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參數(shù)資料
| 型號： | ADS930E |
| 英文描述： | 8-Bit, 30MHz Sampling ANALOG-TO-DIGITAL CONVERTER |
| 中文描述： | 8位，30MHz的采樣模擬數(shù)字轉(zhuǎn)換器 |
| 文件頁數(shù)： | 10/11頁 |
| 文件大?。?/td> | 191K |
| 代理商： | ADS930E |
10
ADS930
DC-COUPLED INTERFACE CIRCUIT
Figure 5 illustrates an example of a DC-coupled interface
circuit using one high-speed op amp to level-shift the ground-
referenced input signal. This serves to condition it for the
input requirements of the ADS930. With a +3V supply the
input signal swings 1Vp-p centered around a typical com-
mon-mode voltage of +1.5V. This voltage can be derived
from the internal bottom reference (REFB) and then fed
back through a resistor divider (R
1
, R
2
) to level-shift the
driving op amp (A
1
). A capacitor across R
2
will shunt most
of the wideband noise to ground. Depending on the config-
ured gain, the values of resistors R
1
and R
2
must be adjusted
since the offsetting voltage (V
OS
) is amplified by the non-
inverting gain, 1 + (R
F
/R
IN
). This example assumes the sum
of R
1
and R
2
to be 5k
, drawing only 250
μ
A from the
bottom reference. Considerations for the selection of a
proper op amp should include its output swing, input com-
mon-mode range, and bias current. This circuit can easily be
modified for a +5V operation of the A/D converter, requir-
ing a higher common-mode level (+2.5V).
INTERNAL REFERENCE
The ADS930 features an internal reference that provides
fixed reference voltages for the internal stages. As shown in
Figure 6, each end of the resistor ladder (REFT and REFB)
are driven by a buffer amplifier. The ladder has a nominal
resistance of 4k
(
±
15%). The two outputs of the buffers are
brought out at pin 21 (LpBy) and pin 25 (LnBy), primarily
to connect external bypass capacitors, typically 0.1
μ
F. They
will shunt the high frequency switching noise that is fed
back into the reference circuit and improve the performance.
The buffers can drive limited external loads, for example
level-shifting of the converter’s interface circuit. However,
the current draw should be limited to approximately 1mA.
Derived from the top reference of +1.75V is an additional
voltage of +1.0V. Note that this voltage, available on pin 23,
is not buffered and care should be taken when external loads
are applied. In normal operation, this pin is left unconnected
and no bypassing components are required.
CLOCK INPUT
The clock input of the ADS930 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 the maximum sampling rate (30MSPS), high speed
or advanced CMOS logic should be used (HC/HCT, AC/
ACT). When digitizing at high sampling rates, a 50% duty
cycle, along with fast rise and fall times (2ns or less), are
FIGURE 6. Internal Reference Structure and Recommended Reference Bypassing.
ADS930
2.8k
2k
2k
+1.75V
+1.25V
2.1k
0.1μF
REFT
REFB
LpBy
21
23
26
25
+1V
REF
0.1μF
LnBy
0.1μF
CM
FIGURE 5. Single-supply, DC-coupled Interface Circuit.
OPA680
V
IN
+5V
R
F
V
CM
= 1.5V
I = 250μA
0.1μF
IN
CM
REFB
+1.25V
R
S
R
IN
+3V
R
1
R
2
V
OS
0.1μF
22pF
0.1μF
ADS930
IN
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADS930E | 制造商:Texas Instruments 功能描述:IC's |
| ADS930E/1K | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 8-Bit 30 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 |
| ADS930E/1KG4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 8-Bit 30 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 |
| ADS930EG4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 8-Bit 30 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 |
| ADS-930MC | 制造商:Murata Power Solutions 功能描述:Single ADC Pipelined 500ksps 16-bit Parallel 40-Pin TDIP |
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