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| 型号： | AD7682BCPZRL7 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 15/32页 |
| 文件大小： | 0K |
| 描述： | IC ADC 16BIT 4CH 250KSPS 20LFCSP |
| 产品培训模块： | Power Line Monitoring |
| 产品变化通告： | Startup Circuitry Design Improvement Change 15/April/2009 |
| 标准包装： | 1,500 |
| 系列： | PulSAR® |
| 位数： | 16 |
| 采样率（每秒）： | 250k |
| 数据接口： | DSP，MICROWIRE?，QSPI?，串行，SPI? |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 21mW |
| 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： | 20-VFQFN 裸露焊盘，CSP |
| 供应商设备封装： | 20-LFCSP-VQ |
| 包装： | 带卷 (TR) |
| 输入数目和类型： | 8 个单端，单极；4 个差分，双极；4 个伪差分，双极 |
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AD7682/AD7689
Data Sheet
Rev. D | Page 22 of 32
External Reference and Internal Buffer
For improved drift performance, an external reference can be
used with the internal buffer, as shown in Figure 32. The
external source is connected to REFIN, the input to the on-chip
unity gain buffer, and the output is produced on the REF pin.
An external reference can be used with the internal buffer with
or without the temperature sensor enabled. Refer to Table 10 for
register details. With the buffer enabled, the gain is unity and
is limited to an input/output of VDD = 0.2 V; however, the
maximum voltage allowable must be ≤(VDD 0.5 V).
The internal reference buffer is useful in multiconverter appli-
cations because a buffer is typically required in these applications.
In addition, a low power reference can be used because the
internal buffer provides the necessary performance to drive the
REF
GND
TEMP
AD7682/
AD7689
10F
100nF
REFIN
REF SOURCE
≤ (VDD – 0.5V)
Figure 32. External Reference Using Internal Buffer
External Reference
In any of the six voltage reference schemes, an external reference
can be connected directly on the REF pin as shown in Figure 33
because the output impedance of REF is >5 kΩ. To reduce power
consumption, the reference and buffer should be powered down.
Refer to Table 10 for register details. For improved drift
performance, an external reference such as the ADR43x or
ADR44x is recommended.
REF
GND
TEMP
10F
REFIN
REF SOURCE
0.5V < REF < (VDD + 0.3V)
NO CONNECTION
REQUIRED
07
35
3-
0
47
AD7682/
AD7689
Figure 33.External Reference
Note that the best SNR is achieved with a 5 V external reference
as the internal reference is limited to 4.096 V. The SNR
degradation is as follows:
5
096
.
4
log
20
=
LOSS
SNR
Reference Decoupling
Whether using an internal or external reference, the AD7682/
AD7689 voltage reference output/input, REF, has a dynamic
input impedance and should therefore be driven by a low
impedance source with efficient decoupling between the REF
and GND pins. This decoupling depends on the choice of the
voltage reference but usually consists of a low ESR capacitor
connected to REF and GND with minimum parasitic inductance.
A 10 μF (X5R, 1206 size) ceramic chip capacitor is appropriate
external reference, or a low impedance buffer such as the
The placement of the reference decoupling capacitor is also impor-
the Layout section. Mount the decoupling capacitor on the same
side as the ADC at the REF pin with a thick PCB trace. The GND
should also connect to the reference decoupling capacitor with
the shortest distance and to the analog ground plane with
several vias.
If desired, smaller reference decoupling capacitor values down
to 2.2 μF can be used with a minimal impact on performance,
especially on DNL.
Regardless, there is no need for an additional lower value ceramic
decoupling capacitor (for example, 100 nF) between the REF
and GND pins.
other PulSAR devices, it is more effective to use the internal
reference buffer to buffer the external reference voltage, thus
reducing SAR conversion crosstalk.
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 ±10 ppm/°C TC of the reference changes full scale by ±1 LSB/°C.
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| AD7683 | 制造商:AD 制造商全称:Analog Devices 功能描述:16-Bit, 100 kSPS PulSAR ADC in MSOP/QFN |
| AD7683ACPZRL | 功能描述:IC ADC 16BIT SRL 100KSPS 8LFCSP 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:1,000 系列:- 位数:16 采样率（每秒）:45k 数据接口:串行 转换器数目:2 功率耗散（最大）:315mW 电压电源:模拟和数字 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC W 包装:带卷 (TR) 输入数目和类型:2 个单端，单极 |
| AD7683ACPZRL7 | 功能描述:IC ADC 16BIT 100KSPS 8LFCSP 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:1,000 系列:- 位数:16 采样率（每秒）:45k 数据接口:串行 转换器数目:2 功率耗散（最大）:315mW 电压电源:模拟和数字 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC W 包装:带卷 (TR) 输入数目和类型:2 个单端，单极 |
| AD7683ARM | 制造商:Analog Devices 功能描述:ADC Single SAR 100ksps 16-bit Serial 8-Pin MSOP Tube |
| AD7683ARMRL7 | 制造商:Analog Devices 功能描述:ADC Single SAR 100ksps 16-bit Serial 8-Pin MSOP T/R |
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