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参数资料
| 型号： | AD9057PCB |
| 厂商： | Analog Devices, Inc. |
| 英文描述： | 8-Bit 40 MSPS/60 MSPS/80 MSPS A/D Converter |
| 中文描述： | 8位40 MSPS/60 MSPS/80 MSPS的A / D转换 |
| 文件页数： | 7/12页 |
| 文件大小： | 184K |
| 代理商： | AD9057PCB |
AD9057
–7–
REV. B
T HE ORY OF OPE RAT ION
T he AD9057 combines Analog Devices’ proprietary MagAmp
gray code conversion circuitry with flash converter technology to
provide a high performance, low cost ADC. T he design archi-
tecture ensures low power, high speed, and 8-bit accuracy. A
single-ended T T L/CMOS compatible ENCODE input controls
ADC timing for sampling the analog input pin and strobing the
digital outputs (D7–D0). An internal voltage reference (VREF
OUT ) may be used to control ADC gain and offset or an exter-
nal reference may be applied.
T he analog input signal is buffered at the input of the ADC and
applied to a high speed track-and-hold. T he T /H circuit holds
the analog input value during the conversion process (beginning
with the rising edge of the ENCODE command). T he T /H’s
output signal passes through the gray code and flash conversion
stages to generate coarse and fine digital representations of the
held analog input level. Decode logic combines the multistage
data and aligns the 8-bit word for strobed outputs on the rising
edge of the ENCODE command. T he MagAmp/Flash architec-
ture of the AD9057 results in three pipeline delays for the out-
put data.
USING T HE AD9057
Analog Inputs
T he AD9057 provides a single-ended analog input impedance of
150 k
. T he input requires a dc bias current of 6
μ
A (typical)
centered near +2.5 V (
±
10%). T he dc bias may be provided by
the user or may be derived from the ADC’s internal voltage
reference. Figure 14 shows a low cost dc bias implementation
allowing the user to capacitively couple ac signals directly into
the ADC without additional active circuitry. For best dynamic
performance, the VREF OUT pin should be decoupled to
ground with a 0.1
μ
F capacitor (to minimize modulation of
the reference voltage) and the bias resistor should be approxi-
mately 1 k
. A 1 k
bias resistor (
±
20%) is included within
the AD9057 and may be used to reduce application board size
and complexity.
2
3
7
AD9057
REF OUT
AIN
0.1μF
+5V
VIN
(1V p-p)
REF IN
BIAS OUT
1k
6
0.1μF
Figure 14. Capacitively Coupled AD9057
Figure 15 shows typical connections for high performance dc
biasing using the ADC’s internal voltage reference. All compo-
nents may be powered from a single +5 V supply (in the example
analog input signals are referenced to ground).
2
3
7
AD9057
REF OUT
REF IN
AIN
0.1μF
10k
10k
AD8041
+5V
1k
+5V
1k
VIN
(–0.5V TO +0.5V)
Figure 15. DC Coupled AD9057 (Inverted VIN)
Voltage Reference
A stable and accurate +2.5 V voltage reference is built into the
AD9057 (VREF OUT ). T he reference output may be used to
set the ADC gain/offset by connecting VREF OUT to VREF IN.
T he internal reference is capable of providing 300
μ
A of drive
current (for dc biasing the analog input or other user circuitry).
Some applications may require greater accuracy, improved
temperature performance, or gain adjustments which cannot be
obtained using the internal reference. An external voltage may
be applied to the VREF IN with VREF OUT disconnected for
gain adjustment of up to
±
10% (the VREF IN pin is internally
tied directly to the ADC circuitry). ADC gain and offset will
vary simultaneously with external reference adjustment with a
1:1 ratio (a 2% or 50 mV adjustment to the +2.5 V reference
varies ADC gain by 2% and ADC input range center offset by
50 mV). T heoretical input voltage range versus reference input
voltage may be calculated from the following equations:
V
RANGE
(p-p)
= VREF IN/
2.5
V
MIDSCALE
= VREF IN
V
TOP-OF-RANGE
= VREF IN + V
RANGE
/2
V
BOTTOM-OF-RANGE
= VREF IN – V
RANGE
/2
Digital Logic (+5 V/+3 V Systems)
T he digital inputs and outputs of the AD9057 can easily be
configured to interface directly with +3 V or +5 V logic systems.
