Using VLPS mode in KM34Z128CLL5

[hieuhoang]

Hello all, I want to make a lowpower with KM34Z128CLL5. I want to use VLPS mode and my current must be under 10uA (with SLCD module and wake up by LPTMR). I followed the instructions in AN4470 but my current could not be smaller than 80uA. My question is that how I can decrease in my product? My code is attached in active_LCD.c file

When i used "LLWU Periodical Wakeup Using LPTMR" in Kinetis-M Peripherial Bare-Metal Drivers R2.3.1, my debug window (debugger is PE micro with OpenSDA interface type) stopped working at "OSC32K_Disable ();". I have been trying to reset MCU and OSC32k module didn’t work properly. Neither do all peripheral use 32k osc (PLL, FLL, SLCD). PLL and FLL have still been working properly with internal reference and 8M oscilator. After that, I replaced another KM34Z128CLL5, everything was ok. However, when I ran this example code again, my OSC32k did not work. Why did this module not work?

I am looking forward to getting your helps.

Your sincerely!

Hieu

[Hui_Ma]

Hi Hieu,

MK34 datasheet shows VLPS mode power consumption data is only for MK34 chip, and all peripheral clocks is disabled.

For customer still let SLCD module continue working, that will add power consumption when chip in VLPS mode.

Customer can consider to use internal regulator instead of external resistor divider network, which will reduce the power consumption.

In general, after MK34 boot up, the OSC32K is enabled. When customer call  OSC32K_Disable() function to disable RTC Oscillator (OSC32K).

For the RTC General Purpose Data Register (RTC_GP_DATA_REG) [CFG0] bit will be reset to 0 (enable the oscillator).

If there without  a reset process, customer need to call OSC32K_Enable() function to enable the RTC Oscillator again.

Wish it helps.
best regards
Ma Hui

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[hieuhoang]

Hi Ma Hui

Thank for your help! Your information is very helpful. But I have tried resetting MCU many times, flashing new program. And i had this error while executing OSC32K_Enable();. Value of RTC_GP_DATA_REG was readed as 0xFFFF.

Hieu