Maxim MAX1441汽车遥控钥匙解决方案

Maxim公司的MAX1441是接近式和触摸传感器IC,14V的工作电流只有100uA, 1.2fF LSB电容/数字分辨率,工作电压5V-28V,45V过压保护,2k字闪存,128B SRAM,传感器I/O线±2kV ESD保护,JTAG接口,支持两个单独接地电容传感器输入.主要用在无源遥控钥匙(PRKE)系统接近传感和物件检测系统.本文介绍了MAX1441主要特性,方框图, 典型应用电路图以及MAX1441评估板主要特性,电路图,材料清单和PCB布局图.
The MAX1441 proximity and touch sensor IC is designed for capacitive proximity sensing in automotive passive remote keyless entry (PRKE) and other applications. This device provides signal processing to support two independent touch/proximity sensor channels. The device features two open-drain output pins with high-voltage capability up to 28V, as well as five digital I/Os to indicate sensing events. During manufacturing, JTAG programming uses four digital I/Os.
The device uses grounded electrode capacitive sens­ing to measure capacitance between one of the two sense pins and the ground. A hand approaching a sense electrode attached to these sense pins causes a change in measured capacitance indicating the presence (touch or proximity) of the object. Active-guard outputs shield the sense electrode from unwant­ed sources without adding parasitic capacitance. Spread-spectrum techniques in the sensor excitation circuit reduce both electromagnetic emissions and susceptibility to interfering signals. In addition, the sensing excitation frequency is programmable from 100kHz to 500kHz in 10kHz steps to avoid interference.
The sensor input signals are converted to a 12-bit digital data and are available to an on-chip microcon­troller (FC). The device provides independent offset compensation of up to 63pF for each input channel. Each channel can be programmed to 5pF, 10pF, or 20pF full-scale range.
The device features an internal MAXQ® microcontroller with 2kword of flash for user programs and 128 bytes of SRAM. This feature provides the ability to implement customized signal processing and di...