5

250

Ω) in the I

250

Ω) between the reference voltage and the V

REF

terminal.

Bipolar (Offset Binary) Operation

The circuit configuration for operating the AD7533 in the

bipolar mode is given in Figure 3. Using offset binary digital

input codes and positive and negative reference voltage

values, 4-Quadrant multiplication can be realized. The

“Digital Input Code/Analog Output Value” table for bipolar

mode is given in Table 2.

A “Logic 1” input at any digital input forces the

corresponding ladder switch to steer the bit current to

complements of one another. The current amplifier at

currents. This configuration doubles the output range. The

difference current resulting at zero offset binary code,

(MSB = “Logic 1”, all other bits = “Logic 0”), is corrected by

using an external resistor, (10M

Offset Adjustment

6. Connect all digital inputs to “Logic 1”.

8. Connect MSB (Bit 1) to “Logic 1” and all other bits to

“Logic 0”.

Gain Adjustment

1. Connect all digital inputs to V+.

250

Ω between V

250

Ω between the reference voltage and the V

REF

terminal.

6

6

-

+

CR1

15

16

1

4

13

3

2

MSB

LSB

14

+15V

DATA

INPUTS

AD7533

±10V

R3 5K

R4 5K

R2

CR2

R1

R6 10M

Ω

FIGURE 3. BIPOLAR OPERATION (4-QUADRANT MULTIPLICATION)

-

+

TABLE 2. UNlPOLAR BINARY CODE - AD7533

DIGITAL INPUT

MSB

LSB

(NOTE 2)

NOMINAL ANALOG OUTPUT

1111111111

1000000001

1000000000

0

0111111111

0000000001

0000000000

NOTES:

13. Nominal Full Scale for the circuit of Figure 3 is given by:

.

14. Nominal LSB magnitude for the circuit of Figure 3 is given by:

.

-V

REF

511

512

----------





-V

REF

1

512

----------





+V

REF

1

512

----------





+V

REF

511

512

----------





+V

REF

512

512

----------





FSR

V

REF

1023

512

-------------





=

LSB

V

REF

1

512

----------





=

AD7533