a 50 kHz carrier frequency. The uncom-

mitted input amplifier can be used to supply gain or buff-

ering of input signals to the AD210. The fullwave

modulator translates the signal to the carrier frequency for

application to transformer T1. The synchronous demodu-

lator in the output port reconstructs the input signal. A

20 kHz, three-pole filter is employed to minimize output

noise and ripple. Finally, an output buffer provides a low

impedance output capable of driving a 2 k

Ω load.

INPUT

POWER

SUPPLY

19

14

15

16

17

18

30

29

T2

POWER

POWER

OSCILLATOR

INPUT

OUTPUT

MOD

DEMOD

FILTER

1

2

OUTPUT

POWER

SUPPLY

3

4

AD210

PWR COM

PWR

T3

T1

+IN

–IN

FB

Figure 1. AD210 Block Diagram

USING THE AD210

The AD210 is very simple to apply in a wide range of ap-

plications. Powered by a single +15 V power supply, the

AD210 will provide outstanding performance when used

as an input or output isolator, in single and multichannel

configurations.

Input Configurations:

The basic unity gain configura-

tion for signals up to

±10 V is shown in Figure 2. Addi-

tional input amplifier variations are shown in the following

figures. For smaller signal levels Figure 3 shows how to

obtain gain while maintaining a very high input impedance.

19

14

15

16

17

18

(

±10V)

30

29

±10V

AD210

+15V

2

3

4

1

Figure 2. Basic Unity Gain Configuration

The high input impedance of the circuits in Figures 2 and

3 can be maintained in an inverting application. Since the

AD210 is a three-port isolator, either the input leads or

the output leads may be interchanged to create the signal

inversion.

19

14

15

16

17

18

30

29

AD210

+15V

2

3

4

1

(

)

Figure 3. Input Configuration for G > 1

Figure 4 shows how to accommodate current inputs or sum cur-

rents or voltages. This circuit configuration can also be used for

signals greater than

±10 V. For example, a ±100 V input span

Ω and R

Ω.

19

14

15

16

17

18

30

29

AD210

+15V

2

3

4

1

(

)

+

Figure 4. Summing or Current Input Configuration

Adjustments

When gain and offset adjustments are required, the actual cir-

cuit adjustment components will depend on the choice of input

configuration and whether the adjustments are to be made at

the isolator’s input or output. Adjustments on the output side

might be used when potentiometers on the input side would

represent a hazard due to the presence of high common-mode

voltage during adjustment. Offset adjustments are best done at

the input side, as it is better to null the offset ahead of the gain.

Figure 5 shows the input adjustment circuit for use when the in-

put amplifier is configured in the noninverting mode. This offset

adjustment circuit injects a small voltage in series with the

19

15

16

17

18

30

29

AD210

+15V

2

3

4

HI

14

200

Ω

47.5k

Ω

5k

Ω

100k

Ω

50k

Ω

LO

GAIN

OFFSET

1

Figure 5. Adjustments for Noninverting Input