5962-8770102RA Datasheet, PDF (5/8 Pages) Analog Devices – CMOS Dual 8-Bit Buffered Multiplying DAC

V_IN A
(± 10V)
V_DD
DB0
DATA
INPUTS
DB7
INPUT
BUFFER
R1¹
LATCH ^{DAC A}
R2¹
R_FB A
C1²
OUT A
AGND _AGND
V_OUT A
DAC A/
DAC B
CS
WR
DGND
CONTROL
LOGIC
AD7528
LATCH DAC B
R4¹
R_FB B
C2²
OUT B
AGND
V_OUT B
R3¹
V_IN B
(± 10V)
NOTES:
1_{R1, R2 AND R3, R4 USED ONLY IF GAIN ADJUSTMENT IS REQUIRED.}
SEE TABLE III FOR RECOMMENDED VALUES.
2_{C1, C2 PHASE COMPENSATION (10pF–15pF) IS REQUIRED WHEN}
USING HIGH SPEED AMPLIFIERS TO PREVENT RINGING OR OSCILLATION.
Figure 4. Dual DAC Unipolar Binary Operation
(2 Quadrant Multiplication); See Table I
AD7528
Table I. Unipolar Binary Code Table
DAC Latch Contents Analog Output
MSB LSB
(DAC A or DAC B)
11111111
10000001
10000000
01111111
00000001
00000000
–V
IN

255
256

–V
IN

129
256

–V _IN

128
256

=
− ^{V IN}
2
–V
IN

127
256

–V
IN

1
256

–V _IN

0
256

=
0
( )( ) ( ) ^{Note: 1 LSB =}
2^−8
V _IN
=
1
256
V _IN
V_DD
DB0
DATA
INPUTS
DB7
INPUT
BUFFER
DAC A/
DAC B
CS
WR
DGND
CONTROL
LOGIC
V_IN A
(± 10V)
R1¹
LATCH DAC A
AD7528
LATCH DAC B
R3¹
R2¹
R_FB A
R6²
20k⍀
R7²
10k⍀
C1³
OUT A
A1
AGND
AGND
R4¹
R_FB B
C2³
OUT B
AGND
A3
R9²
10k⍀
R10²
20k⍀
V_IN B
(± 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_OUT A = 0V WITH CODE 10000000 IN DAC A LATCH.
ADJUST R3 FOR V_OUT B = 0V WITH CODE 10000000 IN DAC B LATCH.
2_{MATCHING AND TRACKING IS ESSENTIAL FOR RESISTOR PAIRS}
R6, R7 AND R9, R10.
3_{C1, C2 PHASE COMPENSATION (10pF–15pF) MAY BE REQUIRED}
IF A1/A3 IS A HIGH SPEED AMPLIFIER.
Figure 5. Dual DAC Bipolar Operation
(4 Quadrant Multiplication); See Table II
R5
20k⍀
A2
R11
5k⍀
AGND
R8
20k⍀
A4
R12
5k⍀
AGND
V_OUT A
V_OUT B
Table II. Bipolar (Offset Binary) Code Table
DAC Latch Contents Analog Output
MSB LSB
(DAC A or DAC B)
11111111
+V
IN

127
128

10000001
10000000
0
01111111
00000001
00000000
–V
IN

1
128

–V
IN

127
128

–V
IN

128
128

( )( ) ( ) ^{Note: 1 LSB =}
2^−7
V _IN
=
1
128
V _IN
Table III. Recommended Trim Resistor
Values vs. Grade
Trim
Resistor
R1; R3
R2; R4
J/A/S
1k
330
K/B/T
500
150
L/C/U
200
82
REV. B
–5–