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參數(shù)資料
| 型號： | AD7862AR-2 |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | ADC |
| 英文描述： | Simultaneous Sampling Dual 250 kSPS 12-Bit ADC |
| 中文描述： | 2-CH 12-BIT SUCCESSIVE APPROXIMATION ADC, PARALLEL ACCESS, PDSO28 |
| 封裝： | SOIC-28 |
| 文件頁數(shù)： | 6/16頁 |
| 文件大小： | 414K |
| 代理商： | AD7862AR-2 |
AD7862
–6–
REV. 0
TERMINOLOGY
Signal to (Noise + Distortion) Ratio
This is the measured ratio of signal to (noise + distortion) at the
output of the A/D converter. The signal is the rms amplitude of
the fundamental. Noise is the rms sum of all nonfundamental
signals up to half the sampling frequency (f
S
/2), excluding dc.
The ratio is dependent upon 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:
Signal to
(
Noise
+
Distortion
) = (6.02
N
+ 1.76)
dB
Thus for a 12-bit converter, this is 74 dB.
Total Harmonic Distortion
Total harmonic distortion (THD) is the ratio of the rms sum of
harmonics to the fundamental. For the AD7862 it is defined as:
THD dB
)
=
20
log
V
2
2
+
V
3
2
+
V
4
V
1
2
+
V
5
2
where
V
1
is the rms amplitude of the fundamental and
V
2
,
V
3
,
V
4
and
V
5
are the rms amplitudes of the second through the fifth
harmonics.
Peak Harmonic or Spurious Noise
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 f
S
/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 will be a
noise peak.
Intermodulation Distortion
With inputs consisting of sine waves at two frequencies, fa and
fb, any active device with nonlinearities will create distortion
products at sum and difference frequencies of mfa
±
nfb where
m, n = 0, 1, 2, 3, etc. Intermodulation terms are those for
which neither
m
nor
n
are equal to zero. For example, the
second order terms include (fa + fb) and (fa – fb), while the
third order terms include (2 fa + fb), (2 fa – fb), (fa + 2 fb) and
(fa – 2 fb).
The AD7862 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, while 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
fundamental expressed in dBs.
Channel-to-Channel Isolation
Channel-to-Channel isolation is a measure of the level of
crosstalk between channels. It is measured by applying a full-
scale 100 kHz sine wave signal to each of the four inputs
individually. These, in turn, are individually referenced to the
other three channels whose inputs are grounded, and the ADC
output is measured to determine the level of crosstalk from the
other channel. The figure given is the worst case across all four
channels.
Relative Accuracy
Relative accuracy or endpoint nonlinearity is the maximum
deviation from a straight line passing through the endpoints of
the ADC transfer function.
Differential Nonlinearity
This is the difference between the measured and the ideal 1LSB
change between any two adjacent codes in the ADC.
Positive Full-Scale Error
This is the deviation of the last code transition (01 . . . 110 to
01 . . . 111) from the ideal 4
×
VREF – 3/2 LSB (AD7862-10
±
10 V range) or VREF – 3/2 LSB (AD7862-3,
±
2.5 V range)
after the Bipolar Offset Error has been adjusted out.
Positive Full-Scale Error (AD7862-2, 0 V to 2.5 V)
This is the deviation of the last code transition (01 . . . 110 to
01 . . . 111) from the ideal VREF – 3/2 LSB after the unipolar
offset error has been adjusted out.
Bipolar Zero Error (AD7862-10,
6
10 V, AD7862-3,
6
2.5 V)
This is the deviation of the midscale transition (all 1s to all 0s)
from the ideal AGND – 1/2 LSB.
Unipolar Offset Error (AD7862-2, 0 V to 2.5 V)
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 (AD7862-1,
6
10 V; AD7862-3,
6
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 (AD7862-10
±
10 V range) or –VREF + 1/2 LSB (AD7862-3,
±
2.5 V range)
after Bipolar Zero Error has been adjusted out.
Track/Hold Acquisition Time
Track/Hold acquisition time is the time required for the output
of the track/hold amplifier to reach its final value, within
±
1/2 LSB, after the end of conversion (the point at which the
track/hold returns to track mode). It also applies to situations
where a change in the selected input channel takes place or
where there is a step input change on the input voltage applied
to the selected V
AX/BX
input of the AD7862. It means that the
user must wait for the duration of the track/hold acquisition
time, after the end of conversion or after a channel change/step
input change to V
AX/BX
, before starting another conversion to
ensure that the part operates to specification.
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| AD7862ARS-2 | Simultaneous Sampling Dual 250 kSPS 12-Bit ADC |
| AD7862ARS-3 | Simultaneous Sampling Dual 250 kSPS 12-Bit ADC |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD7862AR-2REEL | 功能描述:IC ADC 12BIT DUAL 250KSPS 28SOIC RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:1,000 系列:- 位數(shù):12 采樣率（每秒）:300k 數(shù)據(jù)接口:并聯(lián) 轉(zhuǎn)換器數(shù)目:1 功率耗散（最大）:75mW 電壓電源:單電源 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:24-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:24-SOIC 包裝:帶卷 (TR) 輸入數(shù)目和類型:1 個單端，單極；1 個單端，雙極 |
| AD7862AR-3 | 制造商:Analog Devices 功能描述:ADC Dual SAR 250ksps 12-bit Parallel 28-Pin SOIC W 制造商:Rochester Electronics LLC 功能描述:DUAL 12-BIT PARALLEL ADC I.C. - Bulk 制造商:Analog Devices 功能描述:IC DUAL 12-BIT ADC ((NS)) |
| AD7862AR-3REEL | 制造商:Analog Devices 功能描述:ADC Dual SAR 250ksps 12-bit Parallel 28-Pin SOIC W T/R 制造商:Rochester Electronics LLC 功能描述:DUAL 12-BIT PARALLEL ADC I.C. - Tape and Reel |
| AD7862ARS-10 | 功能描述:IC ADC 12BIT DUAL 250KSPS 28SSOP RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 位數(shù):14 采樣率（每秒）:83k 數(shù)據(jù)接口:串行，并聯(lián) 轉(zhuǎn)換器數(shù)目:1 功率耗散（最大）:95mW 電壓電源:雙 ± 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:28-DIP（0.600"，15.24mm） 供應(yīng)商設(shè)備封裝:28-PDIP 包裝:管件 輸入數(shù)目和類型:1 個單端，雙極 |
| AD7862ARS-10REEL | 功能描述:IC ADC 12BIT DUAL 250KSPS 28SSOP RoHS:否 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:- 標(biāo)準(zhǔn)包裝:1,000 系列:- 位數(shù):12 采樣率（每秒）:300k 數(shù)據(jù)接口:并聯(lián) 轉(zhuǎn)換器數(shù)目:1 功率耗散（最大）:75mW 電壓電源:單電源 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:24-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:24-SOIC 包裝:帶卷 (TR) 輸入數(shù)目和類型:1 個單端，單極；1 個單端，雙極 |
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