针对DCO利用外部电阻产生时钟模式下,可以通过ROSC管脚连接一个外部高精度电阻,如原文所示:When DCOR bit is set to 1 by the application, the DCO selects the external resistor mode for operation. It is recommended to connect a 20-kΩ 0.1% ±50-ppm/°C resistor at the ROSC pin of the device for operating in the external resistor mode. This mode offers higher clock accuracy in terms of absolute tolerance and temperature drift compared to internal resistor mode.
但是文中并没有对于此高精度电阻的特性给以明确说明,是用金属膜电阻还是碳膜电阻。同时对于电阻的封装形式有没有一个规定。比如最小得多大的封装。等等。对于不同特性电阻(精度相同,温漂特性相同的条件下)连接下,所产生的时钟的区别有多大? |