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參數(shù)資料
| 型號： | ADS901 |
| 英文描述： | 10-Bit, 20MHz, #V Supply ANALOG-TO-DIGITAL CONVERTER |
| 文件頁數(shù)： | 10/11頁 |
| 文件大?。?/td> | 174K |
| 代理商： | ADS901 |
10
ADS901
1k
1k
LpBy
+2V
+1V
REFT
REFB
LnBy
+V
S
IN
CM
R
T
4k
1k
R
B
4k
1k
0.1μF
0.1μF
0.1μF
0.1μF
0.1μF
+3V
V
IN
ADS901
0.1μF
1k
0.1μF
10μF
LOW-COST REFERENCE SOLUTION
The easiest way to achieve the required reference voltages is
to place the reference ladder of the ADS901 between the
supply rails, as shown in Figure 5. Two additional resistors
(R
T
, R
B
) are necessary to set the correct current through the
ladder. However depending on the desired full-scale swing
and supply voltage different resistor values might be se-
lected.
The trade-offs, when selecting this reference circuit, are
variations in the reference voltages due to component toler-
ances and power supply variations. In any case, it is recom-
mended to bypass the reference ladder with at least 0.1
μ
F
ceramic capacitors, as shown in Figure 5. The capacitors
serve a dual purpose. They will bypass most of the high
frequency transient noise which results from feedthrough of
the clock and switching noise from the T/H stages. Sec-
ondly, they serve as a charge reservoir to supply instanta-
neous current to internal nodes.
FIGURE 5. Low Cost Solution to Supply External Reference Voltages and Recommended Reference Bypassing.
PRECISE REFERENCE SOLUTION
For those applications requiring a higher level of dc accu-
racy and drift, a reference circuit with a precision reference
element might be used (see Figure 6). A stable +1.2V
reference voltage is established by a two terminal bandgap
reference diode, the REF1004-1.2. Using a general-purpose
single-supply dual operational amplifier (A1), like an
OPA2237, OPA2234 or OPA2343, the two required refer-
ence voltages for the ADS901 can be generated by setting
each op amp to the appropriate gain; for example: set REFT
to +2V and REFB to +1V.
CLOCK INPUT
The clock input of the ADS901 is designed to accommodate
either +5V or +3V CMOS logic levels. To drive the clock
input with a minimum amount of duty cycle variation and
support maximum sampling rates (20Msps), high speed or
advanced CMOS logic should be used (HC/HCT, AC/ACT).
When digitizing at high sampling rates, a 50% duty cycle
clock with fast rise and fall times (2ns or less) are recom-
mended to meet the rated performance specifications. How-
ever, the ADS901 performance is tolerant to duty cycle
variations of as much as
±
10% without degradation. For
applications operating with input frequencies up to Nyquist
or undersampling applications, special consideration must
be made to provide a clock with very low jitter. Clock jitter
leads to aperture jitter (t
A
) which can be the ultimate limita-
tion to achieving good SNR performance. Equation (5)
shows the relationship between aperture jitter, input fre-
quency and the signal-to-noise ratio:
SNR = 20log
10
[1/(2
π
f
IN
t
A
)]
For example, with a 10MHz full-scale input signal and an
aperture jitter of t
A
= 20ps, the SNR is clock jitter limited to
58dB.
(5)
+FS (IN = +2V)
+FS –1LSB
+FS –2LSB
+3/4 Full Scale
+1/2 Full Scale
+1/4 Full Scale
+1LSB
Bipolar Zero (IN +1.5V)
–1LSB
–1/4 Full Scale
–1/2 Full Scale
–3/4 Full Scale
–FS +1LSB
–FS (IN = +1V)
1111111111
1111111111
1111111110
1110000000
1100000000
1010000000
1000000001
1000000000
0111111111
0110000000
0100000000
0010000000
0000000001
0000000000
STRAIGHT OFFSET BINARY
(SOB)
PIN 12
FLOATING or LO
SINGLE-ENDED INPUT
TABLE I. Coding Table for the ADS901.
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PDF描述 |
|---|---|
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| ADS902E | 10-Bit, 30MHz Sampling ANALOG-TO-DIGITAL CONVERTER |
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| ADS901E | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 10-Bit 20 MSPS SE/Diff 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 |
| ADS901E | 制造商:Texas Instruments 功能描述:Analog-Digital Converter IC Number of Bi |
| ADS901E/1K | 功能描述:視頻模擬/數(shù)字化轉(zhuǎn)換器集成電路 10-Bit 20 MSPS SE/Diff Input RoHS:否 制造商:Texas Instruments 輸入信號類型:Differential 轉(zhuǎn)換器數(shù)量:1 ADC 輸入端數(shù)量:4 轉(zhuǎn)換速率:3 Gbps 分辨率:8 bit 結(jié)構(gòu): 輸入電壓:3.3 V 接口類型:SPI 信噪比: 電壓參考: 電源電壓-最大:3.45 V 電源電壓-最小:3.15 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:TCSP-48 封裝:Reel |
| ADS901E/1KG4 | 功能描述:視頻模擬/數(shù)字化轉(zhuǎn)換器集成電路 10-Bit 20 MSPS SE/Diff Input RoHS:否 制造商:Texas Instruments 輸入信號類型:Differential 轉(zhuǎn)換器數(shù)量:1 ADC 輸入端數(shù)量:4 轉(zhuǎn)換速率:3 Gbps 分辨率:8 bit 結(jié)構(gòu): 輸入電壓:3.3 V 接口類型:SPI 信噪比: 電壓參考: 電源電壓-最大:3.45 V 電源電壓-最小:3.15 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:TCSP-48 封裝:Reel |
| ADS901EG4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 10-Bit 20 MSPS SE/Diff 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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