AD7746:24位、双通道电容数字转换器

AD7746: 24位、双通道电容数字转换器

AD7745/AD7746均为高分辨率、Σ-Δ电容数字转换器（CDC）,可直接与电容传感器的电容连接进行测量。该芯片还具有高分辨率（24位无失码、最高21位有效分辨率）、高线性度（±0.01%）和高精度（±4 fF工厂校准）等固有特性。AD7745/AD7746的电容输入范围是±4 pF（可变）,同时可接受最大17 pF共模电容（不可变）,后者可以通过一个可编程片内数字电容转换器（CAPDAC）来平衡。AD7745拥有一个电容输入通道,AD7746则拥有两个通道。每个通道均可配置为单端输入或差分输入方式。AD7745/AD7746针对浮动式电容传感器而设计。若需一块极板接地的电容传感器,推荐使用AD7747。这些器件内置一个片内温度传感器,其分辨率为0.1°C,精度为±2°C；还集成片内基准电压源和片内时钟发生器,因此在电容传感器应用中无需任何额外外部元件。两款器件都有一个标准电压输入,当与差分基准电压输入结合使用时,可方便地与一个外部温度传感器（如RTD、热敏电阻或二极管等）接口。AD7745/AD7746均有一个双线式I²C兼容串行接口,二者均可采用2.7 V至5.25 V单电源供电,额定温度范围为–40°C至+125°C汽车电子温度范围,采用16引脚TSSOP封装。

The AD7745/AD7746 are a high resolution, Σ-Δ capacitance-to-digital converter (CDC). The capacitance to be measured is connected directly to the device inputs. The architecture fea-tures inherent high resolution (24-bit no missing codes, up to 21-bit effective resolution), high linearity (±0.01%), and high accuracy (±4 fF factory calibrated). The AD7745/AD7746 capacitance input range is ±4 pF (changing), while it can accept up to 17 pF common-mode capacitance (not changing), which can be balanced by a programmable on-chip, digital-to-capacitance converter (CAPDAC).The AD7745 has one capacitance input channel, while the AD7746 has two channels. Each channel can be configured as single-ended or differential. The AD7745/AD7746 are designed for floating capacitive sensors. For capacitive sensors with one plate connected to ground, the AD7747 is recommended.The parts have an on-chip temperature sensor with a resolution of 0.1°C and accuracy of ±2°C. The on-chip voltage reference and the on-chip clock generator eliminate the need for any external components in capacitive sensor applications. The parts have a standard voltage input, which together with the differential reference input allows easy interface to an external temperature sensor, such as an RTD, thermistor, or diode.

The AD7745/AD7746 have a 2-wire, I²C-compatible serial interface. Both parts can operate with a single power supply from 2.7 V to 5.25 V. They are specified over the automotive temperature range of –40°C to +125°C and are housed in a 16-lead TSSOP package.

AD7746 特点

采用单芯片解决方案的新标准
可与单一或差分浮动式传感器接口
分辨率：最低4 aF（即最高21 ENOB）
精度：4 fF
线性度：0.01%
共模（不可变）电容最大可达17 pF
满量程（可变）电容范围：±4 pF
耐受对地寄生电容：最大60 pF
更新速率：10 Hz～90 Hz
16 Hz时,50 Hz、60 Hz同时抑制
片内温度传感器分辨率：0.1°C,精度：±2°C
电压输入通道
内部时钟振荡器
双线式串行接口（I²C®兼容）
电源：2.7 V至5.25 V单电源工作功耗：0.7 mA
工作温度范围：–40°C～+125°C
16引脚TSSOP封装

New standard in single chip solutions
Interfaces to single or differential floating sensors
Resolution down to 4 aF (that is, up to 21 ENOB)
Accuracy: 4 fF
Linearity: 0.01%
Common-mode (not changing) capacitance up to 17 pF
Full-scale (changing) capacitance range: ±4 pF
Tolerant of parasitic capacitance to ground up to 60 pF
Update rate: 10 Hz to 90 Hz
Simultaneous 50 Hz and 60 Hz rejection at 16 Hz
Temperature sensor on-chip Resolution: 0.1°C, accuracy: ±2°C
Voltage input channel
Internal clock oscillator
2-wire serial interface (I²C®-compatible)
Power 2.7 V to 5.25 V single-supply operation 0.7 mA current consumption
Operating temperature: –40°C to +125°C
16-lead TSSOP package

AD7746 技术指标

Resolution (Bits): 24bit
# Chan: 2
Sample Rate: n/a
Interface: I²C/Ser 2-Wire,Ser
Analog Input Type: Diff-Uni,SE-Uni
Ain Range: (2Vref) p-p,± 4 pF (Delta C)
ADC Architecture: Sigma-Delta
Pkg Type: SOP

AD7746 应用领域

汽车电子、工业和医疗系统,用于：

压力测量
位置传感器
液位传感器
流量计
湿度传感器
杂质检测

AD7746 芯片订购指南

产品型号	产品状态	封装	引脚	温度范围
AD7746ARUZ	Prodn	16 ld TSSOP	16	工业
AD7746ARUZ-REEL	Prodn	16 ld TSSOP	16	工业
AD7746ARUZ-REEL7	Prodn	16 ld TSSOP	16	工业
EVAL-AD7746EBZ	Prodn	EVALUATION BOARDS	-	工业
EVAL-AD7746LDZ	Prodn	EVALUATION BOARDS	-	待定