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AS1419F-XT 参数 Datasheet PDF下载

AS1419F-XT图片预览
型号: AS1419F-XT
PDF下载: 下载PDF文件 查看货源
内容描述: 14位, 800ksps的采样A / D转换器,带有关断 [14 Bit, 800ksps Sampling A/D Converter with Shutdown]
分类和应用: 转换器
文件页数/大小: 20 页 / 998 K
品牌: AUSTIN [ AUSTIN SEMICONDUCTOR ]
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ADC  
AS1419  
AS1419A  
Austin Semiconductor, Inc.  
100Ω source resistor to limit the input bandwidth to 1.6MHz.  
The 1000pF capacitor also acts as a charge reservoir for the  
input sample-and-hold and isolates the ADC input from  
sampling glitch sensitive circuitry. High quality capacitors and  
resistors should be used since these components can add  
distortion. NPO and silver mica type dielectric capacitors have  
excellent linearity. Carbon surface mount resistors can also  
generate distortion from self heating and from damage that may  
occur during soldering. Metal film surface mount resistors are  
much less susceptible to both problems.  
Input Range  
The 2.5V input range of theAS1419 is optimized for low  
noise and low distortion. Most op amps also perform well over  
this same range, allowing direct coupling to the analog inputs  
and eliminating the need for special translation circuitry.  
Some applications may require other input ranges. The  
AS1419 differential inputs and reference circuitry can  
accommodate other input ranges often with little or no  
additional circuitry. The following sections describe the  
reference and input circuitry and how they affect the input  
range.  
FIGURE 8a: AS1419 Reference Circuit  
Internal Reference  
The AS1419 has an on-chip, temperature compensated,  
curvature corrected, bandgap reference that is factory trimmed  
to 2.500V. It is connected internally to a reference amplifier and  
is available at VREF (Pin 3) see Figure 8a.A2k resistor is in series FIGURE 8b: Using an External Reference  
with the output so that it can be easily overdriven by an exter-  
nal reference or other circuitry, see Figure 8b. The reference  
amplifier gains the voltage at the VREF pin by 1.625 to create the  
required internal reference voltage. This provides buffering  
between the VREF pin and the high speed capacitive DAC. The  
reference amplifier compensation pin (REFCOMP, Pin 4) must  
be bypassed with a capacitor to ground. The reference  
amplifier is stable with capacitors of 1µF or greater. For the best  
noise performance, a 10µF ceramic or 10µF tantalum in parallel  
with a 0.1µF ceramic is recommended.  
The VREF pin can be driven with a DAC or other means  
shown in Figure 9. This is useful in applications where the peak  
input signal amplitude may vary. The input span of the ADC  
can then be adjusted to match the peak input signal, maximizing  
the signal-to-noise ratio. The filtering of the internal AS1419  
FIGURE 9: Driving VREF with a DAC  
reference amplifier will limit the bandwidth and settling time of  
this circuit.Asettling time of 5ms should be allowed for after a  
reference adjustment.  
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.  
AS1419 & AS1419A  
Rev. 1.5 08/09  
11  
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