TPS65265: DC DC doesn't start automatically

Yosy Shmuly85

Part Number: TPS65265

on my board the TPS65265 is configured with MODE = '0' EN1 = '0' EN2 = '1' and EN3 controlled by GPIO, so there is a power-up sequence after EN3 is enabled

after power up nothing is coming out of the three outputs

when changing the strapping to MODE = 'Float' EN1 = '1' EN2 = '1' and EN3 = '1' by resistors the TPS65265 is working properly

did I miss anything?

see attached schematics for more details

over 7 years ago

0 Jason Wang (BSR-MV) over 7 years ago

TI__Genius 9550 points

hi,

Do another test: leave R1000 and R1001 floating(pull high via IC internal circuit). check if the power up correct?

My analysis about this phenomenon: EN2 trig high (1.15V typically) is later than EN3 trig high.

Jason Wang

0 Yosy Shmuly85 over 7 years ago in reply to Jason Wang (BSR-MV)

Prodigy 155 points

EN3 is driven from a GPIO expander so it is actually trig long after E1 E2 and MOD are set

so thgis try didnt work for me

Eventually I succeeded operating the BUCK using smaller values of resistors:

pull-downs replaced from 33k to 1.5k

pull-ups replaced from 100k to 3k

with this value of resistors a high state on EN2 is also captured when left floating

0 Jason Wang (BSR-MV) over 7 years ago in reply to Yosy Shmuly85

TI__Genius 9550 points

good news that you solved this issue in your side.

by the way, did you try the test which i mentioned?( remove R1000 and R1001), also please confirm if C828 on board? if yes, remove it.

0 Yosy Shmuly85 over 7 years ago in reply to Jason Wang (BSR-MV)

Prodigy 155 points

I did try it, but it didn't work with the high val res, C828 is not assembled
EN3 is driven from GPIO expander (not open drain but actual drive) is it ok?

0 Jason Wang (BSR-MV) over 7 years ago in reply to Yosy Shmuly85

TI__Genius 9550 points

yes, it is ok to use GPIO expander (not open drain)

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TPS65265: DC DC doesn't start automatically