OP467
+5V
+10V
1
2
V
DD
V
REF
A
R
FB
A
I
OUT 1A
DAC8408
DGND 28
V
REF
C 27
R
FB
C 26
I
OUT 1C
25
I
OUT 2C/
I
OUT 2D
24
I
OUT 1D
23
R
FB
D 22
V
REF
D 21
DS2 20
DS1 19
R/W 18
A/B 17
+10V
C1
10pF
2
3
4
5
6
7
C3
10pF
13
OUT A
1
OP467
3
I
OUT 2A/
I
OUT 2B
I
OUT 1B
R
FB
B
V
REF
B
DB0 (LSB)
OP467
12
14
OUT D
+15V
0.1µF
4
6
9
8
C2
10pF
+10V
OUT B
7
OP467
11
5
9
+10V
C4
10pF
OP467
10
8
OUT C
0.1µF
–15V
10 DB1
11 DB2
12 DB3
13 DB4
14 DB5
DIGITAL
CONTROL
SIGNALS
(MSB) DB7 16
DB6 15
00302-050
Figure 50. Quad DAC Unipolar Operation
FAST I-TO-V CONVERTER
The fast slew rate and fast settling time of the OP467 are well
suited to the fast buffers and I-to-V converters used in a variety
of applications. The circuit in Figure 50 is a unipolar quad DAC
consisting of only two ICs. The current output of the DAC8408
is converted to a voltage by the OP467 configured as an I-to-V
converter. This circuit is capable of settling to 0.1% within 200 ns.
outputs. To obtain reliable circuit performance, keep the traces
from the I
OUT
of the DAC to the inverting inputs of the OP467
short to minimize parasitic capacitance.
260.0ns
100
90
100
90
251.0ns
10
0%
2V
50mV
100ns
Figure 52. Rising Edge Output Settling Time
DAC8408
R
FB
3pF
I
OUT
I-V
OP467
2kΩ
AD847
604Ω
1kΩ
50kΩ
2kΩ
DC OFFSET
00302-052
10
0%
00302-051
60.4kΩ
2V
50mV
100ns
Figure 53. DAC V
OUT
Settling Time Circuit
Figure 51. Falling Edge Output Settling Time
Rev. F | Page 16 of 20
00302-053
AD [ ANALOG DEVICES ]
