OP193 查看數據表（PDF） - Analog Devices
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OP193 Datasheet PDF : 16 Pages
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OP193/OP293/OP493
5V
3.6k⍀
AD589
1.23V
4 IOUT1A
5V
1
VDD
DAC A
1/4
VREFA
2
DAC8408
5V
4
2
A
1
1/4 OP493
3
VOUTA
11
R1
100k⍀
5 IOUT2A/2B
6 IOUT1B
DAC B VREFB 8
1/4
DAC8408
6
B
1/4 OP493
5
7
VOUTB
R2
100k⍀
25 IOUT1C
DAC C
1/4
VREFC 27
DAC8408
13
C
1/4 OP493
12
14
VOUTC
R3
100k⍀
A Single-Supply Micropower Quad Programmable-Gain
Amplifier
The combination of the quad OP493 and the DAC8408 quad
8-bit CMOS DAC creates a quad programmable-gain amplifier
with a quiescent supply drain of only 140 µA (Figure 14). The
digital code present at the DAC, which is easily set by a micro-
processor, determines the ratio between the fixed DAC feedback
resistor and the resistance that the DAC feedback ladder pre-
sents to the op amp feedback loop. The gain of each amplifier is:
V
256
= OUT
V
n
IN
where n equals the decimal equivalent of the 8-bit digital code
present at the DAC.
If the digital code present at the DAC consists of all zeros, the
feedback loop will be open causing the op amp to saturate. The
10 MΩ resistors placed in parallel with the DAC feedback loop
eliminates this problem with a very small reduction in gain
accuracy. The 2.5 V reference biases the amplifiers to the center
of the linear region providing maximum output swing.
24 IOUT2C/2D
23 IOUT1D
DAC D
1/4
VREFD 21
DAC8408
DAC DATA BUS
PINS 9(LSB)–16(MSB)
DAC8408ET
DGND
28
17
A/B
18
R/W
19
DS1
20
DS2
9
D
1/4 OP493
10
OP493
DIGITAL
CONTROL
SIGNALS
8
VOUTD
R4
100k⍀
Figure 13. Micropower Single-Supply Quad Voltage-
Output 8-Bit DAC
–14–
REV. B
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