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| 型号： | AD7864ASZ-3 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 28/28页 |
| 文件大小： | 0K |
| 描述： | IC ADC 12BIT PAR 520K 4CH 44MQFP |
| 标准包装： | 1 |
| 位数： | 12 |
| 采样率（每秒）： | 520k |
| 数据接口： | 并联 |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 120mW |
| 电压电源： | 模拟和数字 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 44-QFP |
| 供应商设备封装： | 44-MQFP（10x10） |
| 包装： | 托盘 |
| 输入数目和类型： | 4 个差分，双极 |
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AD7864
Rev. D | Page 9 of 28
TERMINOLOGY
Channel-to-Channel Isolation
Signal-to-(Noise + Distortion) Ratio
Channel-to-channel isolation is a measure of the level of
crosstalk between channels. It is measured by applying a full-
scale 50 kHz sine wave signal to all nonselected input channels
and determining how much that signal is attenuated in the
selected channel. The figure given is the worst case across all
four channels.
This is the measured ratio of signal-to-(noise + distortion) at
the output of the ADC. The signal is the rms amplitude of the
fundamental. Noise is the rms sum of all nonfundamental signals
up to half the sampling frequency (fS/2), excluding dc. The ratio
depends on the number of quantization levels in the digitization
process; the more levels, the smaller the quantization noise. The
theoretical signal-to-(noise + distortion) ratio for an ideal N-bit
converter with a sine wave input is given by
Relative Accuracy
Relative accuracy, or endpoint nonlinearity, is the maximum
deviation from a straight line passing through the endpoints of
the ADC transfer function.
Signal-to-(Noise + Distortion) = (6.02 N + 1.76) dB
Thus, for a 12-bit converter, this is 74 dB.
Differential Nonlinearity
Total Harmonic Distortion (THD)
This is the difference between the measured and the ideal 1 LSB
change between any two adjacent codes in the ADC.
THD is the ratio of the rms sum of harmonics to the
fundamental. For the AD7864, it is defined as
Positive Full-Scale Error
1
6
5
4
3
2
V
THD
2
log
20
)
dB
(
+
=
This is the deviation of the last code transition (01...110 to 01...111)
from the ideal, 4 × VREF 3/2 LSB (AD7864-1, ±10 V), or 2 ×
VREF 3/2 LSB (AD7864-1, ±5 V range), or VREF 3/2 LSB
(AD7864-3, ±2.5 V range), after the bipolar offset error has
been adjusted out.
where V1 is the rms amplitude of the fundamental, and V2, V3,
V4, V5, and V6 are the rms amplitudes of the second through the
fifth harmonics.
Positive Full-Scale Error (AD7864-2, 0 V to 2.5 V and 0 V to 5 V)
Peak Harmonic or Spurious Noise
This is the deviation of the last code transition (11...110 to 11...111)
from the ideal 2 × VREF 3/2 LSB (AD7864-2, 0 V to 5 V range)
or VREF 3/2 LSB (AD7864-2, 0 V to 2.5 V range), after the
unipolar offset error has been adjusted out.
Peak harmonic or spurious noise is defined as the ratio of the
rms value of the next largest component in the ADC output
spectrum (up to fS/2 and excluding dc) to the rms value of the
fundamental. Normally, the value of this specification is deter-
mined by the largest harmonic in the spectrum, but for parts
where the harmonics are buried in the noise floor, it is a noise peak.
Bipolar Zero Error (AD7864-1, ±10 V/±5 V, AD7864-3, ±2.5 V)
This is the deviation of the midscale transition (all 0s to all 1s)
from the ideal, AGND 1/2 LSB.
Intermodulation Distortion
Unipolar Offset Error (AD7864-2, 0 V to 2.5 V and 0 V to 5 V)
With inputs consisting of sine waves at two frequencies, fa and
fb, any active device with nonlinearities creates distortion products
at sum and difference frequencies of mfa ± nfb, where m, n = 0,
1, 2, 3, and so on. Intermodulation terms are those for which
neither m nor n are equal to zero. For example, second-order
terms include (fa + fb) and (fa fb), whereas third-order terms
include (2 fa + fb), (2 fa fb), (fa + 2 fb), and (fa 2 fb).
This is the deviation of the first code transition (00...000 to
00...001) from the ideal, AGND + 1/2 LSB.
Negative Full-Scale Error (AD7864-1, ±10 V/±5 V, and
AD7864-3, ±2.5 V)
This is the deviation of the first code transition (10...000 to
10...001) from the ideal, 4 × VREF + 1/2 LSB (AD7864-1, ±10 V),
2 × VREF + 1/2 LSB (AD7864-1, ±5 V range) or VREF + 1/2 LSB
(AD7864-3, ±2.5 V range), after bipolar zero error has been
adjusted out.
The AD7864 is tested using the CCIF standard, where two input
frequencies near the top end of the input bandwidth are used.
In this case, the second- and third-order terms are of different
significance. The second-order terms are usually distanced in
frequency from the original sine waves, whereas the third-order
terms are usually at a frequency close to the input frequencies. As
a result, the second- and third-order terms are specified separately.
The calculation of the intermodulation distortion is as per the
THD specification where it is the ratio of the rms sum of the
individual distortion products to the rms amplitude of the funda-
mental expressed in decibels.
Track-and-Hold Acquisition Time
Track-and-hold acquisition time is the time required for the
output of the track-and-hold amplifier to reach its final value,
within ±1/2 LSB, after the end of a conversion (the point at
which the track-and-hold returns to track mode). It also applies
to situations where there is a step input change on the input
voltage applied to the selected VINxA/VINxB input of the AD7864.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD7864ASZ-32 | 制造商:AD 制造商全称:Analog Devices 功能描述:4-Channel, Simultaneous Sampling, High Speed, 12-Bit ADC |
| AD7864ASZ-3REEL | 功能描述:IC ADC 12BIT PAR 520K 4CH 44MQFP RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1,000 系列:- 位数:12 采样率（每秒）:300k 数据接口:并联 转换器数目:1 功率耗散（最大）:75mW 电压电源:单电源 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:24-SOIC（0.295"，7.50mm 宽） 供应商设备封装:24-SOIC 包装:带卷 (TR) 输入数目和类型:1 个单端，单极；1 个单端，双极 |
| AD7864ASZ-3REEL2 | 制造商:AD 制造商全称:Analog Devices 功能描述:4-Channel, Simultaneous Sampling, High Speed, 12-Bit ADC |
| AD7864BS-1 | 制造商:Analog Devices 功能描述:ADC Single SAR 520ksps 12-bit Parallel 44-Pin MQFP 制造商:Analog Devices 功能描述:IC 12-BIT ADC |
| AD7864BS-1REEL | 制造商:Analog Devices 功能描述:ADC Single SAR 520ksps 12-bit Parallel 44-Pin MQFP T/R |
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