TPS65217C connected to AM335x getting shutdown in some boards

Rohit Prajapati

Prodigy 180 points

dear sir,

In my design we are using AM335x processor and TPS65217C Pmic.

in second proto of my design some boards have power issue problem.

SYS_Voltage getting down to 1.5-2.5 voltage in with in 500ms. i have checked all signal with respect to sys_voltage.

my observation was that power_en & ldo1 follows sys_volt.

sys volt goes down first and then power_en , ldo1 , PGOOD , LDOPGOOD goes down .

pmic configuration as per below ckt.

please suggest any sollution for this design issue.

over 12 years ago

0 Biser Gatchev-XID over 12 years ago

TI__Guru**** 393215 points

Where is the "below ckt"?

0 Rohit Prajapati over 12 years ago in reply to Biser Gatchev-XID

Prodigy 180 points

0 Biser Gatchev-XID over 12 years ago in reply to Rohit Prajapati

TI__Guru**** 393215 points

It's not visible again. Try inserting the file in your comments.

0 Rohit Prajapati over 12 years ago in reply to Biser Gatchev-XID

Prodigy 180 points

0 Rohit Prajapati over 12 years ago in reply to Rohit Prajapati

Prodigy 180 points

0 Biser Gatchev-XID over 12 years ago in reply to Rohit Prajapati

TI__Guru**** 393215 points

Hi Rohit,

R21, R36, L3, R252 and R254 are unnecessary and should be removed. VIO should be tied to LDO1 output, not to 3.3V. Check the Beaglebone Black schematics for reference: http://circuitco.com/support/index.php?title=BeagleBoneBlack#LATEST_PRODUCTION_FILES_.28A5C.29

0 Rohit Prajapati over 12 years ago in reply to Biser Gatchev-XID

Prodigy 180 points

Hello Biser ,

Thank you for your reply.

i have tried with your suggestion in one of the board but there was no improvement in sys voltage , still it at 1.5V.

this issue occurs in some of the boards of total i have , and other are working fine with same design attached.

in one case i have replaced PMIC with new one , it working for first power up , then in second power reset sequence same issue sys voltage down....

please suggest me any possibilities...

thanks and regards,

Rohit Prajapati

0 Biser Gatchev-XID over 12 years ago in reply to Rohit Prajapati

TI__Guru**** 393215 points

Hi Rohit,

Check your input voltage on the failing units. Voltage on AC pin must be <5.8V, on BAT must be <5.5V.

0 Rohit Prajapati over 12 years ago in reply to Biser Gatchev-XID

Prodigy 180 points

HI Biser ,

We have checked both the voltages it is stable AC i/p is 5.2Vmax

And BAT voltage is below 3.7V

Is there any chances, sys boot config line makes microprocessor in floating state & because of that it load all the voltages & it makes SYS_VOL low

Our sysboot lines are multiplexed with other peripherals

We observed From our working board also some of the board not working some times, it gives "CCCCCC" initially and when its try to shift to NAND that time sys voltage becomes 2.2V or something and it stays there and some times its goes direct to 2.2 volt without giving "CCCCCC".

Thanks,

Rohit

0 Biser Gatchev-XID over 12 years ago in reply to Rohit Prajapati

TI__Guru**** 393215 points

I can't say much without having the schematics, but it may be that you get an overload on one or more voltage rails. What I can recommend is that you check your schematics against the http://processors.wiki.ti.com/index.php/AM335x_Schematic_Checklist. You can also check the reference design schematics that can be found here: http://processors.wiki.ti.com/index.php/AM335xBoards.

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TPS65217C connected to AM335x getting shutdown in some boards