TPS53319: TPS53319 can't start up.

george qiao

Part Number: TPS53319

Sir, we have used TPS53319 to create 5V and 3.3V power.Now our problem is that TPS53319 can't start up at all PCBA boards. The“EN”,"VREG" have rised, but the output voltage is only 0.6V(3.3V and 5V circuit).please help to analysize.

over 7 years ago

0 JohnTucker over 7 years ago

TI__Guru**** 191445 points

User,

Can you post some start up waveforms? Please include the switching node.

0 JohnTucker over 7 years ago in reply to JohnTucker

TI__Guru**** 191445 points

User, the first obvious thing is your VREG / PGOOD connection. The capacitor should be directly from VREG to GND and the 100 k pull upshould be fro VREG to PGOOD. You have the pull up between VREG and the capacitor. Let me know if fixing that solves your issue,

0 george qiao over 7 years ago

Prodigy 40 points

the VREG power niose is serious.

0 JohnTucker over 7 years ago in reply to george qiao

TI__Guru**** 191445 points

User,

Yes as I commented, you do not have VREG connected correctly...

0 george qiao over 7 years ago in reply to JohnTucker

Prodigy 40 points

Sir，I have reworked to fellow pictrue,it haven't voltage output. switching node 0 level(A point of picture), VBST's level（B point of picture）is 5V.

0 JohnTucker over 7 years ago in reply to george qiao

TI__Guru**** 191445 points

User,

Time to check everything. Can you verify that VIN, VDD, VREG and EN are at their proper levels?

0 JohnTucker over 7 years ago in reply to JohnTucker

TI__Guru**** 191445 points

User,

Then the next thing is to see if the circuit actually starts up, then shuts down, or if it never starts at all. You can trigger on VIN rising edge when power is applied and look at the switching node and Vout. Let us know what you find.

0 Henry Nguyen over 7 years ago in reply to george qiao

TI__Intellectual 2460 points

Hello,
I checked your schematic above. You used the ROVP (pin #5) feature. This feature is described on page 17. If you don't want to use this feature, just need to ground pin #5. If you want to use this feature, the resistor divider ratio needs to be the same as output resistor divider ratio (similar to the user guide schematic).
Try to ground pin #5 to see whether it can start-up.
Kit

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TPS53319: TPS53319 can't start up.