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AD7938: 内置序列器的8通道、1.5 MSPS、12位并行ADC

AD7938/AD7939分别是12位和10位高速、低功耗、逐次逼近型（SAR）模数转换器（ADC），采用2.7 V至5.25 V单电源供电，最高吞吐量达1.5 MSPS。这些器件均内置一个低噪声、宽带宽、差分采样保持放大器，可处理最高达50 MHz的输入频率。AD7938/AD7939具有8个带通道序列器的模拟输入通道，可以通过预先编程选择通道转换顺序，二者均可采用单端、全差分或伪差分模拟输入。转换过程和数据采集过程均通过标准控制输入进行控制，使器件与微处理器和DSP可实现轻松接口。输入信号在CONVST的下降沿进行采样，而转换同时在此处启动。AD7938/AD7939内置一个精确的2.5 V片内基准电压源，可用作模数转换的基准电压源。或者，可将外部基准电压加载至此引脚，为其提供基准电压。这些器件采用先进的设计技术，可在高吞吐量的情况下实现极低的功耗，还提供灵活的功耗管理选项。利用一个片内控制寄存器，用户可以设置不同的工作条件，包括模拟输入范围和配置、输出编码、功耗管理及通道序列化。

The AD7938/AD7939 are 12-bit and 10-bit, high speed, low power, successive approximation (SAR) analog-to-digital converters (ADCs). The parts operate from a single 2.7 V to 5.25 V power supply and feature throughput rates up to 1.5 MSPS. The parts contain a low noise, wide bandwidth, differential track-and-hold amplifier that can handle input frequencies up to 50 MHz.

The AD7938/AD7939 feature eight analog input channels with a channel sequencer that allows a preprogrammed selection of channels to be converted sequentially. These parts can operatewith either single-ended, fully differential, or pseudodifferential analog inputs.

The conversion process and data acquisition are controlled using standard control inputs that allow easy interfacing with microprocessors and DSPs. The input signal is sampled on the falling edge of CONVST and the conversion is also initiated at this point.The AD7938/AD7939 have an accurate on-chip 2.5 V reference that can be used as the reference source for the analog-to-digital conversion. Alternatively, this pin can be overdriven to provide an external reference.

These parts use advanced design techniques to achieve very low power dissipation at high throughput rates. They also feature flexible power management options. An on-chip control register allows the user to set up different operating conditions, including analog input range and configuration, output coding, power management, and channel sequencing.

AD7938 特点

• 额定电压（V DD）：2.7 V至5.25 V
• 功耗最大6 mW（1.5 MSPS、3 V电源） ;最大13.5 mW（1.5 MSPS、5 V电源）
• 软件可配置模拟输入8通道单端输入;4通道全差分输入;4通道伪差分输入;7通道伪差分输入
• 吞吐量：1.5 MSPS
• 8个带序列器的模拟输入通道
• 精确的2.5 V片内基准电压源：最大误差±0.2%（25°C），最大温漂25 ppm/°C
• 信纳比：70 dB（50 kHz输入频率）
• 无流水线延迟高速并行接口 — 字/字节模式
• 完全关断模式：最大2 µA
• 32引脚LFCSP和TQFP封装
• Specified for VDD of 2.7 V to 5.25 V
• Power consumption 6 mW maximum at 1.5 MSPS with 3 V supplies ;13.5 mW maximum at 1.5 MSPS with 5 V supplies
• Software-configurable analog inputs
  8-channel single-ended inputs
  4-channel fully differential inputs
  4-channel pseudo differential inputs
  7-channel pseudo differential inputs

• Throughput rate: 1.5 MSPS
• 8 analog input channels with a sequencer
• Accurate on-chip 2.5 V reference ±0.2% maximum @ 25°C, 25 ppm/°C maximum
• 70 dB SINAD at 50 kHz input frequency
• No pipeline delays High speed parallel interface-word/byte modes
• Full shutdown mode: 2 μA maximum
• 32-lead LFCSP and TQFP packages

AD7938 技术指标

• Resolution (Bits): 12bit
• # Chan: 8
• Sample Rate: 1.5MSPS
• Interface: Byte,Par
• Analog Input Type: Diff-Uni,SE-Uni
• Ain Range: (2Vref) p-p,5V p-p,Uni (Vref),Uni (Vref) x 2,Uni 2.5V,Uni 5.0V
• ADC Architecture: SAR
• Pkg Type: CSP,QFP

AD7938 亮点

1. 高吞吐量、低功耗。
2. 8个带通道序列器的模拟输入。
3. 精确的2.5 V片内基准电压源。
4. 单端、伪差分或全差分模拟输入，可通过软件选择。
5. 利用V DRIVE功能实现单电源供电。利用V DRIVE功能，并行接口可直接连至独立于V DD的3 V或5 V处理器系统。
6. 无流水线延迟。
7. 通过CONVST输入与一次性转换控制可实现对采样时间的精确控制。

AD7938 建议配套产品

• Recommended Driver Amplifiers for the AD7938
  • For a single-ended input drive, we recommend the AD8021 or the dual AD8022.
  • For a differential input drive, we recommend the AD8138 or the ADA4932-1.
• Recommended External Voltage References for the AD7938
  • For a precision 2.5V/3.0V reference, we recommend the AD780.
  • For a precision 2.5V reference, we recommend the ADR421.
  • For a precision 2.048V reference, we recommend the ADR420.
• Recommended Power Solutions
  • For selecting voltage regulator products, use ADIsimPower.
  • For selecting supervisor products, use the Supervisor Parametric Search.

AD7938 功能框图

AD7938 产品选型

产品型号	产品状态	封装	Pins	报价* (1000 pcs.)
AD7938BCP-REEL	Prodn	32 ld LFCSP (5x5mm CP-32-2)	32	$ 7.44
AD7938BCP-REEL7	Prodn	32 ld LFCSP (5x5mm CP-32-2)	32	$ 7.44
AD7938BCPZ	Prodn	32 ld LFCSP (5x5mm CP-32-2)	32	$ 7.44
AD7938BCPZ-REEL7	Prodn	32 ld LFCSP (5x5mm CP-32-2)	32	$ 7.44
AD7938BSU	Prodn	32 ld TQFP (7x7mm)	32	$ 7.44
AD7938BSU-REEL	Prodn	32 ld TQFP (7x7mm)	32	$ 7.44
AD7938BSU-REEL7	Prodn	32 ld TQFP (7x7mm)	32	$ 7.44
AD7938BSUZ	Prodn	32 ld TQFP (7x7mm)	32	$ 7.44
AD7938BSUZ-REEL7	Prodn	32 ld TQFP (7x7mm)	32	$ 7.44
EVAL-AD7938CBZ	Prodn	EVALUATION BOARDS	-	$ 151.80

AD7938 应用技术支持与电子电路设计开发资源下载

1. AD7938 数据手册DataSheet下载 .pdf
2. Analog Devices, Inc.ADI 美国模拟器件公司产品订购手册 .pdf
3. ADC模数转换器选型指南 . pdf