參數(shù)資料
型號： ADS7945SRTER
廠商： TEXAS INSTRUMENTS INC
元件分類： ADC
英文描述： 2-CH 14-BIT SUCCESSIVE APPROXIMATION ADC, SERIAL ACCESS, PQCC16
封裝： GREEN, PLASTIC, QFN-16
文件頁數(shù)： 28/49頁
文件大小： 1322K
代理商： ADS7945SRTER
+
–
RSOURCE
RS
CBYPASS
AVDD
GND
ADS7945
AINxP
AINxN
+
Signal Source
GND
SBAS539B
– JUNE 2011 – REVISED SEPTEMBER 2011
DRIVING AN ADC WITHOUT A DRIVING OP AMP
For some low input signal bandwidth applications, such as battery power monitoring or mains monitoring, it is not
required to operate an ADC at high sampling rates. In fact, it is desirable to avoid using a driving op amp from a
cost perspective. In these cases, the ADC input sees the impedance of the signal source (such as a battery or
mains transformer). This section elaborates the effects of source impedance on sampling frequency.
Equation 1 can be rewritten as Equation 4:
Sampling Time = Filter Time Constant
× Settling Resolution × ln(2)
(4)
As shown in Figure 87, it is recommended to use a bypass capacitor across the positive and negative ADC input
terminals.
Figure 87. Driving an ADS7945 ADC Without a Driving Op Amp
Source impedance (2
× RSOURCE + 2 × RS) with (CBYPASS + CSAMPLE) acts as a low-pass filter with Equation 5:
Filter Time Constant = 2
× (RSOURCE + RS) × (CBYPASS + CSAMPLE)
where:
CSAMPLE is the internal sampling capacitance of the ADC (equal to 32 pF).
(5)
34
Copyright
2011, Texas Instruments Incorporated
Product Folder Link(s): ADS7945 ADS7946
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相關代理商/技術參數(shù)
參數(shù)描述
ADS7945SRTET 功能描述:模數(shù)轉換器 - ADC 14B,2MSPS,DUAL-CH, UNIPOLAR,DIF,SAR ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結構:Sigma-Delta 轉換速率: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 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-32
ADS7946 制造商:TI 制造商全稱:Texas Instruments 功能描述:14-Bit, 2 MSPS, Dual-Channel, Differential/Single-Ended, Ultralow-Power Analog-to-Digital Converters
ADS7946EVM-PDK 功能描述:數(shù)據(jù)轉換 IC 開發(fā)工具 ADS7946 PERF DEM KIT RoHS:否 制造商:Texas Instruments 產(chǎn)品:Demonstration Kits 類型:ADC 工具用于評估:ADS130E08 接口類型:SPI 工作電源電壓:- 6 V to + 6 V
ADS7946SRTER 功能描述:模數(shù)轉換器 - ADC 14B,2MSPS,DUAL-CH, UNIP,PSE-DIF,SAR ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結構:Sigma-Delta 轉換速率: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 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-32
ADS7946SRTET 功能描述:模數(shù)轉換器 - ADC 14B,2MSPS,DUAL-CH, UNIP,PSE-DIF,SAR ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結構:Sigma-Delta 轉換速率: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 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-32
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