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參數(shù)資料
| 型號(hào)： | ADS809 |
| 英文描述： | 12-Bit, 80MHz Sampling ANALOG-TO-DIGITAL CONVERTER |
| 中文描述： | 12位，80MHz的采樣模擬數(shù)字轉(zhuǎn)換器 |
| 文件頁(yè)數(shù)： | 13/20頁(yè) |
| 文件大小： | 437K |
| 代理商： | ADS809 |
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ADS809
SBAS170C
13
www.ti.com
Figure 7 shows the basic model of the internal reference
circuit. The functional blocks are a 1V bandgap voltage
reference, a selectable gain amplifier, the drivers for the top
and bottom reference (REFT, REFB), and the resistive refer-
ence ladder. The ladder resistance measures approximately
660
between the REFT and REFB pin. The ladder is split
into two equal segments, establishing a common-mode volt-
age at the ladder midpoint, labeled
“
CM.
”
The ADS809
requires solid bypassing for all reference pins to keep the
effect of clock feedthrough to a minimum and to achieve the
specified level of performance. Figure 7 also demonstrates
the recommended decoupling scheme. All 0.1
μ
F capacitors
should be located as close to the pins as possible.
When operating the ADS809 from the internal reference, the
effective full-scale input span for each of the inputs, IN and
IN
, is determined by the voltages at REFT and REFB pins,
given as:
Input Span (differential) = 2x (REFT
–
REFB), in Vp-p = 2
V
REF
The top and bottom reference outputs may be used to
provide up to 1mA (sink or source) of current to external
circuits. Degradation of the differential linearity (DNL) and,
consequently, of the dynamic performance of the ADS809
may occur if this limit is exceeded.
Using External References
For even more design flexibility, the ADS809 can be oper-
ated with an external reference.
The utilization of an external reference voltage may be
considered for applications requiring higher accuracy, im-
proved temperature stability, or a continuous adjustment of
the converter
’
s full-scale range. Especially in multichannel
applications, the use of a common external reference offers
the benefit of improving the gain matching between convert-
ers. Selection between internal or external reference opera-
tion is controlled through the V
REF
pin. The internal reference
will become disabled if the voltage applied to the V
REF
pin
exceeds +3.5V
DC
. Once selected, the ADS809 requires two
reference voltages
—
a top-reference voltage applied to the
REFT pin and a bottom-reference voltage applied to the
REFB pin (see Table I). As illustrated in Figure 8, a micropower
reference (REF1004) and a dual, single-supply amplifier may
be used to generate a precision external reference. Note that
the function of the range select pins, SEL1 and SEL2, are
disabled while the converter is in external mode.
Range Select
and
Gain Amplifier
Top
Reference
Driver
Bottom
Reference
Driver
+1V
Bandgap
Reference
ADS809
REFT
CM
REFB
0.1
μ
F
1
μ
F
0.1
μ
F
0.1
μ
F
0.1
μ
F
0.1
μ
F
0.1
μ
F
ByP
SEL1 SEL2
PD
V
REF
330
330
1
FIGURE 7. Internal Reference Circuit of the ADS809 and Recommended Bypass Scheme.
R
3
R
4
R
1
R
2
+
+
2.2
μ
F
0.1
μ
F
0.1
μ
F
+
2.2
μ
F
0.1
μ
F
10
μ
F
REFT
REFB
ADS809
1/2
OPA2234
1/2
OPA2234
4.7k
+5V
–
5V
REF1004
+2.5V
FIGURE 8. Example for an External Reference Circuit Using a Dual, Single-Supply Op Amp.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADS809Y/250 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 80MHz Sampling ADC 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 |
| ADS809Y/250G4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 80MHz Sampling ADC 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 |
| ADS809Y/2K | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 80MHz Sampling ADC 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 |
| ADS809Y/2K5 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:A/D CONVERTER |
| ADS809Y/2KG4 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 80MHz Sampling ADC 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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