AD5556 Analog Devices, AD5556 Datasheet - Page 12

• Manufacturer Part Number: AD5556
• Description: Current-Output Parallel-Input, 14-Bit Digital-to-Analog Converter
• Manufacturer: Analog Devices

Specifications of AD5556

• Resolution (bits): 14bit
• Dac Update Rate: 2MSPS
• Dac Settling Time: 500ns
• Max Pos Supply (v): +5.5V
• Single-supply: Yes
• Dac Type: Current Out
• Dac Input Format: Par

AD5546/AD5556
APPLICATIONS INFORMATION
UNIPOLAR MODE
Two-Quadrant Multiplying Mode, V
The AD5546/AD5556 DAC architecture uses a current-steering
R-2R ladder design that requires an external reference and op
amp to convert the unipolar mode of output voltage to
AD5546
AD5556
where D is the decimal equivalent of the input code.
The output voltage polarity is opposite to the V
this case (see Figure 19). Table 8 shows the negative output vs.
code for the AD5546.
Table 8. AD5546 Unipolar Mode Negative Output vs. Code
D in Binary
1111 1111 1111 1111
1000 0000 0000 0000
0000 0000 0000 0001
0000 0000 0000 0000
V
V
OUT
OUT
= –V
= –V
REF
REF
+5V
× D/65,536
× D/16,384
1µF
C1
0.1µF
C2
V
–V
–V
–V
0
16-/14-BIT
OUT
0.1µF
LDAC
DATA
REF
REF
REF
MSB
WR
C3
RS
V
ADR03
GND
(V)
(65,535/65,536)
/2
(1/65,536)
IN
2
U3
4
TRIM
V
OUT
Figure 19. Unipolar Two-Quadrant Multiplying Mode, V
OUT
5
= 0 V to –V
V
DD
R1
AD5546/AD5556
WR
REF
polarity in
LDAC
R
U1
COM
REF
RS
R2
MSB
Rev. D | Page 12 of 20
(1)
(2)
REF
R
R
OFS
Two-Quadrant Multiplying Mode, V
The AD5546/AD5556 are designed to operate with either
positive or negative reference voltages. As a result, positive
output can be achieved with an additional op amp, (see
Figure 20), and the output becomes
AD5546
AD5556
Table 9 shows the positive output vs. code for the AD5546.
Table 9. AD5546 Unipolar Mode Positive Output vs. Code
D in Binary
1111 1111 1111 1111
1000 0000 0000 0000
0000 0000 0000 0001
0000 0000 0000 0000
OFS
16-/14-BIT
DATA
V
V
OUT
OUT
R
R
FB
FB
GND
= +V
= +V
OUT
= 0 to –V
REF
REF
I
OUT
× D/65,536
× D/16,384
REF
C6
2.2pF
–
AD8628
+
–5V
V+
V–
U2
V
+V
+V
+V
0
OUT
0.1µF
REF
REF
REF
1µF
C4
C5
(V)
(65,535/65,536)
/2
(1/65,536)
–2.5V TO 0V
OUT
VOUT
= 0 V to +V
Data Sheet
REF
(3)
(4)