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Part Number: TPS54290
Hi, We are using TPS54290 in our design and using it as Dual output source ( 1.8V and 3.7V respectively) .
PVDD1 and PVDD2 are shorted and fed by 12V supply.
Default EN1 and EN2 are pulled down.
After turning on input PVDD1=PVDD2 = 12V . We are getting Out 1 around 1.48-1.9V on 5 boards we tested( should be 1.8V as R1 /R2 at FB1 are 20K/16K) .
But major issue issue is with Out 2 . we are getting around 1.77V - 2V range on 5 boards we tested. (should be 3.7V as R1 /R2 at FB2 are 33K/9.1K) .)
Is there any sequencing required for EN1 and En2 ( EN2 should come before EN1) in case when we have PVDD1 and PVDD2 tied together?
In reply to BHUPENDAR SINGH:
BSR-CCP LV/MV DC/DC Applications
In reply to JohnTucker:
I am pleased that my recommendation worked. Sometimes power supply design is a mixture of both science and art as I did not use any equations to design the compensation network. I don't see your attachment. If you can provide it I may be able to give you some feed back.
0743.slum164 (4) - autosave 17-12-07 10_55.TSC8473.DC_DC_Buck Regulator_Components_Calculations_updated.xlsxSorry i didn't mentioned correctly, it was attached in one of my previous reply. I am attaching it again here.
Yes with the value you provided, it is working. But we wanted to know where we went wrong in calculating the compensation network components values and how these values arrives.
It will be really helpful if you can go through the excel and see if we did something wrong. We couldn't find it from our end . And if we leave it now, it can again be repeated in future design too if not corrected.
Thanks & Regards,
I have reviewed the spreadsheet you sent. It had an invalid character in the file name that prevented me from opening it, but renaming fixed that. I went thru every calculation in detail and did not find any errors. I also used the resulting component values in pspice. Pspice predicts output 1, Fco = 57 kHz, PM 36 deg. Output 2, Fco = 68 kHz, PM = 13 deg. Both of those are low especially output 2. As I may have stated previously, we inherited support for TPS54290 from another group, so I do not know who derived those compensation equations and spreadsheet. They most likely work well for some scenarios, but not for your case. I will note this issue to our management to see if someone can be assigned to update it.
Appreciate your support on this issue.
It will be great if you can route us to the right contact who can help us to find the right way to calculate compensation values for TPS54290.
In reply to David Urban:
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