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參數(shù)資料
| 型號(hào)： | ADS7820P |
| 英文描述： | 12-Bit 10ms Sampling CMOS ANALOG-to-DIGITAL CONVERTER |
| 中文描述： | 12位10ms的采樣CMOS模擬數(shù)字轉(zhuǎn)換器 |
| 文件頁數(shù)： | 10/10頁 |
| 文件大?。?/td> | 280K |
| 代理商： | ADS7820P |
10
ADS7820
LAYOUT
POWER
For optimum performance, tie the analog and digital power
pins to the same +5V power supply and tie the analog and
digital grounds together. As noted in the electrical specifica-
tions, the ADS7820 uses 90% of its power for the analog
circuitry. The ADS7820 should be considered as an analog
component.
The +5V power for the A/D should be separate from the +5V
used for the system’s digital logic. Connecting V
DIG
(pin 28)
directly to a digital supply can reduce converter performance
due to switching noise from the digital logic. For best
performance, the +5V supply can be produced from what-
ever analog supply is used for the rest of the analog signal
conditioning. If +12V or +15V supplies are present, a simple
+5V regulator can be used. Although it is not suggested, if
the digital supply must be used to power the converter, be
sure to properly filter the supply. Either using a filtered
digital supply or a regulated analog supply, both V
DIG
and
V
ANA
should be tied to the same +5V source.
GROUNDING
Three ground pins are present on the ADS7820. DGND is
the digital supply ground. AGND2 is the analog supply
ground. AGND1 is the ground which all analog signals
internal to the A/D are referenced. AGND1 is more suscep-
tible to current induced voltage drops and must have the path
of least resistance back to the power supply.
All the ground pins of the A/D should be tied to the analog
ground plane, separated from the system’s digital logic
ground, to achieve optimum performance. Both analog and
digital ground planes should be tied to the “system” ground
as near to the power supplies as possible. This helps to
prevent dynamic digital ground currents from modulating
the analog ground through a common impedance to power
ground.
SIGNAL CONDITIONING
The FET switches used for the sample hold on many CMOS
A/D converters release a significant amount of charge injec-
tion which can cause the driving op amp to oscillate. The
FET switch on the ADS7820, compared to the FET switches
on other CMOS A/D converters, releases 5%-10% of the
charge. There is also a resistive front end which attenuates
any charge which is released. The end result is a minimal
requirement for the anti-alias filter on the front end. Any op
amp sufficient for the signal in an application will be
sufficient to drive the ADS7820.
INTERMEDIATE LATCHES
The ADS7820 does have tri-state outputs for the parallel
port, but intermediate latches should be used if the bus will
be active during conversions. If the bus is not active during
conversion, the tri-state outputs can be used to isolate the
A/D from other peripherals on the same bus. Tri-state
outputs can also be used when the A/D is the only peripheral
on the data bus.
Intermediate latches are beneficial on any monolithic A/D
converter. The ADS7820 has an internal LSB size of 610
μ
V.
Transients from fast switching signals on the parallel port,
even when the A/D is tri-stated, can be coupled through the
substrate to the analog circuitry causing degradation of
converter performance. The effects of this phenomenon will
be more obvious when using the pin-compatible ADS7821
or any of the other 16-bit converters in the ADS Family. This
is due to the smaller internal LSB size of 38
μ
V.
相關(guān)PDF資料 |
PDF描述 |
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| ADS7820PB | 12-Bit 10ms Sampling CMOS ANALOG-to-DIGITAL CONVERTER |
| ADS7820U | CMOS Dual 4-Input NOR Gate 14-SOIC -55 to 125 |
| ADS7820UB | 12-Bit 10ms Sampling CMOS ANALOG-to-DIGITAL CONVERTER |
| ADS7831 | 12-Bit 600kHz Sampling CMOS ANALOG-to-DIGITAL CONVERTER |
| ADS7831P | 12-Bit 600kHz Sampling CMOS ANALOG-to-DIGITAL CONVERTER |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADS7820PB | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12bit 10 Micro-Sec RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| ADS7820U | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| ADS7820UB | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| ADS7821 | 制造商:BB 制造商全稱:BB 功能描述:16-Bit 10ms Sampling CMOS ANALOG-to-DIGITAL CONVERTER |
| ADS7821P | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
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