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參數(shù)資料
| 型號： | AD7846 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | LC2MOS 16-Bit Voltage Output DAC |
| 中文描述： | LC2MOS 16位電壓輸出DAC |
| 文件頁數(shù)： | 7/16頁 |
| 文件大小： | 615K |
| 代理商： | AD7846 |
AD7846
REV. E
–7–
V
DD
/V
SS
–
Volts
I
–
0.5
11
1.0
12
13
14
15
T
A
= +25 C
V
REF+
= +5V
V
= 0V
GAIN = +1
1.5
2.0
2.5
3.0
3.5
4.0
16
Figure 13. Typical Linearity vs. V
DD
/V
SS
V
DD
/V
SS
–
Volts
D
–
0
11
12
13
14
15
T
A
= +25 C
V
REF+
= +5V
V
= 0V
GAIN = +1
0.2
1.0
16
0.4
0.6
0.8
Figure 14. Typical Monotonicity vs.
V
DD
/V
SS
CIRCUIT DESCRIPTION
Digital Section
Figure 15 shows the digital control logic and on-chip data
latches in the AD7846. Table II is the associated truth table.
The D/A converter has two latches that are controlled by four
signals:
CS
, R/
W
,
LDAC
and
CLR
. The input latch is con-
nected to the data bus (DB15–DB0). A word is written to the
input latch by bringing
CS
low and R/
W
low. The contents of
the input latch may be read back by bringing
CS
low and R/
W
high. This feature is called “readback” and is used in system
diagnostic and calibration routines.
Data is transferred from the input latch to the DAC latch with
the
LDAC
strobe. The equivalent analog value of the DAC
latch contents appears at the DAC output. The
CLR
pin resets
the DAC latch contents to 000 . . . 000 or 100 . . . 000, depend-
ing on the state of R/
W
. Writing a
CLR
loads 000 . . . 000 and
reading a
CLR
loads 100 . . . 000. To reset a DAC to 0 V in a
unipolar system the user should exercise
CLR
while R/
W
is low;
to reset to 0 V in a bipolar system exercise the
CLR
while R/
W
is high.
R/
W
CLR
CS
DB15
DB0
16
16
16
DAC
DB15 RST
DB15 SET
DB14
–
DB0
RST
3-STATE I/O
LATCH
DB15
–
DB0
LATCHES
LDAC
Figure 15. Input Control Logic
Table II. Control Logic Truth Table
CS
R/
W
LDAC CLR
Function
1
X
X
X
3-State DAC I/O Latch in High-
Z State
DAC I/O Latch Loaded with
DB15–DB0
Contents of DAC I/O Latch
Available on DB15–DB0
Contents of DAC I/O Latch
Transferred to DAC Latch
DAC Latch Loaded with
000 . . . 000
DAC Latch Loaded with
100 . . . 000
0
0
X
X
0
1
X
X
X
X
0
1
X
0
X
0
X
1
X
0
D/A Conversion
Figure 16 shows the D/A section of the AD7846. There are
three DACs, each of which have their own buffer amplifiers.
DAC1 and DAC2 are 4-bit DACs. They share a 16-resistor
string but have their own analog multiplexers. The voltage refer-
ence is applied to the resistor string. DAC3 is a 12-bit voltage
mode DAC with its own output stage.
The 4 MSBs of the 16-bit digital code drive DAC1 and DAC2
while the 12 LSBs control DAC3. Using DAC1 and DAC2, the
MSBs select a pair of adjacent nodes on the resistor string and
present that voltage to the positive and negative inputs of
DAC3. This DAC interpolates between these two voltages to
produce the analog output voltage.
To prevent nonmonotonicity in the DAC due to amplifier offset
voltages, DAC1 and DAC2 “l(fā)eap-frog” along the resistor string.
For example, when switching from Segment 1 to Segment 2,
DAC1 switches from the bottom of Segment 1 to the top of
Segment 2 while DAC2 stays connected to the top of Segment
1. The code driving DAC3 is automatically complemented to
compensate for the inversion of its inputs. This means that any
linearity effects due to amplifier offset voltages remain un-
changed when switching from one segment to the next and
16-bit monotonicity is ensured if DAC3 is monotonic. So,
12-bit resistor matching in DAC3 guarantees overall 16-bit
monotonicity. This is much more achievable than the 16-bit
matching which a conventional R-2R structure would have
needed.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD7846_10 | 制造商:AD 制造商全稱:Analog Devices 功能描述:LC2MOS 16-Bit Voltage Output DAC |
| AD7846ACHIPS | 制造商:AD 制造商全稱:Analog Devices 功能描述:LC2MOS 16-Bit Voltage Output DAC |
| AD7846AP | 功能描述:IC DAC 16BIT LC2MOS VOUT 28PLCC RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 數(shù)模轉(zhuǎn)換器 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:1,000 系列:- 設(shè)置時間:1µs 位數(shù):8 數(shù)據(jù)接口:串行 轉(zhuǎn)換器數(shù)目:8 電壓電源:雙 ± 功率耗散（最大）:941mW 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:24-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:24-SOIC W 包裝:帶卷 (TR) 輸出數(shù)目和類型:8 電壓，單極 采樣率（每秒）:* |
| AD7846APZ | 功能描述:IC DAC 16BIT LC2MOS VOUT 28-PLCC RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 數(shù)模轉(zhuǎn)換器 系列:- 產(chǎn)品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:1,000 系列:- 設(shè)置時間:1µs 位數(shù):8 數(shù)據(jù)接口:串行 轉(zhuǎn)換器數(shù)目:8 電壓電源:雙 ± 功率耗散（最大）:941mW 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:24-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:24-SOIC W 包裝:帶卷 (TR) 輸出數(shù)目和類型:8 電壓，單極 采樣率（每秒）:* |
| AD7846AQ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述:IC,D/A CONVERTER,SINGLE,16-BIT,BICMOS,DIP,28PIN |
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