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参数资料
| 型号： | EVAL-AD7676CBZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 5/20页 |
| 文件大小： | 0K |
| 描述： | BOARD EVALUATION FOR AD7676 |
| 标准包装： | 1 |
| 系列： | PulSAR® |
| ADC 的数量： | 1 |
| 位数： | 16 |
| 采样率（每秒）： | 500k |
| 数据接口： | 串行，并联 |
| 输入范围： | ±VREF |
| 在以下条件下的电源（标准）： | 67mW @ 500kSPS |
| 工作温度： | -40°C ~ 85°C |
| 已用 IC / 零件： | AD7676 |
| 已供物品： | 板 |
| 相关产品： | AD7676ASTZRL-ND - IC ADC 16BIT DIFF INP 48LQFP AD7676ASTZ-ND - IC ADC 16BIT 500KSPS DIFF 48LQFP |
REV. B
AD7676
–13–
VREF , as mentioned in the specification table, could be increased
to AVDD – 1.85 V. The benefit here is the increased SNR obtained
as a result of this increase. Since the input range is defined in
terms of VREF, this would essentially increase the range to make
it a
±3 V input range with an AVDD above 4.85 V. The theo-
retical improvement as a result of this increase in reference is
1.58 dB (20 log [3/2.5]). Due to the theoretical quantization noise,
however, the observed improvement is approximately 1 dB. The
AD780 can be selected with a 3 V reference voltage.
Power Supply
The AD7676 uses three sets of power supply pins: an analog 5 V
supply AVDD, a digital 5 V core supply DVDD, and a digital
input/output interface supply OVDD. The OVDD supply 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 5. The AD7676 is
independent of power supply sequencing once OVDD does not
exceed DVDD by more than 0.3 V and thus free from supply
voltage-induced latch-up. Additionally, it is very insensitive to
power supply variations over a wide frequency range, as shown in
Figure 9.
FREQUENCY – Hz
75
PSRR
–
dB
35
65
10k
10M
1k
1M
55
100k
45
70
60
50
40
Figure 9. PSRR vs. Frequency
POWER DISSIPATION
The AD7676 automatically reduces its power consumption at
the end of each conversion phase. During the acquisition phase,
the operating currents are very low, which allows a significant
power savings when the conversion rate is reduced, as shown in
Figure 10. This feature makes the AD7676 ideal for very low
power battery-operated applications.
It should be noted that the digital interface remains active even
during the acquisition phase. To reduce the operating digital
supply currents even further, the digital inputs need to be driven
close to the power rails (i.e., DVDD and DGND) and OVDD
should not exceed DVDD by more than 0.3 V.
SAMPLING RATE – SPS
1M
PO
WER
DISSIP
A
TION
–
W
0.1
10k
100
100k
10
10k
100
1k
1
100k
1k
10
1M
Figure 10. Power Dissipation vs. Sample Rate
CONVERSION CONTROL
Figure 11 shows the detailed timing diagrams of the conversion
process. The AD7676 is controlled by the signal
CNVST, which
initiates conversion. Once initiated, it cannot be restarted or
aborted, even by the power-down input PD, until the conversion
is complete. The
CNVST signal operates independently of CS
and
RD signals.
CNVST
t1
t2
MODE
ACQUIRE
CONVERT
ACQUIRE
CONVERT
t7
t8
BUSY
t4
t3
t5
t6
Figure 11. Basic Conversion Timing
For true sampling applications, the recommended operation of
the
CNVST signal is the following:
CNVST must be held HIGH from the previous falling edge of
BUSY, and during a minimum delay corresponding to the acqui-
sition time t8; then, when CNVST is brought LOW, a conversion
is initiated and the BUSY signal goes HIGH until the comple-
tion of the conversion. Although
CNVST is a digital signal, it
should be designed with this special care with fast, clean edges,
and levels, with minimum overshoot and undershoot or ringing.
For applications where the SNR is critical, the
CNVST signal
should have a very low jitter. To achieve this, some use a dedicated
oscillator for
CNVST generation or, at least, to clock it with a
high frequency low jitter clock as shown in Figure 5.
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| EVAL-AD7676EDZ | 功能描述:BOARD EVAL FOR AD7676 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-AD7677CB | 制造商:AD 制造商全称:Analog Devices 功能描述:Evaluation Board AD766X/AD767X |
| EVAL-AD7677CBZ | 功能描述:BOARD EVALUATION FOR AD7677 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-AD7677EDZ | 功能描述:BOARD EVAL FOR AD7677 RoHS:是 类别:编程器，开发系统 >> 评估板 - 模数转换器 (ADC) 系列:* 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-AD7678CB | 功能描述:BOARD EVALUATION FOR AD7678 RoHS:否 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 |
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