S9KEAZN64AMLC microcontroller power management behaviour

[Muthusankar]

We are using S9KEAZN64AMLC microcontroller for our project.
We are performing below usecases for electrical stability testing.
1. Kept the Supply voltage as 12V - MCU is ON and running.
2. Reduce the supply voltage to 2V.
3. Increase the supply voltage 2 - 3 V and kept the 3 voltage for 10 sec.
4. Increase the supply voltage to 3 - 4 V and kept 4 V for 10 sec.
5. Same way increase the voltage step by step till 12 V.
Expectation :
1. MCU should come to normal mode and perform all the functionality.
Actual:
1. MCU is not comes to normal mode if we increase the supply voltage step by step with specific sequence.
2.Enable the Low Voltage Detection Citcuit and Kept configuration as Low trip point is selected -
PMC_SPMSC2 VLVW = VLVW1.
3. If we increase the supply voltage faster or continously (Without 10 sec break), MCU is working
fine.
Please find the Reset Line waveform in the attachment.
Our Quries:
1. Any Idea Why MCU is not comes to normal mode, if we increase the voltage slow sequence(step by step).?
2.Attached waveform is right sequence for the MCU during supply voltage variation from 2 to 12 V?

[xiangjun_rong]

Hi,

I suppose that the VDD and VDDA power supply operating voltage is from 2.7V to 5.5V, the limiting voltage of VDD is 6V, do you impress 12V DC voltage on the VDD pin?

Pls download the data sheet of S9KEAZN64AMLC from the link:

https://www.nxp.com.cn/docs/en/data-sheet/S9KEA64P64M20SF0.pdf

BR

XiangJun Rong

[Muthusankar]

Hi XiangJun Rong,

Thanks a lot for the response,

We are using the LDO to give constant supply to the MCU.

Battery Supply is connected to LDO and LDO ouput is connected to MCU-VDD pin.

LDO Part number - BD450M2EFJ-CE2

Atttached the LDO Circuit , MCU Connection in schematic and Data sheet of LDO.

Summarizing the Quries:
1. Any Idea Why MCU is not comes to normal mode, if we increase the voltage slow sequence(step by step).? 
2.Attached waveform is right sequence for the MCU during supply voltage variation from 2 to 12 V?

3.Can you please provide how the MCU-PMU will behave during the sequence mentioned in the first comment.?

4. Is there specific configuration we have to do in MCU-PMU module ?

Thanks,

Muthu

[xiangjun_rong]

Hi,

The S9KEAZN64AMLC has LVD module, which can detect the VDD voltage and generate interrupt or Reset event once the VDD voltage is less than a threshold.

When the chip is in Reset state by the LVD module, after you rise the VDD to an operating voltage, the Reset will be deasserted and the chip can run.

For detailed inf, pls refer to section 13.2 Low voltage detect (LVD) system in the KEA64RM.pdf

BR

XiangJun Rong