AD5546/AD5556

Data Sheet

Rev. D | Page 14 of 20

Table 10. AD5546 Output vs. Code

D in Binary

1111 1111 1111 1111

1000 0000 0000 0001

1000 0000 0000 0000

0

0111 1111 1111 1111

0000 0000 0000 0000

AC REFERENCE SIGNAL ATTENUATOR

Besides handling digital waveforms decoded from parallel input

data, the AD5546/AD5556 handle equally well low frequency

ac reference signals for signal attenuation, channel equalization,

and waveform generation applications. The maximum signal

range can be up to ±18 V (see Figure 22).

SYSTEM CALIBRATION

The initial accuracy of the system can be adjusted by trimming

the voltage reference ADR0x with a digital potentiometer (see

Figure 23). The AD5170 provides an OTP (one time program-

mable), 8-bit adjustment that is ideal and reliable for such cali-

bration. The Analog Devices, Inc., OTP digital potentiometer

comes with programmable software that simplifies the factory

calibration process.

16/14-BIT

VDD

ROFS

ROFSA

VOUT

RFB

RFBA

C6

GND

U1

AD5546/AD5556

IOUT

R2

R1

RCOMA

R1A

16/14 DATA

VREFA

U2B

OP2177

–

+

C4

1

F

C5

0.1

F

C8

1

F

C9

0.1

F

+15V

–15V

WR

WR

LDAC

LDAC

RS

RS

MSB

MSB

C2

0.1

F

C1

1

F

V+

V–

U2A

OP2177

+

–

C7

+5V

+10V

–10V

Figure 22. Signal Attenuator with AC Reference

C8

0.1µF

C9

1µF

–5V

16-/14-BIT

DATA

16-/14-BIT

DATA

2

+5V

5

6

4

GND

TRIM

U3

ADR03

R3

470kΩ

U4

AD5170

10kΩ

B

R7

1kΩ

VOUT

0V TO +2.5V

C6

GND

U1

AD5546/AD5556

R2

R1

R1A

+2.5V

VREFA

U2B

AD8628

–

+

C4

1µF

C5

0.1µF

+5V

WR

WR

LDAC

LDAC

RS

RS

MSB

MSB

C2

0.1µF

C1

1µF

C3

0.1µF

V+

V–

U2A

AD8628

+

–

C7

–2.5V

V+

V–

Figure 23. Full Span Calibration