TPM MCGIRCLK is changing freqency in VLPR mode

[nobodyKnows]

Hello,

I choosed the MCGIRCLK as source for the TPM Module to generating a PWM. It seem this is working. But if I change from 48Mhz running mode to VLPR the frequency is around 15% slower.

Is it possbile to avoid this issue? Is it also possible to calibrate the internal RC?

Thank you and best regards

Maximilian

[xiangjun_rong]

Hi,

Can you tell me the part number you are using? for the TPM driving clock source, do you use internal 48MHz clock or 4MHz internal reference clock which slower 15% in VLPR mode?

BR

XiangJun Rong

[nobodyKnows]

Hello, I use the 4MHz IRC for TPM driving source. The part nummer is KL26Z256.

[xiangjun_rong · Accepted solution]

Hi, Maximilian

I have checked the data sheet of KL26, the requency deviation of internal reference clock
(fast clock) over temperature and voltage —factory trimmed at nominal VDD and 25 °C is +/-3% at most.

Regarding your issue, i suppose you do not trim it before you use it. The trim value from factory is saved in the address 0x0000_03FE(bit 4:1) for the 4MHz fast internal clock source, you have to read it from the address and write it to the FCTRIM bits in MCG_C4.

For detailed inf, pls refer to the section in RM of KL26:

4.3.1 Alternate non-volatile IRC user trim description

24.3.4 MCG Control 4 Register (MCG_C4)

Hope it can help you

BR

Xiangjun Rong