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參數(shù)資料
| 型號： | AD7622BSTZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 10/28頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC ADC 16BIT DIFFERENTIAL 48LQFP |
| 標(biāo)準(zhǔn)包裝： | 1 |
| 系列： | PulSAR® |
| 位數(shù)： | 16 |
| 采樣率（每秒）： | 2M |
| 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）： | 85mW |
| 電壓電源： | 模擬和數(shù)字 |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 48-LQFP |
| 供應(yīng)商設(shè)備封裝： | 48-LQFP（7x7） |
| 包裝： | 托盤 |
| 輸入數(shù)目和類型： | 1 個差分，雙極 |
| 配用： | EVAL-AD7622CBZ-ND - BOARD EVALUATION FOR AD7622 |
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AD7622
Rev. 0 | Page 18 of 28
DRIVER AMPLIFIER CHOICE
Although the AD7622 is easy to drive, the driver amplifier
needs to meet the following requirements:
For multichannel, multiplexed applications, the driver
amplifier and the AD7622 analog input circuit must be
able to settle for a full-scale step of the capacitor array at an
16-bit level (0.0015%). In the amplifier’s data sheet, settling
at 0.1% to 0.01% is more commonly specified. This could
differ significantly from the settling time at a 16-bit level
and should be verified prior to driver selection. The
AD8021 op amp, which combines ultralow noise and high
gain bandwidth, meets this settling time requirement even
when used with gains up to 13.
The noise generated by the driver amplifier needs to be
kept as low as possible to preserve the SNR and transition
noise performance of the AD7622. The noise coming from
the driver is filtered by the AD7622 analog input circuit
1-pole, low-pass filter made by RIN and CIN or by the
external filter, if one is used. The SNR degradation due
to the amplifier is
()
()
+
=
+
2
π
2
π
45
20log
N
3dB
N
3dB
LOSS
Ne
f
Ne
f
SNR
where:
f–3dB is the input bandwidth of the AD7622 (50 MHz) or
the cutoff frequency of the input RC filter shown in Figure 24
(3.9 MHz), if one is used.
N is the noise factor of the amplifier (1 in buffer
configuration).
eN+ and eN are the equivalent input voltage noise densities
of the op amps connected to IN+ and IN, in nV/√Hz.
This approximation can be used when the resistances used
around the amplifier are small. If larger resistances are
used, their noise contributions should also be root-sum
squared.
For instance, when using op amps with an equivalent input
noise density of 2.1 nV/√Hz, such as the AD8021, with a
noise gain of 1 when configured as a buffer, degrades the
SNR by only 0.1 dB when using the RC filter in Figure 24,
and by 1.3 dB without it.
The driver needs to have a THD performance suitable to
that of the AD7622. Figure 14 gives the THD vs. frequency
that the driver should exceed.
The AD8021 meets these requirements and is appropriate for
almost all applications. The AD8021 needs a 10 pF external
compensation capacitor that should have good linearity as an
NPO ceramic or mica type. Moreover, the use of a noninverting
1 gain arrangement is recommended and helps to obtain the
best signal-to-noise ratio.
The AD8022 can also be used when a dual version is needed
and a gain of 1 is present. The AD829 is an alternative in
applications where high frequency (above 100 kHz) performance is
not required. In applications with a gain of 1, an 82 pF
compensation capacitor is required. The AD8610 is an option
when low bias current is needed in low frequency applications.
Refer to Table 8 for some recommended op amps.
Table 8. Recommended Driver Amplifiers
Amplifier
Typical Application
Very low noise, low distortion, low power,
low frequency
Very low noise, low frequency
Very low noise, high frequency
Very low noise, high frequency, dual
Low bias current, low frequency, single/dual
Single-to-Differential Driver
For applications using unipolar analog signals, a single-ended-
to-differential driver, as shown in Figure 28, allows for a
differential input into the part. This configuration, when
provided an input signal of 0 to VREF, produces a differential
±VREF with midscale at VREF/2. The 1-pole filter using R = 15 Ω
and C = 2.7nF provides a corner frequency of 3.9 MHz.
If the application can tolerate more noise, the AD8139
differential driver can be used.
AD8021
ANALOG INPUT
(UNIPOLAR 0V TO 2.048V)
AD8021
IN+
IN–
AD7622
REF
10F
15
100nF
2.7nF
U2
U1
10pF
5k
590
0
602
3-
041
Figure 28. Single-Ended-to-Differential Driver Circuit
(Internal Reference Buffer Used)
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| AD7622BSTZRL | 功能描述:IC ADC 16BIT DIFFERENTL 48-LQFP RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:PulSAR® 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 |
| AD7623 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Ultralow Power, Low Distortion |
| AD7623ACP | 制造商:Analog Devices 功能描述:ADC Single SAR 1.33Msps 16-bit Parallel/Serial 48-Pin LFCSP EP 制造商:Rochester Electronics LLC 功能描述:16-BIT, 2LSB, 1.33MSPS ADC - Bulk |
| AD7623ACPRL | 制造商:Analog Devices 功能描述:ADC Single SAR 1.33Msps 16-bit Parallel/Serial 48-Pin LFCSP EP T/R |
| AD7623ACPZ | 功能描述:IC ADC 16BIT 1.33MSPS 48LFCSP RoHS:是 類別:集成電路 (IC) >> 數(shù)據(jù)采集 - 模數(shù)轉(zhuǎn)換器 系列:PulSAR® 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 |
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