C8051F9xx Current Consumption with 24.5 MHz Precision Oscillator

by <a href="http://community.silabs.com/t5/Welcome-and-Announcements/Community-Ranking-System-and-Recognition-Program/m-p/140490#U140490"><font color="#000000"><font size="2">Ninja Employee</font></font> </a> marao on ‎03-30-2017 07:10 PM

Question

Why do I see higher current consumption than your data sheet claims when I operate the device from the 24.5 MHz precision oscillator?

Answer

There are two common reasons for this.

 

First, check to make sure that you are not driving the system clock (or any other clock) out on a GPIO pin. A 15 pF load that is switched at 24.5 MHz will consume more than 1 mA from a 3-volt supply.

 

Second, make sure that the Flash one-shot timer is disabled whenever the SYSCLK frequency is greater than 10 MHz; failing to do so can add between 1-2 mA to the chip current consumption.