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| 型号： | EVAL-AD7622CBZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 13/28页 |
| 文件大小： | 0K |
| 描述： | BOARD EVALUATION FOR AD7622 |
| 标准包装： | 1 |
| 系列： | PulSAR® |
| ADC 的数量： | 1 |
| 位数： | 16 |
| 采样率（每秒）： | 2M |
| 数据接口： | 串行，并联 |
| 输入范围： | ±VREF |
| 在以下条件下的电源（标准）： | 70mW @ 2MSPS |
| 工作温度： | -40°C ~ 85°C |
| 已用 IC / 零件： | AD7622 |
| 已供物品： | 板 |
| 相关产品： | AD7622BSTZ-ND - IC ADC 16BIT DIFFERENTIAL 48LQFP AD7622BCPZ-ND - IC ADC 16BIT DIFFERENTL 48-LFCSP AD7622BSTZRL-ND - IC ADC 16BIT DIFFERENTL 48-LQFP AD7622BCPZRL-ND - IC ADC 16BIT DIFFERENTL 48-LFCSP |
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AD7622
Rev. 0 | Page 20 of 28
Temperature Sensor
The TEMP pin measures the temperature of the AD7622. To
improve the calibration accuracy over the temperature range,
the output of the TEMP pin is applied to one of the inputs of
the analog switch (such as, ADG779), and the ADC itself is
used to measure its own temperature. This configuration is
shown in Figure 29.
ADG779
AD8021
CC
ANALOG INPUT
(UNIPOLAR)
AD7622
IN+
TEMPERATURE
SENSOR
TEMP
060
23-
027
Figure 29. Use of the Temperature Sensor
POWER SUPPLY
The AD7622 uses three sets of power supply pins: an analog
2.5 V supply AVDD, a digital 2.5 V core supply DVDD, and a
digital input/output interface supply OVDD. The OVDD supply
allows direct interface with any logic working between 2.3 V
and 5.25 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 24.
Power Sequencing
The AD7622 is independent of power supply sequencing and
thus free from supply induced voltage latch-up. In addition, it is
very insensitive to power supply variations over a wide
frequency range, as shown in Figure 30.
65.0
45.0
1
10000
FREQUENCY (kHz)
PSR
R
(
d
B)
10
100
1000
47.5
50.0
52.5
55.0
57.5
60.0
62.5
0
60
23-
02
9
EXT REF
INT REF
Figure 30. PSRR vs. Frequency
Power-Up
At power-up, or when returning to operational mode from the
power-down mode (PD = high), the AD7622 engages an
initialization process. During this time, the first 128 conversions
should be ignored or the RESET input could be pulsed to
engage a faster initialization process. Refer to the Digital
Interface section for RESET and timing details.
A simple power-on reset circuit, as shown in Figure 24, can be
used to minimize the digital interface. As OVDD powers up, the
capacitor is shorted and brings RESET high; it is then charged
returning RESET to low. However, this circuit only works when
powering up the AD7622 because the power-down mode
(PD = high) does not power down any of the supplies and as a
result, RESET is low.
It should be noted that the digital interface remains active even
during the acquisition phase. To reduce the operating digital
supply currents even further, drive the digital inputs close to
the power rails (that is, OVDD and OGND).
CONVERSION CONTROL
The AD7622 is controlled by the CNVST input. A falling edge
on CNVST is all that is necessary to initiate a conversion.
Detailed timing diagrams of the conversion process are shown
in Figure 31. 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.
BUSY
MODE
CONVERT
ACQUIRE
CONVERT
CNVST
t1
t2
t4
t3
t5
t6
t7
t8
06
02
3-
0
30
Figure 31. Basic Conversion Timing
For optimal performance, the rising edge of CNVST should not
occur after the maximum CNVST low time, t1, or until the end
of conversion.
Although CNVST is a digital signal, it should be designed with
special care with fast, clean edges and levels with minimum
overshoot and undershoot or ringing.
The CNVST trace should be shielded with ground and a low
value serial resistor (for example, 50 Ω) termination should be
added close to the output of the component that drives this line.
In addition, a 50 pF capacitor is recommended to further reduce
the effects of overshoot and undershoot as shown in Figure 24.
For applications where SNR is critical, the CNVST signal should
have very low jitter. This can be achieved by using a dedicated
oscillator for CNVST generation, or by clocking CNVST with a
high frequency, low jitter clock, as shown in Figure 24.
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| EVAL-AD7622EDZ | 功能描述:BOARD EVAL FOR AD7622 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-AD7623CB | 制造商:Analog Devices 功能描述:EVAL KIT FOR 16BIT, 1.33 MSPS PULSAR ADC - Trays |
| EVAL-AD7623CBZ | 功能描述:BOARD EVALUATION FOR AD7623 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-AD7623EDZ | 功能描述:BOARD EVAL FOR AD7623 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-AD7625EDZ | 功能描述:数据转换 IC 开发工具 Eval Board 16-BIT 5MSPS ADC I.C RoHS:否 制造商:Texas Instruments 产品:Demonstration Kits 类型:ADC 工具用于评估:ADS130E08 接口类型:SPI 工作电源电压:- 6 V to + 6 V |
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