EM2130 boot up problems

[RBach6]

Hello,

we are using em2130L and em2130H to generate 0.9 and 3.3 V respectively and used the schematic from cyclone 10GX eval board. one thing we missed was instead of 1206 package 22uf cap, we used 0603 package 22uf cap. Output of 2130L is 0 when not enabled, and goes to some value between 0.4 and 0.6 when we turn the regulator on by making the contrl pin high. When we probe pwm signal, we see pulses for about 3 ms and they stop.Output of 2130H is stuck at .632 v all the time with or without making the control pin high. What could be the issue here? Is the input really dependent on using 22 uF 1206 size caps? It would be helpful, if someone can throw some light on it

Thanks,

Ramakrishna

[Mostafa_Intel_AE]

Hello Ramakrishna,

Probably you maybe facing an instability issue or your design trigger the OCP.

Are the PMBUS/I2C is enabled on your design, so we can connect Enpirion dongle and check with the GUI what is the fault there?

Also if it possible to share your schematic and layout for EM2120 and EM2130 so i can review your design.

I will send you an personal email so you can share your files through.

Regards,

Mostafa

[RBach6]

Hi Mostafa,

thanks for your reply. We replaced 2.2uf caps with 22uF caps (we will switch to 1206 package in the next revision).

We found the problem being RTUNE set to the wrong value. We copied the schematic from the cyclone 10gx eval board EM2130L which has base capacitance of 860 uF and RTUNE of 6.04k ohm. According to the datasheet for this base capacitance RTUNE should have been 1.5k ohm. Once we changed this, 0.9V regulator has been good. We made a mistake with the BOM for EM2130H. we populated 3.3V with EM2130L and no wonder it is not working. Local assembly house replaced the part and it has been intermittent(works though). My question is, is there a better way to replace these parts if they go bad after assembling the whole board. Local board house can't guarantee the functionality, if they swap only this part on the board. Is there a temperature profile or a preferred method/vendor you recommend for swapping these parts as it doesn't make sense to trash an expensive board for a $30 regulator, and by the way they work great once everything is set up right

Thanks,

Ramakrishna

[Mostafa_Intel_AE]

Hi Ramakrishna,

Sorry for late response, i was off last week.

This is good news.

Regarding the assembly issue EM2130H instead of EM2130L, can i know how many board have that issue and need to do the rework.

Also could you please share your schematic and let me know if you have the connection for SDA/SCL signal, so we can reprogram the part manually to allow EM2130H to work as EM2130L, it is not easy to do but if you only have 1 or 2 boards with that issue i can help to reprogram it.

Regards,

Mostafa

[Mostafa_Intel_AE]

Hi Ramakrishna,

Do you have any updates?

Regards,

Mostafa

[RBach6]

Hi Mostafa,

sorry for the delayed response. I am still on vacation, but I can describe what went on with our boards

board 1

em2130L was installed for both 0.9 and 3.3 V with 22uf(0603) caps on input +12V. This board doesn’t have C10gx installed on the board. Local board house replaced em2130L with em2130H. em2130L worked fine, but we had to physically push em2130H to work and it was working ok

board2

it is exactly the same as board 1, but with c10gx installed. It worked for a day and we had pretty good success with em2130L and em2130H. It was working fine even after we connected an fmc board with adcs and dacs. It stopped (em2130H)working all of a sudden. I connected the pmbus, but it also hangs up

i need information on two things

1.how critical is the cap case size on the input? Datasheet says 1206, 22uf but we have 0603

2.is there an assembly house that can reliably swap em2130 chips on stuffed boards

i don’t want to trash a $2000 board if something goes wrong with $30 part. Please let me know

thanks,

Ramakrishna

[Mostafa_Intel_AE]

Hi Ramakrishna,

I still have a concern about your system stability, if you could share your schematic and show if you have any decoupling capacitors attached to EM2130L and EM2130H, so i can calculate the correct Rtune.

The input capacitor is important to reduce the noise on the 12V rail and that capacitor should have a voltage rated at least 1.5 times of the rail voltage which mean 1.5x12=18V, and i don't think 22uF/0603 will have that voltage rate.

If your 22uF/0603 input capacitor has low voltage rate than 18V, this will put a lot of stress on it and will be damaged after some time.

So you need to check if that capacitor still ok or it is already damaged, please check the input impedance Pvin to PGND.

Regarding replacing EM2130L with EM2130H, please let me know how many board you have that need to swap EM2130L by EM2130H.

The easiest way to solve that issue is to make EM2130L generate 3.3V by changing R1DIV to 2K , R2Div to 1K and RVSET to 4.22K.

Rtune also needs to be adjusted, but i need to know what is the capacitors part number you are using and how many of them.

Regards,

Mostafa

[RBach6]

Hi Mostafa,

unfortunately I don’t have the schematic with me. 22 uf, 0603 capacitors are rated at 16V and the 0.9 V regulator works fine as it was stuffed at the assembly house.em2130L which was wrongly installed was swapped out at the local assembly house(I should have waited for your response before swapping those) and because of the complexity they couldn’t guarantee the installation.we adjusted the Rtune to match with the output capacitance. That’s when both 0.9V and 3.3V worked. Our problem is are there any instructions or assembly houses that can swap these parts? I will email you the schematic once i get back from vacation on 29th.we will switch to 1206 caps in the next revision, but i would like to test the board completely before next revision. That’s the reason, I would like to replace the part reliably. Please let me know, if you have any suggestions.

thanks,

Ramakrishna

[Mostafa_Intel_AE]

Hi Ramakrishna,

I just sent an email to you with the PCB house information.

Please check with them, where they probably will be able to do the EM2130 replacement.

Regards,

Mostafa