Datasheet

REV. B
–12–
AD817
HIGH SPEED DAC BUFFER
The wide bandwidth and fast settling time of the AD817 make
it a very good output buffer for high speed current output D/A
converters like the AD668. As shown in Figure 38, the op amp
establishes a summing node at ground for the DAC output. The
output voltage is determined by the amplifier’s feedback resistor
(10.24 V for a 1 kΩ resistor). Note that since the DAC gener-
ates a positive current to ground, the voltage at the amplifier
output will be negative. A 100 Ω series resistor between the
noninverting amplifier input and ground minimizes the offset
effects of op amp input bias currents.
1
2
3
7
24
23
22
18
8
9
10
17
16
15
11
12
14
13
4
5
21
20
6
19
AD668
+15V
10µF
TO ANALOG
GROUND PLANE
0.1µF
1V NOMINAL
REFERENCE INPUT
10kΩ
1kΩ
100Ω
AD817
ANALOG GROUND PLANE
ANALOG
OUTPUT
ANALOG
SUPPLY
GROUND
0.1µF
10µF
–15V
+5V
1kΩ
100pF
DIGITAL
INPUTS
MSB
LSB
V
REFCOM
REFIN1
REFIN2
R
ACOM
LCOM
IBPO
V
THCOM
VTH
EE
LOAD
OUT
CC
I
Figure 38. High Speed DAC Buffer
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Pin Plastic Mini-DIP
(N-8)
0.011±0.003
(0.28±0.08)
0.30 (7.62)
REF
15 °
0 °
PIN 1
4
58
1
0.25
(6.35)
0.31
(7.87)
0.10
(2.54)
BSC
SEATING
PLANE
0.035±0.01
(0.89±0.25)
0.18±0.03
(4.57±0.76)
0.033
(0.84)
NOM
0.018±0.003
(0.46±0.08)
0.125
(3.18)
MIN
0.165±0.01
(4.19±0.25)
0.39 (9.91) MAX
8-Pin SOIC
(SO-8)
0.0098 (0.25)
0.0075 (0.19)
0.0500 (1.27)
0.0160 (0.41)
8 °
0 °
0.0196 (0.50)
0.0099 (0.25)
x 45 °
PIN 1
0.1574 (4.00)
0.1497 (3.80)
0.2440 (6.20)
0.2284 (5.80)
4
5
1
8
0.0192 (0.49)
0.0138 (0.35)
0.0500
(1.27)
BSC
0.0688 (1.75)
0.0532 (1.35)
0.0098 (0.25)
0.0040 (0.10)
0.1968 (5.00)
0.1890 (4.80)
C1707b–5–6/95
PRINTED IN U.S.A.