Kinetis KL05 internal oscillator precision

[atwoz]

Hello,

I couldn't find in the datasheet or in the manual the precision of the internal oscillator. In other Microcontrollers it ranges from 0.9% to 3% from what I've seen. Does anyone know the precision of the Kinetis L series internal oscillator?

I need to know to decide whether I should use an external crystal or not for UART communication.

Thanks.

[LuisCasado · Accepted solution]

Hello,

It is in the datasheet, Table 11

http://cache.freescale.com/files/32bit/doc/data_sheet/KL04P48M48SF1.pdf?fpsp=1&WT_TYPE=Data Sheets&WT_VENDOR=FREESCALE&WT_FILE_FORMAT=pdf&WT_ASSET=Documentation

Luis

[atwoz]

So, 3% error worst case? Thanks Luis

[LuisCasado]

Hi,

Yes, +-3% worse case, full range of temperature and voltage operation.

You can improve the influence of the temperatura with the internal temperature sensor to compensate the frequency variation, but you would have to create your own table at the voltage of operation.

Best Regards,

Luis

[atwoz]

Hello Luis,

I have one last question. Looking at table 12 I see the current consumption especification for different frequencies. Are those for external crystal oscillators too? If I have an 8Mhz external crystal in high power mode (HGO=1) will my clocking current consumption be 500uA?

I'm trying to figure out the best way to configure a low power application that will requiere UART.

Thank you!

[LuisCasado]

Hi Arturo,

In the Table 5 you have the power consumption for the different modes of operation of MCU. And in the table 6 you have the adders for any peripheral/system you have on in that particular mode (if you can have on the peripheral in that particular mode of operation). Table 6 inlcudes the internal oscillator adders, table 12 the external ones.

Ceheck the KL25 SC code:

http://cache.freescale.com/files/32bit/software/KL25_SC.exe?fpsp=1&WT_TYPE=BSDL&WT_VENDOR=FREESCALE&...

The example klxx-sc-baremetal\build\cw\low_power_dma_uart_demo is the one you need, Kinetis L has the low power UART and can work with DMA without CPU intervenction.

Regards,

Luis

[atwoz]

Excellent! Thank you Luis!