OPEN REX - power the board from J2

[Luca82]

Hello,
I would like to power the Open Rex from the 5V present on J2 (pins 2 and 4). I know that the board is designed to power other boards FROM those pins and not to BE POWERED from J2.
I also knwo that I will loose the overvoltage protection granted by Q7. But, beside this, can I power the board from the 5V in J2 ?
Thanks a lot !

[robertferanec]

Yes, you can. Just be careful, I think the PMIC is very sensitive for overvoltage and it can by easily damaged if you go over it's MAX input voltage. That is the reason why we included the protection.

[Luca82]

Thanks a lot !

[saeid]

Dear All,

As I have been checking Open Rex board as reference board for my custom board, it is used a PMIC (MMPF0100NPAEP) as power section. The chip has I2C pins.
When do we need to use them (I2C) ?

If I am going to use this PMIC, Do I require to communicate with this chip ? Because into the schematic, it is mentioned it use for register configuration .
Please advice What shall I do if I use this chip as PMIC ?

[robertferanec]

We do not talk to PMIC. You can change some settings in PMIC registers which can then change for example output voltage, but we do not need this.

[saeid]

Thank you so much for your answer, So why it is connected to CPU ?
How can we make a power POWER SEQUENCING as open Rex schematic Page[29] ?

[robertferanec]

"Thank you so much for your answer, So why it is connected to CPU ?"
- in very low power application and if properly implemented you could for example lower core voltage for different frequencies etc.

"How can we make a power POWER SEQUENCING as open Rex schematic Page"
- Have a look at our other boards e.g. iMX6 Rex module. That is using individual regulators. Or you would like to use PMIC, but you are not sure how to program it? Here is more info about that: https://www.imx6rex.com/open-rex/sof...-socket-board/

[saeid]

Thank you so much for your help.
I went through the link and I understood how you configured the power sequence. I have some more questions:
Since I do not have access to PF programmer:
1. Would it be possible to configure the PMICin u-boot of CPU ?
2. Can I use a simple microcontroller to configure the PMIC via I2C bus ?
3. Based on what did you do power sequence of PMIC ? For instance, seq1: xx V, seq2:xx V

Thanks in advance dear Robert

[robertferanec]

1. Would it be possible to configure the PMICin u-boot of CPU ?
- PMIC has to be programmed to correct voltages and in correct power sequencing to be able to run uboot

2. Can I use a simple microcontroller to configure the PMIC via I2C bus ?
- you should be able to use a microcontroller or any I2C programmer (e.g. Aardvark I2C/SPI Host Adapter https://www.totalphase.com/products/aardvark-i2cspi/ ) to program the chip

3. Based on what did you do power sequence of PMIC ? For instance, seq1: xx V, seq2:xx V
- I do not remember exactly, but I believe it is based on reference design

[saeid]

Thanks dear Robert for your helpful information as usual. As I mentioned, I am going to design a PCB based on i.Mx6. This is my first experience in High Speed PCB.
Please give me your advice about these questions:
1.Do you recommend me to design the Power supply of my Board (PMIC PF0100) in a 2 or 4 layer PCB separately first to make sure about power sequence or design the whole of board (PMIC + CPU + DDR3) ?
2. Some of the PMIC part number,for instance, MMPF0100F0AEP has Pre-Programmed with “F0” Programming which they have a fixed power sequence. If I am not mistaken, NXP SABRE Board (i.MX 6Q) use this chip and its power sequence. They did not change “F0” Pre-Programmed.
Would it be possible to use this chip without any change in “F0” Pre-Programmed? Does not effect this power sequence to CPU and DDR3 and u-boot process ?
The below pictures show the power sequence of the NXP baord and datasheet power sequence


NXP SABRE Board :

1	2	3	5	6	8	9	10	11	12	13
ARMCORE	VDDSOC	DDR	EMMC SD3 NOR SATA LVDS MIPI mPCIe SENSORS	GPS TOUCH EXP HDR	ETH	CAM	GPS mPCIe IMX6 (VDDHIGH_IN)	CAM	AUDIO ACC CAM	USB HDMI LVDS1

Datasheet :

1	2	3	5	6	7	8	9	10	11	12	13
ARMCORE	VDDSOC	DDR	EMMC SD3 NOR SATA LVDS HDMI MIPI mPCIe SENSORS	GPS TOUCH EXP HDR	AUDIO CAM ACC	ETH	CAM	GPS mPCIe	CAM	IMX6 (VDDHIGH_IN)	USB HDMI LVDS1

[robertferanec]

1) Buy development kit from NXP, I do not rember, but I think we had this one (we have got it for free from NXP, maybe ask them): https://www.mouser.sk/ProductDetail/...zikM%2F3wbo%3D

2) We program PMIC (you can buy also a programmer - we also got it from NXP together with development kit). I do not remember exactly, but it was like a special socket or something: https://www.mouser.sk/Embedded-Solut...yword=MMPF0100

PS: I do not know if F0 can be used - I would have to check it the same way as you are doing.

[saeid]

Thank you so much dear Robert for your support.

I have checked the SABRE Board's power supply page (Page19) , PMIC part number that is used is MMPF0100F0AEP. I checked the PMIC datasheet and it has pre-programmed with F0 configuration. There is a table in the SABRE Board PMIC schematic about power-up sequence that it is not match with F0 configuration.

In the CPU datasheet( MCIMX6Q6AVT10AD) is recommended to VDD_SNVS_IN supply must be turned ON before any other power supply. It may be connected (shorted) with VDD_HIGH_IN before VDD_ARM_CAP, VDD_SOC_CAP but in SABRE Board VDD_ARM_CAP and VDD_SOC_CAP will turn on before VDD_HIGH_IN that is not make sense.
By the way, I have attached the picture that can shows the datasheet information and SABRE Board's power sequence table.

Please give me your opinion about it ?
Can I use this power-up sequence for my custom board ?

[robertferanec]

If you are not sure, maybe try to check this with NXP, they should be the most competent people to help you with this. Or maybe design your board the way, what you think could work with F0, but initially use the chips with your own firmware to test it.

Please, I am not working on iMX6 anymore and it would take me a lot of time to get back into it.

[saeid]

I really appropriate it dear Robert