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| 型号： | AD7440BRTZ-R2 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 11/29页 |
| 文件大小： | 0K |
| 描述： | IC ADC 10BIT W/DIFF INP SOT-23-8 |
| 标准包装： | 1 |
| 位数： | 10 |
| 采样率（每秒）： | 1M |
| 数据接口： | DSP，MICROWIRE?，QSPI?，串行，SPI? |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 9.25mW |
| 电压电源： | 单电源 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | SOT-23-8 |
| 供应商设备封装： | SOT-23-8 |
| 包装： | 标准包装 |
| 输入数目和类型： | 1 个差分，单极 |
| 其它名称： | AD7440BRTZ-R2DKR |
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AD7440/AD7450A
Rev. C | Page 18 of 28
DRIVING DIFFERENTIAL INPUTS
Differential operation requires VIN+ and VIN– to be driven
simultaneously with two equal signals that are 180° out of
phase. The common mode must be set up externally and has a
range determined by VREF, the power supply, and the particular
amplifier used to drive the analog inputs (see Figure 28 and
Figure 29). Differential modes of operation with either an ac or
dc input provide the best THD performance over a wide
frequency range. Because not all applications have a signal
preconditioned for differential operation, there is often a need
to perform single-ended-to-differential conversion.
Differential Amplifier
An ideal method of applying differential drive to the
AD7440/AD7450A is to use a differential amplifier such as the
AD8138. This part can be used as a single-ended-to-differential
amplifier or as a differential-to-differential amplifier. In both
cases, the analog input needs to be bipolar. It also provides
common-mode level shifting and buffering of the bipolar input
signal. Figure 34 shows how the AD8138 can be used as a
single-ended-to-differential amplifier. The positive and negative
outputs of the AD8138 are connected to the respective inputs
on the ADC via a pair of series resistors to minimize the effects
of switched capacitance on the front end of the ADCs. The RC
low-pass filter on each analog input is recommended in ac
applications to remove high frequency components of the
analog input. The architecture of the AD8138 results in outputs
that are very highly balanced over a wide frequency range
without requiring tightly matched external components.
If the analog input source being used has zero impedance, all
four resistors (RG1, RG2, RF1, and RF2) should be the same. If
the source has a 50 Ω impedance and a 50 Ω termination, for
example, the value of RG2 should be increased by 25 Ω to
balance this parallel impedance on the input and thus ensure
that both the positive and negative analog inputs have the same
gain (see Figure 34). The outputs of the amplifier are perfectly
matched, balanced differential outputs of identical amplitude
and are exactly 180° out of phase.
The AD8138 is specified with +3 V, +5 V, and ±5 V power
supplies, but the best results are obtained with a ±5 V supply.
The AD8132 is a lower cost device that could also be used in
this configuration with slight differences in characteristics to
the AD8138 but with similar performance and operation.
03051-A
-034
+2.5V
GND
–2.5V
AD8138
51
Ω
RG1
RS*
C*
RS*
RG2
RF2
VOCM
RF1
3.75V
VIN+
VIN–
VREF
2.5V
1.25V
3.75V
2.5V
1.25V
AD7440/
AD7450A
*MOUNT AS CLOSE TO THE AD7440/AD7450A AS POSSIBLE
AND ENSURE HIGH PRECISION RS AND CS ARE USED.
RS–50Ω; C–1nF
RG1 = RF1 = RF2 = 499Ω; RG2 = 523Ω
EXTERNAL
VREF (2.5V)
Figure 34. Using the AD8138 as a Single-Ended-to-Differential Amplifier
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD7440BRTZ-R22 | 制造商:AD 制造商全称:Analog Devices 功能描述:Differential Input, 1 MSPS ADCs in an 8-Lead SOT-23 |
| AD7440BRTZ-REEL7 | 功能描述:IC ADC 10BIT DIFF 1MSPS SOT23-8 RoHS:是 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:2,500 系列:- 位数:16 采样率（每秒）:15 数据接口:MICROWIRE?，串行，SPI? 转换器数目:1 功率耗散（最大）:480µW 电压电源:单电源 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:38-WFQFN 裸露焊盘 供应商设备封装:38-QFN（5x7） 包装:带卷 (TR) 输入数目和类型:16 个单端，双极；8 个差分，双极 配用:DC1011A-C-ND - BOARD DELTA SIGMA ADC LTC2494 |
| AD7440BRTZ-REEL72 | 制造商:AD 制造商全称:Analog Devices 功能描述:Differential Input, 1 MSPS ADCs in an 8-Lead SOT-23 |
| AD7441 | 制造商:AD 制造商全称:Analog Devices 功能描述:Pseudo Differential, 1MSPS, 12- & 10-Bit ADCs in 8-lead SOT-23 |
| AD7441_10 | 制造商:AD 制造商全称:Analog Devices 功能描述:Pseudo Differential Input, 1 MSPS, 10-/12-Bit ADCs in an 8-Lead SOT-23 |
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