Datasheet

AD5546/AD5556 Data Sheet
Rev. D | Page 14 of 20
Table 10. AD5546 Output vs. Code
D in Binary V
OUT
1111 1111 1111 1111 +V
REF
(32,767/32,768)
1000 0000 0000 0001 +V
REF
(1/32,768)
1000 0000 0000 0000 0
0111 1111 1111 1111 –V
REF
(1/32,768)
0000 0000 0000 0000 –V
REF
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.
03810-0-024
16/14-BIT
VDD
ROFS
ROFSA
VOUT
RFB
RFBA
C6
GND
U1
AD5546/AD5556
IOUT
R2R1
RCOMAR1A
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
03810-025
16-/14-BIT
DATA
16-/14-BIT
DATA
2
+5V
5
6
4
GND
V
IN
TRIM
U3
ADR03
V
OUT
V
DD
R
OFS
R3
470kΩ
U4
AD5170
10kΩ
B
R7
1kΩ
R
OFSA
VOUT
0V TO +2.5V
R
FB
R
FBA
C6
GND
U1
AD5546/AD5556
I
OUT
R2R1
R
COMA
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