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参数资料
| 型号： | EVAL-AD7678CBZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 10/28页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL FOR AD7678 |
| 标准包装： | 1 |
| 系列： | PulSAR® |
| ADC 的数量： | 1 |
| 位数： | 18 |
| 采样率（每秒）： | 100k |
| 数据接口： | 串行，并联 |
| 输入范围： | ±VREF |
| 在以下条件下的电源（标准）： | 31mW @ 100kSPS |
| 工作温度： | -40°C ~ 85°C |
| 已用 IC / 零件： | AD7678 |
| 已供物品： | 板 |
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AD7678
Rev. A | Page 18 of 28
The AD8021 meets these requirements and is usually appropri-
ate for almost all applications. The AD8021 needs a 10 pF
external compensation capacitor, which should have good
linearity as an NPO ceramic or mica type.
The AD8022 could be used if a dual version is needed and gain
of 1 is present. The AD829 is an alternative in applications
where high frequency (above 100 kHz) performance is not
required. In gain of 1 applications, it requires an 82 pF
compensation capacitor. The AD8610 is another option when
low bias current is needed in low frequency applications.
Single-to-Differential Driver
For applications using unipolar analog signals, a single-ended-
to-differential driver will allow for a differential input into the
part. The schematic is shown in Figure 24. When provided an
input signal of 0 to VREF, this configuration will produce a
differential ±VREF with midscale at VREF/2.
If the application can tolerate more noise, the AD8138
differential driver can be used.
U2
8.25k
2.5V
AD8021
590
AD7678
IN+
IN– REF
U1
ANALOG INPUT
(UNIPOLAR
0V TO 4.096V)
10pF
AD8021
590
10pF
10
F
100nF
1.82k
REFBUFIN
03084-0-030
Figure 24. Single-Ended-to-Differential Driver Circuit
(Internal Reference Buffer Used)
Voltage Reference
The AD7678 allows the use of an external voltage reference with
or without the internal reference buffer.
Using the internal reference buffer is recommended when
sharing a common reference voltage between multiple ADCs is
desired.
However, the advantages of using the external reference voltage
directly are
The SNR and dynamic range improvement (about 1.7 dB)
resulting from the use of a reference voltage very close to
the supply (5 V) instead of a typical 4.096 V reference
when the internal buffer is used.
The power saving when the internal reference buffer is
powered down (PDBUF HIGH).
To use the internal reference buffer, PDBUF should be LOW. A
2.5 V reference voltage applied on the REFBUFIN input will
result in a 4.096 V reference on the REF pin.
In both cases, the voltage reference input REF has a dynamic
input impedance and therefore requires an efficient decoupling
between REF and REFGND inputs. The decoupling consists of
a low ESR 47 μF tantalum capacitor connected to the REF and
REFGND inputs with minimum parasitic inductance.
Care should also be taken with the reference temperature
coefficient of the voltage reference, which directly affects the
full-scale accuracy if this parameter matters. For instance, a
±4 ppm/°C temperature coefficient of the reference changes the
full scale by ±1 LSB/°C.
Power Supply
The AD7678 uses three sets of power supply pins: an analog 5 V
supply (AVDD), a digital 5 V core supply (DVDD), and a digital
output interface supply (OVDD). The OVDD supply defines
the output logic level and allows direct interface with any logic
working between 2.7 V and DVDD + 0.3 V. To reduce the
number of supplies needed, the digital core (DVDD) can be
supplied through a simple RC filter from the analog supply, as
shown in Figure 21. The AD7678 is independent of power
supply sequencing once OVDD does not exceed DVDD by
more than 0.3 V, and is therefore free from supply voltage
induced latch-up. Additionally, it is very insensitive to power
supply variations over a wide frequency range, as shown in
FREQUECY (kHz)
65
P
S
RR
(dB)
40
100
1000
10000
110
60
55
50
45
03084-0-031
Figure 25. PSRR vs. Frequency
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| EVAL-AD7678EDZ | 功能描述:BOARD EVAL FOR AD7678 RoHS:是 类别:编程器，开发系统 >> 评估板 - 模数转换器 (ADC) 系列:PulSAR® 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:- ADC 的数量:1 位数:12 采样率（每秒）:94.4k 数据接口:USB 输入范围:±VREF/2 在以下条件下的电源（标准）:- 工作温度:-40°C ~ 85°C 已用 IC / 零件:MAX11645 已供物品:板，软件 |
| EVAL-AD7679CB | 制造商:Rochester Electronics LLC 功能描述:AD7679 EVAL BOARD 18BIT 570KSPS ADC - Bulk 制造商:Analog Devices 功能描述:AD7679 EVAL BOARD 18BIT 570KSPS ADC |
| EVAL-AD7679CBZ | 功能描述:BOARD EVALUATION FOR AD7679 RoHS:是 类别:编程器，开发系统 >> 评估板 - 模数转换器 (ADC) 系列:PulSAR® 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:- ADC 的数量:1 位数:12 采样率（每秒）:94.4k 数据接口:USB 输入范围:±VREF/2 在以下条件下的电源（标准）:- 工作温度:-40°C ~ 85°C 已用 IC / 零件:MAX11645 已供物品:板，软件 |
| EVAL-AD7679EDZ | 功能描述:BOARD EVAL FOR AD7679 RoHS:是 类别:编程器，开发系统 >> 评估板 - 模数转换器 (ADC) 系列:PulSAR® 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:- ADC 的数量:1 位数:12 采样率（每秒）:94.4k 数据接口:USB 输入范围:±VREF/2 在以下条件下的电源（标准）:- 工作温度:-40°C ~ 85°C 已用 IC / 零件:MAX11645 已供物品:板，软件 |
| EVAL-AD767XCB | 制造商:AD 制造商全称:Analog Devices 功能描述:Evaluation Board AD766X/AD767X |
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