AD7765: 24位、156 kSPS、112 dB Σ-Δ型ADC,内置片内缓冲和串行接口
AD7765是一款高性能、24位Σ-Δ模数转换器（ADC）,融合了宽输入带宽、高速特性,156 kHz输出数据速率时动态范围为112 dB。该转换器具有出色的直流规格,非常适合在同时需要直流数据的情况下对交流信号进行高速数据采集。
利用AD7765可降低前端抗混叠滤波要求,从而大大简化设计过程。AD7765提供128×和256×的抽取率,可通过引脚来选择。其它特性包括：集成缓冲用来驱动基准电压,以及集成完全差动放大器用来缓冲调制器输入并进行电平转换。当输入信号超出了可接受范围时,超量程提醒引脚会给出提示。AD7765还集成了内部增益与内部超量程寄存器,使之成为一款高度集成的紧凑型数据采集器件,只需极少的外围元件。AD7765还提供低功耗模式,可显著降低功耗,但不会降低输出数据速率或可用输入带宽。差分输入由模拟调制器以最高40 MSPS的采样速率进行采样。调制器输出由一系列低通滤波器处理。AD7765的采样速率、滤波器转折频率和输出字速率由外部时钟频率决定。
AD7765拥有全频片内FIR滤波器,可在奈奎斯特（Nyquist）频率点上获得滤波器的全阻带衰减,此特性可更好地防止大于Nyquist频率的信号混叠回馈到输入信号带宽中。
输入范围取决于AD7765采用的基准电压。当基准电压为4 V时,模拟输入范围为基于2.048 V共模电压的±3.2768 V差分偏置电压。此共模偏置可利用片内差分放大器来实现,从而可进一步降低外部信号调理要求。AD7765采用28引脚TSSOP封装,额定温度范围为−40°C至+85°C工业温度范围。
The AD7765 is a high performance, 24-bit Σ-Δ analog-to-digital converter (ADC). It combines wide input bandwidth, high speed, and performance of 112 dB dynamic range at a 156 kHz output data rate. With excellent dc specifications, the converter is ideal for high speed data acquisition of ac signals where dc data is also required.Using the AD7765 eases the front-end antialias filtering requirements, simplifying the design process significantly. The AD7765 offers pin-selectable decimation rates of 128× and 256×. Other features include an integrated buffer to drive the reference as well as a fully differential amplifier to buffer and level shift the input to the modulator.
An overrange alert pin indicates when an input signal has exceeded the acceptable range. The addition of internal gain and internal overrange registers make the AD7765 a compact, highly integrated data acquisition device requiring minimal peripheral components.
The AD7765 also offers a low power mode, significantly reducing power dissipation without reducing the output data rate or available input bandwidth. The differential input is sampled at up to 40 MSPS by an analog modulator. The modulator output is processed by a series of low-pass filters. The external clock frequency applied to the AD7765 determines the sample rate, filter corner frequencies, and output word rate.
The AD7765 device boasts a full band on-board FIR filter. The full stop-band attenuation of the filter is achieved at the Nyquist frequency. This feature offers increased protection from signals that lie above the Nyquist frequency being aliased back into the input signal bandwidth.
The reference voltage supplied to the AD7765 determines the input range. With a 4 V reference, the analog input range is ±3.2768 V differential biased around a common mode of 2.048 V. This common-mode biasing can be achieved using the on-chip differential amplifier, further reducing the external signal conditioning requirements.The AD7765 is available in a 28-lead TSSOP package and is specified over the industrial temperature range from −40°C to +85°C.
AD7765 特点
- 高性能24位Σ-Δ型ADC
- 78 kHz输出数据速率时,动态范围为115 dB
- 156 kHz输出数据速率时,动态范围为112 dB
- 最大完全滤波输出字速率：156 kHz
- 可通过引脚选择过采样率（128×和256×）
- 低功耗模式
- 灵活的SPI
- 全差分调制器输入
- 片内差动放大器,用于信号缓冲
- 片内基准电压缓冲
- 全频低通有限脉冲响应（FIR）滤波器
- 超量程提醒引脚
- High performance 24-bit Σ-Δ ADC
- 115 dB dynamic range at 78 kHz output data rate
- 112 dB dynamic range at 156 kHz output data rate
- 156 kHz maximum fully filtered output word rate
- Pin-selectable oversampling rate
(128× and 256×) - Low power mode
- Flexible SPI
- Fully differential modulator input
- On-chip differential amplifier for signal buffering
- On-chip reference buffer
- Full band low-pass finite impulse response (FIR) filter
- Overrange alert pin
AD7765 技术指标
- Resolution (Bits): 24bit
- # Chan: 1
- Sample Rate: 40MSPS
- Interface: Ser,SPI
- Analog Input Type: Diff-Uni
- Ain Range: 6.5 V p-p
- ADC Architecture: Sigma-Delta
- Pkg Type: SOP
AD7765 应用领域
- 数据采集系统
- 振动分析
- 仪器仪表
AD7765 功能框图
| 产品型号 | 产品状态 | 封装 | 引脚 | 温度范围 |
|---|---|---|---|---|
| AD7765BRUZ | Prodn | 28 ld TSSOP (4.4mm) | 28 | 工业 |
| AD7765BRUZ-REEL7 | Prodn | 28 ld TSSOP (4.4mm) | 28 | 工业 |
| EVAL-AD7765EBZ | Prodn | EVALUATION BOARDS | 28 | 待定 |