T he ENCODE and power-down (PWRDN) inputs are CMOS
stages with T T L thresholds of 1.5 V, making the inputs compat-
ible with T T L, +5 V CMOS, and +3 V CMOS logic families.
As with all high speed data converters, the encode signal should
be clean and jitter free to prevent degradation of ADC dynamic
performance.
T he AD9057’s digital outputs will also interface directly with
+5 V or +3 V CMOS logic systems. T he voltage supply pin
(V
DD
) for these CMOS stages is isolated from the analog V
D
voltage supply. By varying the voltage on this supply pin the
digital output HIGH level will change for +5 V or +3 V systems.
Optimum SNR is obtained running the outputs at +3 V. Care
should be taken to isolate the V
DD
supply voltage from the +5 V
analog supply to minimize digital noise coupling into the ADC.
相关PDF资料 |
PDF描述 |
|---|---|
| AD9057-PCB | 8-Bit 40 MSPS/50 MSPS/80 MSPS Converter |
| AD9057-40 | Circular Connector; MIL SPEC:MIL-C-26482, Series I, Solder; Body Material:Aluminum; Series:PT06; Number of Contacts:19; Connector Shell Size:14; Connecting Termination:Solder; Circular Shell Style:Straight Plug; Body Style:Straight |
| AD9057-60 | Circular Connector; Body Material:Aluminum; Series:PT06; No. of Contacts:19; Connector Shell Size:14; Connecting Termination:Solder; Circular Shell Style:Straight Plug; Circular Contact Gender:Pin; Insert Arrangement:14-19 |
| AD9057-80 | Circular Connector; MIL SPEC:MIL-C-26482, Series I, Solder; Body Material:Aluminum; Series:PT06; No. of Contacts:19; Connector Shell Size:14; Connecting Termination:Solder; Circular Shell Style:Straight Plug; Body Style:Straight |
| AD9058JD | Dual 8-Bit 50 MSPS A/D Converter |
相关代理商/技术参数 |
参数描述 |
|---|---|
| AD9057-PCB | 制造商:AD 制造商全称:Analog Devices 功能描述:8-Bit 40 MSPS/50 MSPS/80 MSPS Converter |
| AD9058 | 制造商:AD 制造商全称:Analog Devices 功能描述:Dual 8-Bit 50 MSPS A/D Converter |
| AD9058-803D | 制造商:Analog Devices 功能描述:- Rail/Tube |
| AD9058AJD | 功能描述:IC ADC 8BIT DUAL 50MSPS 48-CDIP RoHS:否 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1 系列:- 位数:14 采样率（每秒）:83k 数据接口:串行，并联 转换器数目:1 功率耗散（最大）:95mW 电压电源:双 ± 工作温度:0°C ~ 70°C 安装类型:通孔 封装/外壳:28-DIP（0.600"，15.24mm） 供应商设备封装:28-PDIP 包装:管件 输入数目和类型:1 个单端，双极 |
| AD9058AJJ | 功能描述:IC ADC 8BIT DUAL 50MSPS 44-JLCC RoHS:否 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1 系列:- 位数:14 采样率（每秒）:83k 数据接口:串行，并联 转换器数目:1 功率耗散（最大）:95mW 电压电源:双 ± 工作温度:0°C ~ 70°C 安装类型:通孔 封装/外壳:28-DIP（0.600"，15.24mm） 供应商设备封装:28-PDIP 包装:管件 输入数目和类型:1 个单端，双极 |
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