參數(shù)資料
型號: ADS8482IBRGZT
英文描述: 18-BIT, 1-MSPS, PSEUDO-BIPOLAR, FULLY DIFFERENTIAL INPUT, MICROPOWER SAMPLING ANALOG-TO-DIGITAL CONVERTER WITH PARALLEL INTERFACE, REFERENCE
中文描述: 18位,1 MSPS的,偽雙極,全差分輸入,微采樣模擬到數(shù)字轉(zhuǎn)換并行接口,參考
文件頁數(shù): 25/31頁
文件大小: 647K
代理商: ADS8482IBRGZT
www.ti.com
RESET
On power-up, internal POWER-ON RESET circuitry generates the reset required for the device. The first three
conversions after power-up are used to load factory trimming data for a specific device to assure high accuracy
of the converter. The results of the first three conversions are invalid and should be discarded.
LAYOUT
For optimum performance, care must be taken with the physical layout of the ADS8482 circuitry.
ADS8482
SLAS386A–JULY 2005–REVISED JUNE 2006
Table 2. Conversion Data Read Out (continued)
DATA READ OUT
PINS
DB9–DB4
All One's
D9–D4
BYTE
BUS18/16
PINS
PINS
PINS
DB3–DB2
All One's
D3–D2
PINS
DB1–DB0
All One's
D1–D0
DB17–DB12
D9–D4
D17–D12
DB11–DB10
D3–D2
D11–D10
High
Low
Low
Low
The device can also be reset through the use of the combination fo CS and CONVST. Since the BUSY signal is
held at high during the conversion, either one of these conditions triggers an internal self-clear reset to the
converter.
Issue a CONVST when CS is low and the internal convert state is high. The falling edge of CONVST starts
a reset.
Issue a CS (select the device) while the internal convert state is high. The falling edge of CS causes a reset.
Once the device is reset, all output latches are cleared (set to zeroes) and the BUSY signal is brought low. A
new sampling period is started at the falling edge of the BUSY signal immediately after the instant of the internal
reset.
As the ADS8482 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 ADS8482 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 ADS8482
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.
25
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ADS8482IBRGZTG4 18-BIT, 1-MSPS, PSEUDO-BIPOLAR, FULLY DIFFERENTIAL INPUT, MICROPOWER SAMPLING ANALOG-TO-DIGITAL CONVERTER WITH PARALLEL INTERFACE, REFERENCE
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ADS8482IRGZR 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
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ADS8482IRGZT 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
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