AD5557 Analog Devices, AD5557 Datasheet - Page 14

• Manufacturer Part Number: AD5557
• Description: Dual Current Output, Parallel Input, 14-Bit Multiplying DACs with 4-Quadrant Resistors
• Manufacturer: Analog Devices

Specifications of AD5557

• 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

AD5547/AD5557
APPLICATIONS INFORMATION
UNIPOLAR MODE
2-Quadrant Multiplying Mode, V
The
R-2R ladder design that requires an external reference and op
amp to convert the unipolar mode of the output voltage to
where D is the decimal equivalent of the input code.
AD5547/AD5557
V
V
OUT
OUT
= −V
= −V
+5V
REF
REF
1µF
C1
× D/65,536 (AD5547)
× D/16,384 (AD5557)
DAC architecture uses a current-steering
16/14 DATA
C2
0.1µF
A0, A1
LDAC
MSB
0.1µF
4
WR
RS
C3
V
GND
IN
2
TRIM
V
OUT
OUT
U3
VDD
WR
= 0 V to –V
ADR03
Figure 21. Unipolar 2-Quadrant Multiplying Mode, V
5
6
LDAC
AD5547/AD5557
R1
R
1A
RS
U1
REF
MSB A0, A1
R
COMA
R2
V
REFA
Rev. C | Page 14 of 20
2
(1)
(2)
+2.5V
R
16-/14-BIT
OFSA
ROFS
2.5V
In this case, the output voltage polarity is opposite the V
polarity (see Figure 21). Table 7 shows the negative output vs.
code for the AD5547.
Table 7.
D in Binary
1111 1111 1111 1111
1000 0000 0000 0000
0000 0000 0000 0001
0000 0000 0000 0000
R
RFB
FBA
AGNDA
AD5547
OUT
I
OUTA
= 0 to –V
C6
Unipolar Mode Negative Output vs. Code
REF
6.8pF
AD8628
+V
–V
–5V
V
–V
–V
–V
0
C4
C5
OUT
REF
REF
REF
1µF
0.1µF
(V)
/2
(65,535/65,536)
(1/65,536)
–2.5V TO 0V
V
OUTA
Data Sheet
REF