EVAL-AD7879EBZ: 用于触摸屏的低成本控制器
The AD7879/AD7889 are 12-bit successive approximation analog-to-digital converters (SAR ADCs) with a synchronous serial interface and low on-resistance switches for driving 4-wire resistive touch screens. The AD7879/AD7889 work with a very low power supply–a single 1.6 V to 3.6 V supply–and feature throughput rates of 105 kSPS. The devices include a shutdown mode that reduces current consumption to less than 6 μA.
To reduce the effects of noise from LCDs and other sources, the AD7879/AD7889 contain a preprocessing block. The prepro-cessing function consists of a median filter and an averaging filter. The combination of these two filters provides a more robust solution, discarding the spurious noise in the signal and keeping only the data of interest. The size of both filters is programmable. Other user-programmable conversion controls include variable acquisition time and first conversion delay; up to 16 averages can be taken per conversion. The AD7879/AD7889 can run in slave mode or standalone (master) mode, using an automatic conversion sequencer and timer.
The AD7879/AD7889 have a programmable pin that can operate as an auxiliary input to the ADC, as a battery monitor, or as a GPIO. In addition, a programmable interrupt output can operate in three modes: as a general-purpose interrupt to signal when new data is available (DAV), as an interrupt to indicate when limits are exceeded (INT), or as a pen-down interrupt when the screen is touched (PENIRQ). The AD7879/AD7889 offer temp-erature measurement and touch-pressure measurement.
The AD7879 is available in a 12-ball, 1.6 mm × 2 mm WLCSP and in a 16-lead, 4 mm × 4 mm LFCSP. The AD7889 is available in a backside-coated version of the WLCSP. Both parts support an SPI interface (AD7879/AD7889) or an I²C® interface (AD7879-1/AD7889-1).
AD7879是一款12-bit逐次逼近型ADC,具有同步串行接口以及用于驱动4线电阻触摸屏的低导通电阻开关。AD7879工作电源电压极低,采用1.6 V～3.6V单电源供电,吞吐率为105 kSPS。
这款器件具有待机模式,待机功耗不足5 µA。
为了降低来自LCD以及其它噪声源的噪声,AD7879内置预处理模块。预处理功能包括中值滤波器及均值滤波器。这两项技术的结合提供了更鲁棒的解决方案,既能滤除信号中的杂散噪声,又能只保留有用的数据。两个滤波器的尺寸都可以设置。用户可设置的其它转换控制包括可变采集时间及第一转换延迟。每次转换可利用多达16个均值。AD7879采用自动转换序列器与定时器,可以工作在从模式或待机模式。
AD7879拥有可编程引脚,可以用作到ADC的辅助输入、电池监控器或通用接口。可编程中断输出有三种工作模式：作为当新数据可用时的通用中断,INT；作为超过限定范围的指示中断信号；或作为屏幕被触摸时的落笔中断, PENIRQ。AD7879可提供温度与触觉压力测量。
AD7879采用1.6mm x 2mm 12引脚WLCSP封装以及4mm x 4mm 16引脚LFCSP封装,具有SPI（AD7879）或II²C（AD7879-1）接口。
Applications
- Personal digital assistants
- Smart hand-held devices
- Touch screen monitors
- Point-of-sales terminals
- Medical devices
- Cell phones
- 个人数字助理
- 智能手持式设备
- 触摸屏监控器
- POS终端机
- 医疗设备
- 蜂窝电话
EVAL-AD7879EBZ 特性
- 4-wire touch screen interface
- 1.6V to 3.6V operation
- Median and averaging filter to reduce noise
- Automatic conversion sequencer and timer
- WLCSP package with backside coating
- User-programmable conversion parameters
- Auxiliary analog input /Battery Monitor (0.5 V to 5 V)
- 1 Optional GPIO
- See data sheet for additional features.
- 4线触摸屏接口
- 电源电压：1.6V～3.6V
- 中值滤波器与均值滤波器,用于降低噪声
- 自动转换序列器与定时器
- 用户可编程的转换参数
- 辅助模拟输入/电池监控器（0.5 V～5 V）
- 1个可选的通用接口（GPIO ）
- 中断输出（INT,PENIRQ）
EVAL-AD7879EBZ 功能框图
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| 产品型号 | 产品状态 | 封装 | 引脚 | 温度范围 |
|---|---|---|---|---|
| AD7879-1ACPZ-RL | 量产 | 16 ld LFCSP (4x4mm, 2.35mm exposed pad) | 16 | 工业 |
| AD7879ACPZ-RL | 量产 | 16 ld LFCSP (4x4mm, 2.35mm exposed pad) | 16 | 工业 |
| EVAL-AD7879-1EBZ | 量产 | 评估板 | - | 待定 |
| EVAL-AD7879EBZ | 量产 | 评估板 | - | 待定 |
- 民用温度范围：0 ºC～＋70 ºC
- 军用温度范围：－55ºC ～＋125ºC
- 工业用温度范围：不同型号的产品的温度范围可能不同。
- 汽车工作温度范围：-40 ℃～ +125 ℃
EVAL-AD7879EBZ 应用技术支持与电子电路设计开发资源下载
- AD7879 数据手册DataSheet下载 . pdf
- Analog Devices, Inc.ADI 美国模拟器件公司产品订购手册 .pdf
- ADC模数转换器选型指南 . pdf
