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| 型号： | AD7666ACPZRL |
| 厂商： | Analog Devices Inc |
| 文件页数： | 11/28页 |
| 文件大小： | 0K |
| 描述： | IC ADC 16BIT UNIPOLAR 48LFCSP |
| 标准包装： | 2,500 |
| 系列： | PulSAR® |
| 位数： | 16 |
| 采样率（每秒）： | 500k |
| 数据接口： | 串行，并联 |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 75mW |
| 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-VFQFN 裸露焊盘，CSP |
| 供应商设备封装： | 48-LFCSP-VQ（7x7） |
| 包装： | 带卷 (TR) |
| 输入数目和类型： | 2 个伪差分，单极 |
| 配用： | EVAL-AD7666CBZ-ND - BOARD EVALUATION FOR AD7666 |
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AD7666
Rev. 0 | Page 19 of 28
The noise generated by the driver amplifier needs to be
kept as low as possible in order to preserve the SNR and
transition noise performance of the AD7666. The noise
coming from the driver is filtered by the AD7666 analog
input circuit, 1-pole, low-pass filter made by R1 and C2 or
by the external filter, if one is used. The SNR degradation
due to the amplifier is
π
+
=
2
3
)
(
2
784
28
log
20
N
dB
LOSS
Ne
f
SNR
where:
f–3dB
is the input bandwidth of the AD7666 (13 MHz) or
the cutoff frequency of the input filter (3.9 MHz), if
one is used.
N
is the noise factor of the amplifier (+1 in buffer
configuration).
eN
is the equivalent input noise voltage of the op amp, in
nV/√Hz.
For instance, a driver with an equivalent input noise of
2 nV/√Hz, like the AD8021 with a noise gain of +1 when
configured as a buffer, degrades the SNR by only 0.13 dB
when using the filter shown in Figure 26, and by 0.43 dB
without the filter shown in Figure 26.
The driver needs to have a THD performance suitable to
that of the AD7666. Figure 15 gives the THD versus
frequency that the driver should exceed.
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 AD8022 could also be used if a dual version is needed and
gain of 1 is present. The AD829 is an alternative in applications
where high frequency (above 100 kHz) performance is not
required. In gain of 1 applications, it requires an 82 pF
compensation capacitor. The AD8610 is an option when low
bias current is needed in low frequency applications.
Voltage Reference Input
The AD7666 allows the choice of either a very low temperature
drift internal voltage reference or an external 2.5 V reference.
Unlike many ADCs with internal references, the internal
reference of the AD7666 provides excellent performance and
can be used in almost all applications.
To use the internal reference along with the internal buffer,
PDREF and PDBUF should both be LOW. This will produce
1.2 V on REFBUFIN which, amplified by the buffer, will result
in a 2.5 V reference on the REF pin.
The output impedance of REFBUFIN is 11 k (minimum) when
the internal reference is enabled. It is necessary to
decouple
REFBUFIN with a ceramic capacitor greater than 10 nF. Thus
the capacitor provides an RC filter for noise reduction.
To use an external reference along with the internal buffer,
PDREF should be HIGH and PDBUF should be LOW. This
powers down the internal reference and allows the 2.5 V
reference to be applied to REFBUFIN.
To use an external reference directly on REF pin, PDREF and
PDBUF should both be HIGH.
PDREF and PDBUF power down the internal reference and the
internal reference buffer, respectively. Note that the PDREF and
PDBUF input current should never exceed 20 mA. This could
eventually occur when input voltage is above AVDD (for
instance at power up). In this case, a 100 series resistor is
recommended.
The internal reference is temperature compensated to 2.5 V
± 7 mV. The reference is trimmed to provide a typical drift of
3 ppm/°C . This typical drift characteristic is shown in
Figure 22. For improved drift performance, an external
reference, such as the AD780, can be used.
The AD7666 voltage reference input REF has a dynamic input
impedance; it should therefore 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 tantalum
capacitor connected to REF and REFGND, with minimum
parasitic inductance. A 10 F (X5R, 1206 size) ceramic chip
capacitor (or 47 F 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
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相关代理商/技术参数 |
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|---|---|
| AD7666AST | 制造商:Analog Devices 功能描述:ADC Single SAR 500ksps 16-bit Parallel/Serial 48-Pin LQFP 制造商:Rochester Electronics LLC 功能描述:500KSPS, 16-BIT ACD INT. REF, 2.5LSB - Tape and Reel 制造商:Analog Devices 功能描述:16BIT ADC INT REF 7666 LQFP48 |
| AD7666ASTRL | 制造商:Analog Devices 功能描述:ADC Single SAR 500ksps 16-bit Parallel/Serial 48-Pin LQFP T/R |
| AD7666ASTZ | 功能描述:IC ADC 16BIT UNIPOLAR 48LQFP RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:PulSAR® 其它有关文件:TSA1204 View All Specifications 标准包装:1 系列:- 位数:12 采样率（每秒）:20M 数据接口:并联 转换器数目:2 功率耗散（最大）:155mW 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-TQFP 供应商设备封装:48-TQFP（7x7） 包装:Digi-Reel® 输入数目和类型:4 个单端，单极；2 个差分，单极 产品目录页面:1156 (CN2011-ZH PDF) 其它名称:497-5435-6 |
| AD7666ASTZRL | 功能描述:IC ADC 16BIT UNIPOLAR 48LQFP 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:12 采样率（每秒）:300k 数据接口:并联 转换器数目:1 功率耗散（最大）:75mW 电压电源:单电源 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:24-SOIC（0.295"，7.50mm 宽） 供应商设备封装:24-SOIC 包装:带卷 (TR) 输入数目和类型:1 个单端，单极；1 个单端，双极 |
| AD7667 | 制造商:AD 制造商全称:Analog Devices 功能描述:16-Bit 1 MSPS SAR Unipolar ADC with Ref |
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