TPS65145: I based a design off of the DLPC7540EVM, and the TPS65145 doesn't always startup properly

Paul Sluis

Part Number: TPS65145
Other Parts Discussed in Thread: DLPC7540EVM, DLP650TEEVM

In my design I implemented the voltage Tripler configuration as per the reference design, and the 16V supply goes to 18.5V. When I make the correction to set the board as a voltage doubler it correctly regulates to 16V - sometimes. Most of the time however, the TPS65145 does not startup properly, and sits at some mid point voltage ~4V.

Questions:

1) Why does the reference design have the TPS65145 setup as a voltage Tripler on the DLPC7540EVM?

2) Any ideas why the TPS65145 mostly does not startup correctly?

3) What is the purpose of the NFET (Q502) in reference design?

Thanks,

Paul

SCH-00081_R1 SCH DLP651 DMD INTERFACE.pdf DLP057A-002_DLP650TEEVM_SCH.pdf

over 1 year ago

0 Tristan Bottone over 1 year ago

TI__Intellectual 800 points

Hello Paul,

Thanks for reaching out and using the E2E Forums! I have assigned this thread to someone more familiar with this platform. We will review this thread and get back to you shortly.

0 made4engineering over 1 year ago

TI__Mastermind 27460 points

Hi Paul,

To ensure the power sequencing is within datasheet specs we have Q502 to control the startup of VBIAS, and you should have this for correct operation

_Aaron

0 Paul Sluis over 1 year ago in reply to made4engineering

Prodigy 240 points

Hi AAron,

Ok. Thanks for the info. However, I have already established that the voltage Tripler configuration doesn't work correctly (it goes to 18.5V). When I set it as a voltage doubler it works correctly, but how should I connect the external FET Q502 in the voltage doubler configuration?

Thanks,

Paul

+1 made4engineering over 1 year ago in reply to Paul Sluis

TI__Mastermind 27460 points

Hi Paul, connect it like in our reference design. Also double check the feedback resistors (in green) are the correct values

Power management

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TPS65145: I based a design off of the DLPC7540EVM, and the TPS65145 doesn't always startup properly