Details of Power down sequence of STM32N657X0H3Q

[Tejas_P_R]

Hi All, In datasheet of STM32N657X0H3Q controller only power-up sequencing details are shown., Is there any power down sequencing is required?

If Yes, Please suggest the document which gives complete information of power down sequencing. 

[RomainR.]

Hello @Tejas_P_R 

For the power-up conditions, proceed in this order: 1, 2 and 3.

1. Apply VDD and VDD18AON (VBAT connected to VDD if no external battery is used), this will give the output PWR_ON=1.
2. Apply VDDCore (in external SMPS bypass using PWR_ON) and VDDSMPS  in internal SMPS.
3. Then apply the other supply: VDDA18PLL, VDDIOx, VDDA18PMU, VDDA33USB, VDDA18USB, VDD33USBCC, VDDCSI, VDDA18ADC, VREF+

For the Power-down, follow the procedure in reverse order 3, 2 and 1.

Best regards,
Romain,

[Tejas_P_R]

Hi Romain,

Thanks for your reply...!

We will follow the power-up sequence as mentioned in datasheet, But If we are not going to use the power down sequencing and turning OFF all power supply at once will affect any functionality?

Regards

Tejas

[RomainR.]

@Tejas_P_R 

In this case, you do not proceed with a power-down sequence, but with a complete direct shutdown.
This will not cause any problem.

Best regards,

Romain,

[Yigitkilicli]

Hello @RomainR.

I need a help with a similar problem. In my custom design, I am using similar regulators and, connections as your development kit. 

1) I apply VDD and VDD18AON voltages at the same time. 

2) I get PWR_ON=0. I wait for PWR_ON  to be high, to enable other voltages. But it doesn't turn on high.

3) When I touch the PWOR_On pin with multimeter to measure voltage PWR_ON pin, it becomes high.

Eventualy the uC doesn't run.

Could you please advice me on this problem

Best Regards.

[RomainR.]

Hi @Yigitkilicli 

If it is related to a custom design, check your pcb and gerber. I suggest to check if all VDD balls are correctly connected to VDD depending of the package you are using. Same for the unique VDDA18AON and all VSS.

Refer to DS14791 in the Table 18 to check which package balls for VDD are used:

In second time, can you get a oscilloscope capture of VDD and VDD18AON rising ?

Best regards,

Romain,

[Yigitkilicli]

@RomainR.  Hello again,

 First of all, thank you for your help.

2) I checked two times. My pcb design, STM32N657X0H3Q footprint and schematic. But I can not found any fail. Because of I copy stm32n6 disco board schematic and I used 14mmx14mm same footprint uC.

2) The red line 3v3 VDDIO and the yellow line is VDD18AON. My scope 100us/div. In additionally, I used same regulator with stm32n6 disco board.LD39020ADTPU33R and LD39020ADTPU18R.