5

Applications

Unipolar Binary Operation

The circuit configuration for operating the AD7520 in

unipolar mode is shown in Figure 8. Similar circuits can be

the circuit is capable of 2-Quadrant multiplication. The Digital

Input Code/Analog Output Value table for unipolar mode is

given in Table 1.

Zero Offset Adjustment

1. Connect all digital inputs to GND.

2. Adjust the offset zero adjust trimpot of the output

Gain Adjustment

1. Connect all digital inputs to V+.

AD7520 and N = 10 for AD7521).

FIGURE 4. NOISE

FIGURE 5. OUTPUT CAPACITANCE

FIGURE 6. FEEDTHROUGH ERROR

FIGURE 7. OUTPUT CURRENT SETTLING TIME

15

2

5

4

13 3 1

AD7520

101ALN

-

+

0.1

µF

14

10k

Ω

100

Ω

15

µF

1K

+15V

50k

Ω

1k

Ω

-50V

f = 1kHz

BW = 1Hz

QUAN

TECH

MODEL 134D

WAVE

ANALYZER

15

16

1

5

4

13 3

2

AD7520

BIT 1 (MSB)

BIT 10 (LSB)

14

+15V

NC

SCOPE

1MHz

NC

1k

Ω

+15V

15

16

1

5

4

13 3

2

AD7520

BIT 1 (MSB)

BIT 10 (LSB)

14

+15V

GND

2

3

6

100kHz SINE WAVE

HA2600

-

+

15

1

5

4

13 3

2

AD7520

BIT 1 (MSB)

BIT 10 (LSB)

14

+15V

SCOPE

+100mV

100

Ω

GND

DIGITAL

EXTRAPOLATE

5t: 1% SETTLING (1mV)

8t: 0.03% SETTLING

t = RISE TIME

INPUT

+5V

0V

+10V

15

16

1

5

4

13 3

2

AD7520

BIT 1 (MSB)

BIT 10 (LSB)

14

+15V

GND

6

-

+

DIGITAL

INPUT

FIGURE 8. UNIPOLAR BINARY OPERATION (2-QUADRANT

MULTIPLICATION)

TABLE 1. CODE TABLE - UNlPOLAR BINARY OPERATION

DIGITAL INPUT

ANALOG OUTPUT

1111111111

1000000001

1000000000

0111111111

0000000001

0000000000

0

NOTES:

2. N = 8 for 7520

N = 10 for 7521.

AD7520, AD7521