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參數資料
| 型號： | AD7994 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | 4-Channel, 12-/10-Bit ADCs with I2C Compatible Interface in 16-Lead TSSOP |
| 中文描述： | 4通道，12-/10-Bit ADC的16 - I2C兼容接口的無鉛TSSOP封裝 |
| 文件頁數： | 14/27頁 |
| 文件大小： | 277K |
| 代理商： | AD7994 |
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AD7994/AD7993
–14–
REV. PrF
PRELIMINARY TECHNICAL DATA
Analog Input
Figure 6 shows an equivalent circuit of the analog input
sturcture of the AD7994/AD7993. The two diodes D1 and
D2 provide ESD protection for the analog inputs. Care
must be taken to ensure that the analog input signal never
exceeds the supply rails by more than 300mV. This will
cause these diodes to become forward biased and start
conducting current into the substrate. 10 mA is the maxi-
mum current these diodes can conduct without causing
irreversable damage to the part.
The capacitor C1 in Figure 6 is typically about 4pF and
can primarily be attributed to pin capacitance. The resis-
tor R1 is a lumped component made up of the on resis-
tance (R
ON
) of a switch(track and hold switch) and also
includes the R
ON
of the input multiplexer. The total resis-
tance is typically about 400
.
The capacitor C2 is the
ADC sampling capacitor and has a capacitance of 30 pF
typically.
For ac applications, removing high frequency components
from the analog input signal is recommended by use of an
RC band-pass filter on the relevant analog input pin. In
applications where harmonic distortion and signal to noise
ratio are critical the analog input should be driven from a
low impedance source. Large source impedances will sig-
nificantly affect the ac performance of the ADC. This may
necessitate the use of an input buffer amplifier. The choice
of the op amp will be a function of the particular applica-
tion.
When no amplifier is used to drive the analog input the
source impedance should be limited to low values. The
maximum source impedance will depend on the amount of
total harmonic distortion (THD) that can be tolerated.
The THD will increase as the source impedance increases
and performance will degrade. Figure 7 shows a graph of
the Total Harmonic Distortion vs. analog input signal
frequency for different source impedances when using a
supply voltage of 3V±10% and 5V±10% and sampling at
a rate of xkSPS. Figure 8 shows a graph of the total har-
monic distortion versus analog input signal frequency for
various supply voltages while sampling at xkSPS .
Figure 6. Equivalent Analog Input Circuit
Figure 7. THD vs. Analog Input Frequency for
Various Source Impedance for V
DD
= 3V and 5V
Figure 8. THD vs. Analog Input Frequency,
Fs = xkSPS
Figure 5 AD7994/AD7993 Typical Connection Diagram
VIN
D1
VDD
D2
R1
C2
16PF
C1
4PF
CONVERSION PHASE - SWITCH OPEN
TRACK PHASE - SWITCH CLOSED
V
DD
VIN1
VIN2
VIN3
VIN4
GND
+5V SUPPLY
REF 19X
0.1μF
0.1μF
10μF
AD7994/
AD7993
0V to REFIN
INPUT
SDA
μC/μP
SCL
TWO WIRE SERIAL
INTERFACE
ALERT
REFIN
R
P
R
P
R
P
SET TO REQUIRED
ADDRESS
AS
相關PDF資料 |
PDF描述 |
|---|---|
| AD7993BRU-1 | 4-Channel, 12-/10-Bit ADCs with I2C Compatible Interface in 16-Lead TSSOP |
| AD7997 | 8-Channel, 10- and 12-Bit ADCs with I2CCompatible |
| AD7997BRU-0 | 8-Channel, 10- and 12-Bit ADCs with I2CCompatible |
| AD7997BRU-0REEL | 8-Channel, 10- and 12-Bit ADCs with I2CCompatible |
| AD7997BRU-1 | 8-Channel, 10- and 12-Bit ADCs with I2CCompatible |
相關代理商/技術參數 |
參數描述 |
|---|---|
| AD7994-0 | 制造商:AD 制造商全稱:Analog Devices 功能描述:4-Channel, 10- and 12-Bit ADCs with I2C Compatible Interface in 16-Lead TSSOP |
| AD7994-1 | 制造商:AD 制造商全稱:Analog Devices 功能描述:4-Channel, 10- and 12-Bit ADCs with I2C Compatible Interface in 16-Lead TSSOP |
| AD7994BRU-0 | 功能描述:IC ADC 12BIT 4CHAN I2C 16TSSOP RoHS:否 類別:集成電路 (IC) >> 數據采集 - 模數轉換器 系列:- 標準包裝:1,000 系列:- 位數:16 采樣率（每秒）:45k 數據接口:串行 轉換器數目:2 功率耗散（最大）:315mW 電壓電源:模擬和數字 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:28-SOIC（0.295"，7.50mm 寬） 供應商設備封裝:28-SOIC W 包裝:帶卷 (TR) 輸入數目和類型:2 個單端，單極 |
| AD7994BRU-0REEL | 功能描述:IC ADC 12BIT 4CHAN I2C 16TSSOP RoHS:否 類別:集成電路 (IC) >> 數據采集 - 模數轉換器 系列:- 標準包裝:1,000 系列:- 位數:16 采樣率（每秒）:45k 數據接口:串行 轉換器數目:2 功率耗散（最大）:315mW 電壓電源:模擬和數字 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:28-SOIC（0.295"，7.50mm 寬） 供應商設備封裝:28-SOIC W 包裝:帶卷 (TR) 輸入數目和類型:2 個單端，單極 |
| AD7994BRU-1 | 制造商:Analog Devices 功能描述:ADC Single SAR 188ksps 12-bit Serial 16-Pin TSSOP 制造商:Rochester Electronics LLC 功能描述: |
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