参数资料
| 型号： | AD9742ACPZRL7 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 8/32页 |
| 文件大小： | 0K |
| 描述： | IC DAC 12BIT 210MSPS 32-LFCSP |
| 产品培训模块： | Data Converter Fundamentals DAC Architectures |
| 标准包装： | 1,500 |
| 系列： | TxDAC® |
| 设置时间： | 11ns |
| 位数： | 12 |
| 数据接口： | 并联 |
| 转换器数目： | 1 |
| 电压电源： | 模拟和数字 |
| 功率耗散（最大）： | 145mW |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-VFQFN 裸露焊盘，CSP |
| 供应商设备封装： | 32-LFCSP-VQ（5x5） |
| 包装： | 带卷 (TR) |
| 输出数目和类型： | 2 电流，单极；2 电流，双极 |
| 采样率（每秒）： | 210M |
| 配用： | AD9742ACP-PCBZ-ND - BOARD EVAL FOR AD9742ACP |
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AD9742
Data Sheet
Rev. C | Page 16 of 32
APPLYING THE AD9742
Output Configurations
The following sections illustrate some typical output configurations
for the AD9742. Unless otherwise noted, it is assumed that IOUTFS is
set to a nominal 20 mA. For applications requiring the optimum
dynamic performance, a differential output configuration is
suggested. A differential output configuration may consist of
either an RF transformer or a differential op amp configuration.
The transformer configuration provides optimum high frequency
performance and is recommended for any application that allows
ac coupling. The differential op amp configuration is suitable
for applications requiring dc coupling, a bipolar output, signal
gain, and/or level shifting within the bandwidth of the chosen
op amp.
A single-ended output is suitable for applications requiring a
unipolar voltage output. A positive unipolar output voltage will
result if IOUTA and/or IOUTB are connected to an appropriately
sized load resistor, RLOAD, referred to ACOM. This configuration
may be more suitable for a single-supply system requiring a
dc-coupled, ground-referred output voltage. Alternatively, an
amplifier could be configured as an I-V converter, thus converting
IOUTA or IOUTB into a negative unipolar voltage. This
configuration provides the best dc linearity since IOUTA or
IOUTB is maintained at a virtual ground.
DIFFERENTIAL COUPLING USING A TRANSFORMER
An RF transformer can be used to perform a differential-to-single-
ended signal conversion, as shown in Figure 31. A differentially
coupled transformer output provides the optimum distortion
performance for output signals whose spectral content lies within
the transformer’s pass band. An RF transformer, such as the
Mini-Circuits T1–1T, provides excellent rejection of common-
mode distortion (that is, even-order harmonics) and noise over
a wide frequency range. It also provides electrical isolation and
the ability to deliver twice the power to the load. Transformers with
different impedance ratios may also be used for impedance matching
purposes. Note that the transformer provides ac coupling only.
RLOAD
AD9742
MINI-CIRCUITS
T1-1T
OPTIONAL RDIFF
IOUTA
IOUTB
22
21
02912-B-030
Figure 31. Differential Output Using a Transformer
The center tap on the primary side of the transformer must be
connected to ACOM to provide the necessary dc current path
for both IOUTA and IOUTB. The complementary voltages
appearing at IOUTA and IOUTB (i.e., VOUTA and VOUTB) swing
symmetrically around ACOM and should be maintained with the
specified output compliance range of the AD9742. A differential
resistor, RDIFF, may be inserted in applications where the output
of the transformer is connected to the load, RLOAD, via a passive
reconstruction filter or cable. RDIFF is determined by the
transformer’s impedance ratio and provides the proper source
termination that results in a low VSWR. Note that approximately
half the signal power will be dissipated across RDIFF.
DIFFERENTIAL COUPLING USING AN OP AMP
An op amp can also be used to perform a differential-to-single-
ended conversion, as shown in Figure 32. The AD9742 is configured
with two equal load resistors, RLOAD, of 25 . The differential
voltage developed across IOUTA and IOUTB is converted to a
single-ended signal via the differential op amp configuration.
An optional capacitor can be installed across IOUTA and IOUTB,
forming a real pole in a low-pass filter. The addition of this
capacitor also enhances the op amp’s distortion performance by
preventing the DAC’s high slewing output from overloading the
op amp’s input.
AD9742
IOUTA
IOUTB
COPT
500
225
225
500
25
25
AD8047
02912-B-031
22
21
Figure 32. DC Differential Coupling Using an Op Amp
The common-mode rejection of this configuration is typically
determined by the resistor matching. In this circuit, the
differential op amp circuit using the AD8047 is configured to
provide some additional signal gain. The op amp must operate
off a dual supply since its output is approximately ±1 V. A high
speed amplifier capable of preserving the differential performance
of the AD9742 while meeting other system level objectives (e.g.,
cost or power) should be selected. The op amp’s differential gain,
gain setting resistor values, and full-scale output swing capabilities
should all be considered when optimizing this circuit.
The differential circuit shown in Figure 33 provides the necessary
level shifting required in a single-supply system. In this case,
AVDD, which is the positive analog supply for both the AD9742
and the op amp, is also used to level shift the differential output
of the AD9742 to midsupply (i.e., AVDD/2). The AD8041 is a
suitable op amp for this application.
AD9742
IOUTA
IOUTB
COPT
500
225
225
1k
25
25
AD8041
1k
AVDD
22
21
02912-B-032
Figure 33. Single-Supply DC Differential Coupled Circuit
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PDF描述 |
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相关代理商/技术参数 |
参数描述 |
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| AD9742AR | 功能描述:IC DAC 12BIT 210MSPS 28-SOIC RoHS:否 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:TxDAC® 标准包装:47 系列:- 设置时间:2µs 位数:14 数据接口:并联 转换器数目:1 电压电源:单电源 功率耗散（最大）:55µW 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:28-SSOP（0.209"，5.30mm 宽） 供应商设备封装:28-SSOP 包装:管件 输出数目和类型:1 电流，单极；1 电流，双极 采样率（每秒）:* |
| AD9742ARRL | 制造商:Analog Devices 功能描述:DAC 1-CH Segment 12-bit 28-Pin SOIC W T/R |
| AD9742ARU | 功能描述:IC DAC 12BIT 210MSPS 28-TSSOP RoHS:否 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:TxDAC® 标准包装:47 系列:- 设置时间:2µs 位数:14 数据接口:并联 转换器数目:1 电压电源:单电源 功率耗散（最大）:55µW 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:28-SSOP（0.209"，5.30mm 宽） 供应商设备封装:28-SSOP 包装:管件 输出数目和类型:1 电流，单极；1 电流，双极 采样率（每秒）:* |
| AD9742ARURL7 | 功能描述:IC DAC 12BIT 210MSPS 28-TSSOP RoHS:否 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:TxDAC® 标准包装:47 系列:- 设置时间:2µs 位数:14 数据接口:并联 转换器数目:1 电压电源:单电源 功率耗散（最大）:55µW 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:28-SSOP（0.209"，5.30mm 宽） 供应商设备封装:28-SSOP 包装:管件 输出数目和类型:1 电流，单极；1 电流，双极 采样率（每秒）:* |
| AD9742ARUZ | 功能描述:IC DAC 12BIT 210MSPS 28-TSSOP RoHS:是 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:TxDAC® 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:50 系列:- 设置时间:4µs 位数:12 数据接口:串行 转换器数目:2 电压电源:单电源 功率耗散（最大）:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 供应商设备封装:8-uMAX 包装:管件 输出数目和类型:2 电压，单极 采样率（每秒）:* 产品目录页面:1398 (CN2011-ZH PDF) |
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