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参数资料
| 型号： | EVAL-AD7612CBZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 13/32页 |
| 文件大小： | 0K |
| 描述： | BOARD EVALUATION FOR AD7612 |
| 标准包装： | 1 |
| 系列： | PulSAR® |
| ADC 的数量： | 1 |
| 位数： | 16 |
| 采样率（每秒）： | 750k |
| 数据接口： | 串行，并联 |
| 输入范围： | ±5 V，±10 V |
| 在以下条件下的电源（标准）： | 205mW @ 750kSPS |
| 工作温度： | -40°C ~ 85°C |
| 已用 IC / 零件： | AD7612 |
| 已供物品： | 板 |
| 相关产品： | AD7612BSTZ-RL-ND - IC ADC 16BIT 750KSPS SAR 48-LQFP AD7612BCPZ-RL-ND - IC ADC 16BIT 750KSPS SAR 48LFCSP AD7612BSTZ-ND - IC ADC 16BIT 750KSPS SAR 48-LQFP AD7612BCPZ-ND - IC ADC 16BIT 750KSPS SAR 48LFCSP |
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AD7612
Data Sheet
Rev. A | Page 20 of 32
ANALOG INPUTS
Input Range Selection
In parallel mode and serial hardware mode, the input range is
selected by using the BIPOLAR (bipolar) and TEN (10 Volt range)
inputs. See Table 6 for pin details and the Hardware Configuration
section and Software Configuration section for programming
the mode selection with either pins or configuration register. Note
that when using the configuration register, the BIPOLAR and
TEN inputs are don’t cares and should be tied to either high or low.
Input Structure
Figure 28 shows an equivalent circuit for the input structure of
the AD7612.
D1
RIN
CIN
D2
IN+ OR IN–
VEE
VCC
CPIN
AGND
D3
D4
AVDD
0TO 5V
RANGE ONLY
0
62
65
-0
28
Figure 28. AD7612 Simplified Analog Input
The four diodes, D1 to D4, provide ESD protection for the analog
inputs, IN+ and IN. Care must be taken to ensure that the analog
input signal never exceeds the supply rails by more than 0.3 V,
because this causes the diodes to become forward-biased and to
start conducting current. These diodes can handle a forward-
biased current of 120 mA maximum. For instance, these conditions
could eventually occur when the input buffer’s U1 supplies are
different from AVDD, VCC, and VEE. In such a case, an input
buffer with a short-circuit current limitation can be used to protect
the part although most op amps’ short circuit current is <100 mA.
Note that D3 and D4 are only used in the 0 V to 5 V range to
allow for additional protection in applications that are switching
from the higher voltage ranges.
This analog input structure allows the sampling of the differential
signal between IN+ and IN. By using this differential input,
small signals common to both inputs are rejected as shown in
Figure 29, which represents the typical CMRR over frequency.
For instance, by using IN to sense a remote signal ground,
ground potential differences between the sensor and the local
ADC ground are eliminated.
100
0
1
10000
FREQUENCY (kHz)
CM
RR
(
d
B)
90
80
70
60
50
40
30
20
10
100
1000
06
26
5-
0
29
Figure 29. Analog Input CMRR vs. Frequency
During the acquisition phase for ac signals, the impedance of
the analog inputs, IN+ and IN, can be modeled as a parallel
combination of Capacitor CPIN and the network formed by the
series connection of RIN and CIN. CPIN is primarily the pin capac-
itance. RIN is typically 70 Ω and is a lumped component comprised
of serial resistors and the on resistance of the switches. CIN is pri-
marily the ADC sampling capacitor and depending on the input
range selected is typically 48 pF in the 0 V to 5 V range, typically
24 pF in the 0 V to 10 V and ±5 V ranges and typically 12 pF in
the ±10 V range. During the conversion phase, when the switches
are opened, the input impedance is limited to CPIN.
Since the input impedance of the AD7612 is very high, it can be
directly driven by a low impedance source without gain error. To
further improve the noise filtering achieved by the AD7612 analog
input circuit, an external, one-pole RC filter between the ampli-
fier’s outputs and the ADC analog inputs can be used, as shown
in Figure 27. However, large source impedances significantly
affect the ac performance, especially total harmonic distortion
(THD). The maximum source impedance depends on the amount
of THD that can be tolerated. The THD degrades as a function
of the source impedance and the maximum input frequency.
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| EVAL-AD7612EDZ | 功能描述:BOARD EVAL FOR AD7612 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 |
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| EVAL-AD7621CB-U1 | 制造商:Analog Devices 功能描述:EVAL FOR AD7621 - Bulk |
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