参数资料
| 型号： | AD7621ASTZRL |
| 厂商： | Analog Devices Inc |
| 文件页数： | 11/32页 |
| 文件大小： | 0K |
| 描述： | IC ADC 16BIT 2MSPS DIFF 48LQFP |
| 标准包装： | 2,000 |
| 系列： | PulSAR® |
| 位数： | 16 |
| 采样率（每秒）： | 2M |
| 数据接口： | 串行，并联 |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 86mW |
| 电压电源： | 模拟和数字 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 48-LQFP |
| 供应商设备封装： | 48-LQFP（7x7） |
| 包装： | 带卷 (TR) |
| 输入数目和类型： | 1 个差分，双极 |
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AD7621
Rev. 0 | Page 19 of 32
External Reference (PDBUF = High, PRBUF = High)
To use an external reference directly on the REF pin, PDREF
and PDBUF should both be high.
For improved drift performance, an external reference, such as
using the external voltage reference are:
SNR and dynamic range improvement (about 1.7 dB)
resulting from the use of a reference voltage very close to
the supply (2.5 V) instead of a typical 2.048 V reference
when the internal reference is used. This is calculated by
=
50
.
2
048
.
2
log
20
SNR
Power savings when the internal reference is powered
down (PBREF = PDBUF = high).
PDREF and PDBUF power down the internal reference and the
internal reference buffer, respectively.
Reference Decoupling
Whether using an internal or external reference, the AD7621
voltage reference input (REF) has a dynamic input impedance;
therefore, it should be driven by a low impedance source with
efficient decoupling between the REF and REFGND inputs.
This decoupling depends on the choice of the voltage reference,
but usually consists of a low ESR capacitor connected to REF
and REFGND with minimum parasitic inductance. A 10 μF
(X5R, 1206 size) ceramic chip capacitor (or 47 μF tantalum
capacitor) is appropriate when using either the internal
reference or one of these recommended reference voltages:
The low power ADR291
The low cost AD1582
The placement of the reference decoupling is also important to
the performance of the AD7621. The decoupling capacitor
should be mounted on the same side as the ADC right at the
REF pin with a thick PCB trace. The REFGND should also
connect to the reference decoupling capacitor with the shortest
distance.
For applications that use multiple AD7621 devices, it is more
effective to use the internal reference buffer in order to buffer
the reference voltage.
The voltage reference temperature coefficient (TC) directly
impacts full scale; therefore, in applications where full-scale
accuracy matters, care must be taken with the TC. For instance,
a ±15 ppm/°C TC of the reference changes full-scale by ±1 LSB/°C.
Temperature Sensor
The TEMP pin measures the temperature of the AD7621. 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
04565-031
ADG779
AD8021
CC
ANALOG INPUT
(UNIPOLAR)
AD7621
IN+
TEMPERATURE
SENSOR
TEMP
Figure 28. Use of the Temperature Sensor
POWER SUPPLY
The AD7621 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 23.
Power Sequencing
The AD7621 is independent of power supply sequencing once
OVDD does not exceed DVDD by more than 0.3 V until
DVDD = 2.3 V during any time; for instance, at power-up or
power-down (see the Absolute Maximum Ratings section).
Additionally, it is very insensitive to power supply variations
over a wide frequency range as shown in Figure 29.
04565-098
FREQUENCY (kHz)
P
S
RR
(dB)
45
75
70
65
60
55
50
1
10
100
1k
10k
EXT REF
INT REF
Figure 29. PSRR vs. Frequency
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相关代理商/技术参数 |
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| AD7621ASTZRL1 | 制造商:AD 制造商全称:Analog Devices 功能描述:16-Bit, 2 LSB INL, 3 MSPS PulSAR?? ADC |
| ad7621xst-u2 | 制造商:Analog Devices 功能描述:16-BIT, 1 LSB INL, 3 MSPS PULSAR- ADC - Bulk |
| AD7622 | 制造商:AD 制造商全称:Analog Devices 功能描述:14-Bit, 1 MSPS, Differential, Programmable Input PulSAR ADC |
| AD7622BCPZ | 功能描述:IC ADC 16BIT DIFFERENTL 48-LFCSP RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:PulSAR® 标准包装:1 系列:- 位数:14 采样率（每秒）:83k 数据接口:串行，并联 转换器数目:1 功率耗散（最大）:95mW 电压电源:双 ± 工作温度:0°C ~ 70°C 安装类型:通孔 封装/外壳:28-DIP（0.600"，15.24mm） 供应商设备封装:28-PDIP 包装:管件 输入数目和类型:1 个单端，双极 |
| AD7622BCPZRL | 功能描述:IC ADC 16BIT DIFFERENTL 48-LFCSP RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:PulSAR® 标准包装:1 系列:- 位数:14 采样率（每秒）:83k 数据接口:串行，并联 转换器数目:1 功率耗散（最大）:95mW 电压电源:双 ± 工作温度:0°C ~ 70°C 安装类型:通孔 封装/外壳:28-DIP（0.600"，15.24mm） 供应商设备封装:28-PDIP 包装:管件 输入数目和类型:1 个单端，双极 |
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