- 您现在的位置：买卖IC网 > PDF目录17031 > EVAL-AD7641CBZ (Analog Devices Inc)BOARD EVALUATION FOR AD7641 PDF资料下载
参数资料
| 型号： | EVAL-AD7641CBZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 10/28页 |
| 文件大小： | 0K |
| 描述： | BOARD EVALUATION FOR AD7641 |
| 产品培训模块： | ADC Applications ADC Architectures ADC DC/AC Performance |
| 标准包装： | 1 |
| 系列： | PulSAR® |
| ADC 的数量： | 1 |
| 位数： | 18 |
| 采样率（每秒）： | 2M |
| 数据接口： | 串行 |
| 输入范围： | ±2.5 V |
| 在以下条件下的电源（标准）： | 2MSPS 带内部基准时为 75mW |
| 工作温度： | -40°C ~ 85°C |
| 已用 IC / 零件： | AD7641 |
| 已供物品： | 板 |
| 相关产品： | AD7641BSTZRL-ND - IC ADC 18BIT 2MSPS SAR 48-LQFP AD7641BCPZRL-ND - IC ADC 18BIT 2MSPS SAR 48-LFCSP AD7641BSTZ-ND - IC ADC 18BIT 2MSPS SAR 48-LQFP AD7641BCPZ-ND - IC ADC 18BIT 2MSPS SAR 48-LFCSP |
第1页第2页第3页第4页第5页第6页第7页第8页第9页当前第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页
AD7641
Rev. 0 | Page 18 of 28
Single-to-Differential Driver
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 AD7641. The noise coming from
the driver is filtered by the AD7641 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
For applications using unipolar analog signals, a single-ended-
to-differential driver, as shown in Figure 26, 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 = 10 Ω
and C = 1 nF provides a corner frequency of 16 MHz.
()
()
+
=
+
2
π
2
π
900
30
20log
N
3dB
N
3dB
LOSS
Ne
f
Ne
f
SNR
If the application can tolerate more noise, the AD8139
differential driver can be used.
0
47
61
-02
7
AD8021
ANALOG INPUT
(UNIPOLAR 0V TO 2.048V)
AD8021
IN+
IN–
AD7641
REF
10F
15
100nF
2.7nF
U2
U1
10pF
5k
590
where:
f–3dB is the input bandwidth of the AD7641 (50 MHz) or
the cutoff frequency of the input RC filter shown in Figure 23
(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.
Figure 26. Single-Ended-to-Differential Driver Circuit
(Internal Reference Buffer Used)
VOLTAGE REFERENCE INPUT
The AD7641 allows the choice of either a very low temperature
drift internal voltage reference or an external reference.
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 0.25 dB when using the RC filter in
Unlike many ADCs with internal references, the internal
reference of the AD7641 provides excellent performance and
can be used in almost all applications.
and by 2.5 dB without it.
Internal Reference (PDBUF = Low, PDREF = Low)
The driver needs to have a THD performance suitable to
that of the AD7641. Figure 13 gives the THD vs. frequency
that the driver should exceed.
To use the internal reference, the PDREF and PDBUF inputs
must both be low. This produces a 1.2 V band gap output on
REFBUFIN, which is amplified by the internal buffer and
results in a 2.048 V reference on the REF pin.
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 internal reference is temperature compensated to 2.048 V ±
10 mV. The reference is trimmed to provide a typical drift of
10 ppm/°C. This typical drift characteristic is shown in Figure 7.
The output resistance of REFBUFIN is 6.33 kΩ (minimum)
when the internal reference is enabled. It is necessary to
decouple this with a ceramic capacitor greater than 100 nF.
Therefore, the capacitor provides an RC filter for noise reduction.
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
Because the output impedance of REFBUFIN is typically
6.33 kΩ, relative humidity (among other industrial contaminates)
can directly affect the drift characteristics of the reference.
Typically, a guard ring is used to reduce the effects of drift
under such circumstances.
AD8610 is an option
when low bias current is needed in low frequency applications.
相关PDF资料 |
PDF描述 |
|---|---|
| DC1571A-B | BOARD SAR ADC LTC2382-16 |
| DC1571A-A | BOARD SAR ADC LTC2383-16 |
| STD17W-5 | WIRE & CABLE MARKERS |
| STD17W-T | WIRE & CABLE MARKERS |
| EVAL-AD7612CBZ | BOARD EVALUATION FOR AD7612 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| EVAL-AD7641EDZ | 功能描述:BOARD EVAL FOR AD7641 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-AD7643CB | 制造商:Analog Devices 功能描述:EVAL BD FOR AD7643 - Bulk |
| EVAL-AD7643CBZ | 功能描述:BOARD EVALUATION FOR AD7643 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-AD7643EDZ | 功能描述:BOARD EVAL FOR AD7643 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-AD7650CB | 制造商:Analog Devices 功能描述:EVAL BD EVAL BD AD765X/AD766X/AD767X - Bulk |
发布紧急采购，3分钟左右您将得到回复。