参数资料
| 型号： | AD9740ACPZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 6/32页 |
| 文件大小： | 0K |
| 描述： | IC DAC 10BIT 210MSPS 32-LFCSP |
| 产品培训模块： | Data Converter Fundamentals DAC Architectures |
| 标准包装： | 1 |
| 系列： | TxDAC® |
| 设置时间： | 11ns |
| 位数： | 10 |
| 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： | 托盘 |
| 输出数目和类型： | 2 电流，单极；2 电流，双极 |
| 采样率（每秒）： | 210M |
| 产品目录页面： | 785 (CN2011-ZH PDF) |
| 配用： | AD9740ACP-PCBZ-ND - BOARD EVAL FOR AD9740ACP |
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AD9740
Rev. B | Page 14 of 32
150pF
1.2V REF
AVDD
REFLO
CURRENT
SOURCE
ARRAY
REFIO
FS ADJ
AD9740
REFERENCE
CONTROL
AMPLIFIER
3.3V
02
9
1
1-
0
23
Figure 25. External Reference Configuration
REFERENCE CONTROL AMPLIFIER
The AD9740 contains a control amplifier that is used to regulate
the full-scale output current, IOUTFS. The control amplifier is
configured as a V-I converter, as shown in Figure 24, so that its
current output, IREF, is determined by the ratio of the VREFIO and
an external resistor, RSET, as stated in Equation 4. IREF is copied
to the segmented current sources with the proper scale factor to
set IOUTFS, as stated in Equation 3.
The control amplifier allows a wide (10:1) adjustment span of
IOUTFS over a 2 mA to 20 mA range by setting IREF between
62.5 μA and 625 μA. The wide adjustment span of IOUTFS
provides several benefits. The first relates directly to the power
dissipation of the AD9740, which is proportional to IOUTFS (see
the Power Dissipation section). The second relates to a 20 dB
adjustment, which is useful for system gain control purposes.
The small signal bandwidth of the reference control amplifier is
approximately 500 kHz and can be used for low frequency small
signal multiplying applications.
DAC TRANSFER FUNCTION
The AD9740 provides complementary current outputs, IOUTA
and IOUTB. IOUTA provides a near full-scale current output,
IOUTFS, when all bits are high (that is, DAC CODE = 1023), while
IOUTB, the complementary output, provides no current. The
current output appearing at IOUTA and IOUTB is a function of
both the input code and IOUTFS and can be expressed as:
IOUTA = (DAC CODE/1023) × IOUTFS
(1)
IOUTB = (1023 DAC CODE)/1024 × IOUTFS
(2)
where DAC CODE = 0 to 1023 (that is, decimal representation).
As mentioned previously, IOUTFS is a function of the reference
current IREF, which is nominally set by a reference voltage,
VREFIO, and external resistor, RSET. It can be expressed as:
IOUTFS = 32 × IREF
(3)
where
IREF = VREFIO/RSET
(4)
The two current outputs typically drive a resistive load directly
or via a transformer. If dc coupling is required, then IOUTA
and IOUTB should be directly connected to matching resistive
loads, RLOAD, that are tied to analog common, ACOM. Note that
RLOAD can represent the equivalent load resistance seen by
IOUTA or IOUTB, as would be the case in a doubly terminated
50 Ω or 75 Ω cable. The single-ended voltage output appearing
at the IOUTA and IOUTB nodes is simply
VOUTA = IOUTA × RLOAD
(5)
VOUTB = IOUTB × RLOAD
(6)
Note that the full-scale value of VOUTA and VOUTB should not
exceed the specified output compliance range to maintain
specified distortion and linearity performance.
VDIFF = (IOUTA IOUTB) × RLOAD
(7)
Substituting the values of IOUTA, IOUTB, IREF, and VDIFF can be
expressed as:
VDIFF = {(2 × DAC CODE 1023)/1024}
(32 × RLOAD/RSET) × VREFIO
(8)
Equation 7 and Equation 8 highlight some of the advantages of
operating the AD9740 differentially. First, the differential
operation helps cancel common-mode error sources associated
with IOUTA and IOUTB, such as noise, distortion, and dc
offsets. Second, the differential code-dependent current and
subsequent voltage, VDIFF, is twice the value of the single-ended
voltage output (that is, VOUTA or VOUTB), thus providing twice the
signal power to the load.
Note that the gain drift temperature performance for a single-
ended (VOUTA and VOUTB) or differential output (V
B
DIFF
) of the
AD9740 can be enhanced by selecting temperature tracking
resistors for RLOAD and RSET due to their ratiometric relationship,
as shown in Equation 8.
ANALOG OUTPUTS
The complementary current outputs in each DAC, IOUTA,
and IOUTB can be configured for single-ended or differential
operation. IOUTA and IOUTB can be converted into
complementary single-ended voltage outputs, VOUTA and VOUTB,
Function section by Equation 5 through Equation 8. The
differential voltage, VDIFF, existing between VOUTA and VOUTB, can
also be converted to a single-ended voltage via a transformer or
differential amplifier configuration. The ac performance of the
AD9740 is optimum and specified using a differential
transformer-coupled output in which the voltage swing at
IOUTA and IOUTB is limited to ±0.5 V.
The distortion and noise performance of the AD9740 can be
enhanced when it is configured for differential operation. The
common-mode error sources of both IOUTA and IOUTB can
be significantly reduced by the common-mode rejection of a
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD9740ACPZ1 | 制造商:AD 制造商全称:Analog Devices 功能描述:10-Bit, 210 MSPS TxDAC D/A Converter |
| AD9740ACPZRL7 | 功能描述:IC DAC 10BIT 210MSPS 32-LFCSP 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:LTC263x 12-, 10-, and 8-Bit VOUT DAC Family 特色产品:LTC2636 - Octal 12-/10-/8-Bit SPI VOUT DACs with 10ppm/°C Reference 标准包装:91 系列:- 设置时间:4µs 位数:10 数据接口:MICROWIRE?，串行，SPI? 转换器数目:8 电压电源:单电源 功率耗散（最大）:2.7mW 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-WFDFN 裸露焊盘 供应商设备封装:14-DFN-EP（4x3） 包装:管件 输出数目和类型:8 电压，单极 采样率（每秒）:* |
| AD9740AR | 制造商:Analog Devices 功能描述:DAC 1-CH Segment 10-bit 28-Pin SOIC W 制造商:Rochester Electronics LLC 功能描述:10 BIT 165 MSPS TXDAC D/A CONVERTER - Bulk 制造商:Analog Devices 功能描述:Digital-Analog Converter IC Interface Ty |
| AD9740ARRL | 制造商:Analog Devices 功能描述:DAC 1-CH Segment 10-bit 28-Pin SOIC W T/R 制造商:Analog Devices 功能描述:DAC SGL CURRENT STEERING 10-BIT 28SOIC W - Tape and Reel |
| AD9740ARU | 功能描述:IC DAC 10BIT 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）:* |
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