The AD7877 is a 12-bit, successive approximation ADC with a synchronous serial interface and low on resistance switches for driving touch screens. The AD7877 operates from a single 2.7 V to 5.25 V power supply (functional operation to 2.2 V), and features throughput rates of 125 kSPS. The AD7877 features direct battery measurement on two inputs, temperature and touch-pressure measurement.
The AD7877 also has an on-board reference of 2.5 V. When not in use, it can be shut down to conserve power. An external reference can also be applied and varied from 1 V to +VCC, with an analog input range of 0 V to VREF. The device includes a shutdown mode that reduces its current consumption to less than 1 µA.
To reduce the effects of noise from LCDs, the acquisition phase of the on-board ADC is controlled via the STOPACQ pin. User-programmable conversion controls include variable acquisition time and first conversion delay. Up to 16 averages can be taken per conversion. There is also an on-board DAC for LCD back-light or contrast control. The AD7877 runs in either slave or master mode using a conversion sequencer and timer. It is ideal for battery-powered systems such as personal digital assistants with resistive touch screens and other portable equipment.
The part is available in a 32-lead lead frame chip scale package (LFCSP), and a 25-ball wafer level chip scale package (WLCSP).
AD7877是一款12位逐次逼近型ADC,具有同步串行接口以及用于驱动触摸屏的低导通电阻开关,采用2.7 V至5.25 V单电源供电（2.2 V也可正常运转）,吞吐量为125 kSPS。AD7877可用于两个输入上的电池测量、温度测量和触摸压力测量。
AD7877还具有一个2.5 V片上基准电压源。不使用时,可关断基准电压源以降低功耗。也可以使用外部基准电压,并可在1 V至+VCC范围内变化,模拟输入范围为0 V至VREF。这款器件具有关断模式,此模式下功耗不足1 µA。
片上ADC的相位采集通过STOPACQ引脚来控制,这样可以降低来自LCD的噪声影响。用户可编程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。该器件还有一个片上DAC,用来控制LCD背光或对比度。AD7877采用转换序列器与定时器,可在从模式或主模式下工作,非常适用于电池供电系统,如带电阻触摸屏的个人数字助理及其它便携式设备。
该器件提供两种封装：32引脚架构芯片级封装（LFCSP）和25引脚晶圆级芯片规模封装（WLCSP）。
| 产品型号 | 产品状态 | 封装 | 引脚 | 温度范围 |
|---|---|---|---|---|
| AD7877ACBZ-REEL | 量产 | 25 Ball WLCSP | 25 | 工业 |
| AD7877ACBZ-REEL7 | 量产 | 25 Ball WLCSP | 25 | 工业 |
| AD7877ACP-500RL7 | 量产 | 32 ld LFCSP (5x5mm CP-32-2) | 32 | 工业 |
| AD7877ACP-REEL7 | 量产 | 32 ld LFCSP (5x5mm CP-32-2) | 32 | 工业 |
| AD7877ACPZ-500RL7 | 量产 | 32 ld LFCSP (5x5mm CP-32-2) | 32 | 工业 |
| AD7877ACPZ-REEL | 量产 | 32 ld LFCSP (5x5mm CP-32-2) | 32 | 工业 |
| AD7877ACPZ-REEL7 | 量产 | 32 ld LFCSP (5x5mm CP-32-2) | 32 | 工业 |
| EVAL-AD7877EBZ | 量产 | 评估板 | - | 待定 |
