AD7528
V
A
IN
(± 10V)
Table I. Unipolar Binary Code Table
1
R1
DAC Latch Contents Analog Output
1
R2
MSB
LSB
(DAC A or DAC B)
V
DD
2
R
A
C1
FB
255
–VIN
DB0
1 1 1 1 1 1 1 1
1 0 0 0 0 0 0 1
1 0 0 0 0 0 0 0
0 1 1 1 1 1 1 1
0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0
INPUT
BUFFER
DATA
INPUTS
256
V
A
DAC A
OUTA
AGND
LATCH
OUT
DB7
129
–VIN
AGND
256
AD7528
1
VIN
2
128
256
R4
DAC A/
–VIN
–VIN
–VIN
–VIN
= −
DAC B
2
CONTROL
LOGIC
R
B
C2
FB
CS
127
256
WR
OUT B
LATCH
DAC B
R3
V
B
OUT
DGND
1
256
AGND
1
0
256
= 0
V
B
IN
(± 10V)
NOTES:
1
R1, R2 AND R3, R4 USED ONLY IF GAIN ADJUSTMENT IS REQUIRED.
SEE TABLE III FOR RECOMMENDED VALUES.
C1, C2 PHASE COMPENSATION (10pF–15pF) IS REQUIRED WHEN
USING HIGH SPEED AMPLIFIERS TO PREVENT RINGING OR OSCILLATION.
1
256
2−8
V
(
)
=
V
(
Note: 1 LSB =
)
)
(
IN
IN
2
Figure 4. Dual DAC Unipolar Binary Operation
(2 Quadrant Multiplication); See Table I
V
A
IN
Table II. Bipolar (Offset Binary) Code Table
DAC Latch Contents Analog Output
(± 10V)
R5
20k⍀
2
R6
1
R1
20k⍀
MSB
LSB
(DAC A or DAC B)
2
R7
V
A
A2
OUT
1
R2
10k⍀
127
+VIN
1 1 1 1 1 1 1 1
1 0 0 0 0 0 0 1
1 0 0 0 0 0 0 0
0 1 1 1 1 1 1 1
0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0
V
3
DD
128
C1
R
A
R11
5k⍀
FB
DB0
INPUT
BUFFER
DATA
INPUTS
A1
AGND
DAC A
OUTA
AGND
LATCH
DB7
0
AGND
AD7528
1
R4
B
DAC A/
1
–VIN
DAC B
3
CONTROL
LOGIC
R
C2
FB
CS
128
WR
R8
20k⍀
LATCH
DAC B
R3
OUT B
AGND
A3
127
–VIN
2
R9
DGND
128
10k⍀
128
–VIN
2
A4
V
B
R10
OUT
1
128
20k⍀
R12
1
128
2−7
V
(
)
=
V
(
5k⍀
V
B
Note: 1 LSB =
)
)
(
IN
IN
IN
AGND
(± 10V)
NOTES:
1
R1, R2 AND R3, R4 USED ONLY IF GAIN ADJUSTMENT IS REQUIRED.
SEE TABLE III FOR RECOMMENDED VALUES.
ADJUST R1 FOR V
ADJUST R3 FOR V
MATCHING AND TRACKING IS ESSENTIAL FOR RESISTOR PAIRS
R6, R7 AND R9, R10.
C1, C2 PHASE COMPENSATION (10pF–15pF) MAY BE REQUIRED
IF A1/A3 IS A HIGH SPEED AMPLIFIER.
A = 0V WITH CODE 10000000 IN DAC A LATCH.
B = 0V WITH CODE 10000000 IN DAC B LATCH.
OUT
OUT
2
3
Table III. Recommended Trim Resistor
Values vs. Grade
Trim
Resistor
Figure 5. Dual DAC Bipolar Operation
(4 Quadrant Multiplication); See Table II
J/A/S
K/B/T
L/C/U
R1; R3
R2; R4
1 k
330
500
150
200
82
REV. B
–5–
ROCHESTER [ Rochester Electronics ]
