參數(shù)資料
型號(hào)： ADS8481IBRGZRG4
英文描述： 18-BIT, 1-MSPS, PSEUDO-DIFFERENTIAL UNIPOLAR INPUT, MICROPOWER SAMPLING ANALOG-TO-DIGITAL CONVERTER WITH PARALLEL INTERFACE AND REFERENCE
中文描述： 18位，1 MSPS的，偽差分單極輸入，微采樣模擬到數(shù)字轉(zhuǎn)換并行接口和參考
文件頁(yè)數(shù)： 24/31頁(yè)
文件大?。?/td> 717K
代理商： ADS8481IBRGZRG4
www.ti.com
LAYOUT
For optimum performance, care must be taken with the physical layout of the ADS8481 circuitry.
ADS8481
SLAS385A–FEBRUARY 2006–REVISED MARCH 2006
As the ADS8481 offers single-supply operation, it is often used in close proximity with digital logic,
microcontrollers, microprocessors, and digital signal processors. The more digital logic present in the design and
the higher the switching speed, the more difficult it is to achieve good performance from the converter.
The basic SAR architecture is sensitive to glitches or sudden changes on the power supply, reference, ground
connections and digital inputs that occur just prior to latching the output of the analog comparator. Thus, driving
any single conversion for an n-bit SAR converter, there are at least n windows in which large external transient
voltages can affect the conversion result. Such glitches might originate from switching power supplies, nearby
digital logic, or high power devices.
The degree of error in the digital output depends on the reference voltage, layout, and the exact timing of the
external event.
On average, the ADS8481 draws very little current from an external reference as the reference voltage is
internally buffered. If the reference voltage is external and originates from an op amp, make sure that it can drive
the bypass capacitor or capacitors without oscillation. A 0.1-
μ
F capacitor is recommended from pin 13 (REFIN)
directly to pin 12 (REFM). REFM and AGND must be shorted on the same ground plane under the device.
The AGND and BDGND pins should be connected to a clean ground point. In all cases, this should be the
analog ground. Avoid connections which are too close to the grounding point of a microcontroller or digital signal
processor. If required, run a ground trace directly from the converter to the power supply entry point. The ideal
layout consists of an analog ground plane dedicated to the converter and associated analog circuitry.
As with the AGND connections, +VA should be connected to a 5-V power supply plane or trace that is separate
from the connection for digital logic until they are connected at the power entry point. Power to the ADS8481
should be clean and well bypassed. A 0.1-
μ
F ceramic bypass capacitor should be placed as close to the device
as possible. See
Table 3
for the placement of the capacitor. In addition, a 1-
μ
F to 10-
μ
F capacitor is
recommended. In some situations, additional bypassing may be required, such as a 100-
μ
F electrolytic capacitor
or even a Pi filter made up of inductors and capacitors—all designed to essentially low-pass filter the 5-V supply,
removing the high frequency noise.
Table 3. Power Supply Decoupling Capacitor Placement
POWER SUPPLY PLANE
SUPPLY PINS
CONVERTER
DIGITAL SIDE
CONVERTER ANALOG SIDE
Pin pairs that require shortest path to decoupling capacitors
Pins that require no decoupling
(7,8), (9,10), (16,17), (20,21), (22,23), (25,26)
24, 26
36, 37
1
24
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相關(guān)PDF資料
PDF描述
ADS8481IBRGZT 18-BIT, 1-MSPS, PSEUDO-DIFFERENTIAL UNIPOLAR INPUT, MICROPOWER SAMPLING ANALOG-TO-DIGITAL CONVERTER WITH PARALLEL INTERFACE AND REFERENCE
ADS8481IBRGZTG4 18-BIT, 1-MSPS, PSEUDO-DIFFERENTIAL UNIPOLAR INPUT, MICROPOWER SAMPLING ANALOG-TO-DIGITAL CONVERTER WITH PARALLEL INTERFACE AND REFERENCE
ADS8481IPFBR 18-BIT, 1-MSPS, PSEUDO-DIFFERENTIAL UNIPOLAR INPUT, MICROPOWER SAMPLING ANALOG-TO-DIGITAL CONVERTER WITH PARALLEL INTERFACE AND REFERENCE
ADS8481IPFBT 18-BIT, 1-MSPS, PSEUDO-DIFFERENTIAL UNIPOLAR INPUT, MICROPOWER SAMPLING ANALOG-TO-DIGITAL CONVERTER WITH PARALLEL INTERFACE AND REFERENCE
ADS8481IRGZR 18-BIT, 1-MSPS, PSEUDO-DIFFERENTIAL UNIPOLAR INPUT, MICROPOWER SAMPLING ANALOG-TO-DIGITAL CONVERTER WITH PARALLEL INTERFACE AND REFERENCE
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ADS8481IBRGZT 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 18-Bit 1-MSPS Pseudo Diff Unipolar Input 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(lèi)型:Differential 信噪比:107 dB 接口類(lèi)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
ADS8481IBRGZTG4 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 18-Bit 1-MSPS Pseudo Diff Unipolar Input 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(lèi)型:Differential 信噪比:107 dB 接口類(lèi)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
ADS8481IPFBR 制造商:BB 制造商全稱(chēng):BB 功能描述:18-BIT, 1-MSPS, PSEUDO-DIFFERENTIAL UNIPOLAR INPUT, MICROPOWER SAMPLING ANALOG-TO-DIGITAL CONVERTER WITH PARALLEL INTERFACE AND REFERENCE
ADS8481IPFBT 制造商:BB 制造商全稱(chēng):BB 功能描述:18-BIT, 1-MSPS, PSEUDO-DIFFERENTIAL UNIPOLAR INPUT, MICROPOWER SAMPLING ANALOG-TO-DIGITAL CONVERTER WITH PARALLEL INTERFACE AND REFERENCE
ADS8481IRGZR 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 18-Bit 1MSPS Parall ADC w/Ref 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(lèi)型:Differential 信噪比:107 dB 接口類(lèi)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
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