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參數資料
| 型號： | AD7849 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Serial Input, 14-Bit/16-Bit DAC |
| 中文描述： | 串行輸入，14-Bit/16-Bit援 |
| 文件頁數： | 14/15頁 |
| 文件大小： | 211K |
| 代理商： | AD7849 |
REV. B
–
14
–
AD7849
APPLICATIONS
Opto-Isolated Interface
In many process control type applications it is necessary to
provide an isolation barrier between the controller and the unit
being controlled. Opto isolators can provide voltage isolation in
excess of 3 kV. The serial loading structure of the AD7849
makes it ideal for opto-isolated interfaces as the number of
interface lines is kept to a minimum.
Figure 25 shows a 4-channel isolated interface using the
AD7849. The DCEN pin must be connected high to enable the
daisy-chain facility. Four channels with 14-bit or 16-bit resolu-
tion are provided in the circuit shown, but this may be expanded
to accommodate any number of DAC channels without any
extra isolation circuitry. The only limitation is the output up-
date rate. For example, if an output update rate of 10 kHz is
required, then all the DACs must be loaded and updated in a
time period of 100
μ
s. Operating at the maximum clock rate of
5 MHz means that it takes 3.2
μ
s to load a DAC. This means
that the total number of channels for this update rate would be
31. This leaves 800 ns for the
LDAC
pulse. Of course, as the
update rate requirement decreases, the number of possible
channels increases.
The sequence of events to program the output channels in Fig-
ure 25 is as follows.
1. Take the
SYNC
line low.
2. Transmit the data as four 16-bit words. A total of 64 clock
pulses is required to clock the data through the chain.
3. Take the
SYNC
line high.
4. Pulse the
LDAC
line low. This updates all output channels
simultaneously on the falling edge of
LDAC
.
To reduce the number of opto-couplers, the
LDAC
line could
be driven from a one-shot which is triggered by the rising edge
on the
SYNC
line. A low level pulse of 100 ns duration or
greater is all that is required to update the outputs.
V
DD
DATA OUT
CLOCK OUT
SYNC OUT
CONTROL OUT
CONTROLLER
V
OUT
A
+5V
QUAD OPTO-COUPLER
*ADDITIONAL PINS OMITTED FOR CLARITY
V
DD
V
DD
V
DD
SCLK
SYNC
LDAC
SDIN
V
OUT
DCEN
SDOUT
AD7849*
V
OUT
B
+5V
SCLK
SYNC
LDAC
SDIN
V
OUT
DCEN
SDOUT
AD7849*
V
OUT
C
+5V
SCLK
SYNC
LDAC
SDIN
V
OUT
DCEN
SDOUT
AD7849*
V
OUT
D
+5V
SCLK
SYNC
LDAC
SDIN
V
OUT
DCEN
SDOUT
AD7849*
Figure 25. Four-Channel Opto-Isolated Interface
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PDF描述 |
|---|---|
| AD7849AN | Serial Input, 14-Bit/16-Bit DAC |
| AD7849AR | Serial Input, 14-Bit/16-Bit DAC |
| AD7849BN | Serial Input, 14-Bit/16-Bit DAC |
| AD7849BR | Serial Input, 14-Bit/16-Bit DAC |
| AD7849CN | Serial Input, 14-Bit/16-Bit DAC |
相關代理商/技術參數 |
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| AD7849AN | 制造商:Analog Devices 功能描述:DAC 1-CH R-2R 14-bit 20-Pin PDIP N Tube 制造商:Rochester Electronics LLC 功能描述:SERIAL INPUT,16-BIT DAC I.C. - Bulk |
| AD7849ANZ | 功能描述:IC DAC 16BIT SERIAL INP 20DIP RoHS:是 類別:集成電路 (IC) >> 數據采集 - 數模轉換器 系列:- 產品培訓模塊:Data Converter Fundamentals DAC Architectures 標準包裝:750 系列:- 設置時間:7µs 位數:16 數據接口:并聯 轉換器數目:1 電壓電源:雙 ± 功率耗散（最大）:100mW 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:28-LCC（J 形引線） 供應商設備封裝:28-PLCC（11.51x11.51） 包裝:帶卷 (TR) 輸出數目和類型:1 電壓，單極；1 電壓，雙極 采樣率（每秒）:143k |
| AD7849AR | 功能描述:IC DAC 16BIT SRL INP 20-SOIC RoHS:否 類別:集成電路 (IC) >> 數據采集 - 數模轉換器 系列:- 產品培訓模塊:Data Converter Fundamentals DAC Architectures 標準包裝:750 系列:- 設置時間:7µs 位數:16 數據接口:并聯 轉換器數目:1 電壓電源:雙 ± 功率耗散（最大）:100mW 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:28-LCC（J 形引線） 供應商設備封裝:28-PLCC（11.51x11.51） 包裝:帶卷 (TR) 輸出數目和類型:1 電壓，單極；1 電壓，雙極 采樣率（每秒）:143k |
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