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參數(shù)資料
| 型號： | AD7840JNZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 4/16頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC DAC 14BIT LC2MOS LP 24-DIP |
| 產(chǎn)品培訓模塊： | Data Converter Fundamentals DAC Architectures |
| 標準包裝： | 15 |
| 設置時間： | 2.5µs |
| 位數(shù)： | 14 |
| 數(shù)據(jù)接口： | 串行，并聯(lián) |
| 轉(zhuǎn)換器數(shù)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： | 通孔 |
| 封裝/外殼： | 24-DIP（0.300"，7.62mm） |
| 供應商設備封裝： | 24-PDIP |
| 包裝： | 管件 |
| 輸出數(shù)目和類型： | 1 電壓，雙極 |
| 采樣率（每秒）： | 400k |
| 產(chǎn)品目錄頁面： | 785 (CN2011-ZH PDF) |
AD7840
REV. B
–12–
AD7840–TMS32020 Serial Interface
Figure 22 shows a serial interface between the AD7840 and the
TMS32020 DSP processor. In this interface, the CLKX and
FSX pin of the TMS32020 are generated from the clock/timer
circuitry. The same clock/timer circuitry generates the LDAC
signal of the AD7840 to synchronize the update of the output
with the serial transmission. The FSX pin of the TMS32020
must be configured as an input.
Data from the TMS32020 is valid on the falling edge of CLKX.
Once again, the FORMAT pin of the AD7840 must be tied to
+5 V while the JUSTIFY pin must be tied to DGND.
Figure 22. AD7840–TMS32020 Serial Interface
AD7840–NEC7720 Serial Interface
A serial interface between the AD7840 and the NEC7720 is
shown in Figure 23. The serial clock must be inverted before
being applied to the AD7840 SCLK input because data from
the processor is valid on the rising edge of SCK.
The NEC7720 is programmed for the LSB to be the first bit in
the serial data stream. Therefore, the AD7840 is set up with the
FORMAT pin tied to DGND and the JUSTIFY pin tied to +5 V.
Figure 23. AD7840–NEC7720 Serial Interface
APPLYING THE AD7840
Good printed circuit board layout is as important as the overall
circuit design itself in achieving high speed converter perfor-
mance. The AD7840 works on an LSB size of 366
V. There-
fore, the designer must be conscious of minimizing noise in both
the converter itself and in the surrounding circuitry. Switching
mode power supplies are not recommended as the switching
spikes can feed through to the on-chip amplifier. Other causes
of concern are ground loops and digital feedthrough from mi-
croprocessors. These are factors which influence any high per-
formance converter, and a proper PCB layout which minimizes
these effects is essential for best performance.
LAYOUT HINTS
Ensure that the layout for the printed circuit board has the digi-
tal and analog lines separated as much as possible. Take care
not to run any digital track alongside an analog signal track. Es-
tablish a single point analog ground (star ground) separate from
the logic system ground. Place this star ground as close as pos-
sible to the AD7840 as shown in Figure 24. Connect all analog
grounds to this star ground and also connect the AD7840
DGND pin to this ground. Do not connect any other digital
grounds to this analog ground point.
Figure 24. Power Supply Grounding Practice
Low impedance analog and digital power supply common re-
turns are essential to low noise operation of high performance
converters. Therefore, the foil width for these tracks should be
kept as wide as possible. The use of ground planes minimizes
impedance paths and also guards the analog circuitry from digi-
tal noise. The circuit layouts of Figures 27 and 28 have both
analog and digital ground planes which are kept separated and
only joined at the star ground close to the AD7840.
NOISE
Keep the signal leads on the VOUT signal and the signal return
leads to AGND as short as possible to minimize noise coupling.
In applications where this is not possible, use a shielded cable
between the DAC output and its destination. Reduce the
ground circuit impedance as much as possible since any poten-
tial difference in grounds between the DAC and its destination
device appears as an error voltage in series with the DAC output.
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| AD7840JNZ | 制造商:Analog Devices 功能描述:IC 14-BIT DAC |
| AD7840JP | 功能描述:IC DAC 14BIT 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:Data Converter Fundamentals DAC Architectures 標準包裝:750 系列:- 設置時間:7µs 位數(shù):16 數(shù)據(jù)接口:并聯(lián) 轉(zhuǎn)換器數(shù)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(shù)目和類型:1 電壓，單極；1 電壓，雙極 采樣率（每秒）:143k |
| AD7840JP-REEL | 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述: |
| AD7840JPZ | 功能描述:IC DAC 14BIT LC2MOS VOUT 28PLCC RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 數(shù)模轉(zhuǎn)換器 系列:- 標準包裝:1 系列:- 設置時間:4.5µs 位數(shù):12 數(shù)據(jù)接口:串行，SPI? 轉(zhuǎn)換器數(shù)目:1 電壓電源:單電源 功率耗散（最大）:- 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應商設備封裝:8-SOICN 包裝:剪切帶 (CT) 輸出數(shù)目和類型:1 電壓，單極；1 電壓，雙極 采樣率（每秒）:* 其它名稱:MCP4921T-E/SNCTMCP4921T-E/SNRCTMCP4921T-E/SNRCT-ND |
| AD7840JPZ-REEL | 功能描述:IC DAC 14BIT LC2MOS 28PLCC 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:Data Converter Fundamentals DAC Architectures 標準包裝:750 系列:- 設置時間:7µs 位數(shù):16 數(shù)據(jù)接口:并聯(lián) 轉(zhuǎn)換器數(shù)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(shù)目和類型:1 電壓，單極；1 電壓，雙極 采樣率（每秒）:143k |
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