描述：超小的USB转TTL模块 选择无需外部晶振额CH340C 为了可扩展为自动烧录模块没有选择EN系列芯片 PCB尺寸仅 2.3CM长 1CM宽 宽度已经是芯片宽度无法更小了 可为51 Arduino

该文档为STC单片机USB下载器原理图-USB转TTL讲解文档，是一份不错的参考资料，感兴趣的可以下载看看，，，，，，，，，，，，，，，，，

从一个原理图里拆出来的usb转TTL的原理图，使用的usb芯片是ch340g

These positive-edge triggered flip-flops utilize TTL circuitry to
implement D-type flip-flop l

This device contains four independent gates each of which
performs the logic NAND function. Ea

This device contains four independent gates each of which
performs the logic NAND function. Th

These positive-edge triggered flip-flops utilize TTL circuitry
to implement D-type flip-flop l

This device contains four independent gates with two data
inputs, each which performs the logi