TPS2592AL Power up issue

Mac Chen

Intellectual 590 points

Other Parts Discussed in Thread: TPS2592AL

Hi,

I have a system design with TPS2592AL. Currently, I have a issue when the power up.

The Condition are

Vin= 12V, UVP setting =9V, Rlim=143K, dv/dv= floating, BFET=floating,

Cout is ~220uF

Usually, I can get all function work.

but few times, the Vout will be ~ 7 to 8V, then Vout ramp up very slowly.

Does anyone know this issue, and how to clarify this ?

Thanks !

Mac.

over 9 years ago

0 Darwin Fernandez over 9 years ago

TI__Mastermind 40385 points

Hi Mac,
I recommend first looking into the design calaculator in the product page of the TPS2592AL to catch any initial design issues. Next, be sure the the output ramp rate and Rlim is designed such that it does not hit thermal shutdown (depending on whether the output is loaded or not) as descibed in the datasheet.

0 Mac Chen over 9 years ago in reply to Darwin Fernandez

Intellectual 590 points

Hi Drawin,

My loading is around 80mA.

I'm not sure, if dv/dt is floating.

Does it limit the inrush current when the power up ?

0 Dinesh Kumar6 over 9 years ago in reply to Mac Chen

TI__Intellectual 2980 points

Hello Mac,

Could you please share your full design specifications and schematic with us?

Best regards

Dinesh

0 Mac Chen over 9 years ago in reply to Dinesh Kumar6

Intellectual 590 points

Hi Dinesh,

pls check the links.

this is my design with the webench online tool. If I got something wrong, pls let me know.

http://drp.io/QkMfGscee

Behind this, it will have others capacitor and device, so the total cap. for TPS2592AL Cout will around 200uF.

I just test Iout less 100mA, and sometimes I will get the issue. It's weird, so I need someone could clarify for me.

Thanks !

Mac.

0 Dinesh Kumar6 over 9 years ago in reply to Mac Chen

TI__Intellectual 2980 points

Hello Mac,

Thanks for sharing the link but I am uable to open this as it is blocked by TI network.

Please attached the pdf of the schematic will review and suggest steps.

Regards

Dinesh

0 Mac Chen over 9 years ago in reply to Dinesh Kumar6

Intellectual 590 points

Hi Dinesh,

How can I send the PDF to you?
Cloud you provide me your email add?

0 Dinesh Kumar6 over 9 years ago in reply to Mac Chen

TI__Intellectual 2980 points

Mac,

You can attached the schematic in the post using the insert file option above.

Regards

Dinesh

0 Mac Chen over 9 years ago in reply to Dinesh Kumar6

Intellectual 590 points

Hi Dinesh,

The schematic is as below.

Thanks !

Mac.

0 Mac Chen over 9 years ago in reply to Mac Chen

Intellectual 590 points

Hi Dinesh,

I measured the failure Vout function ~7.5V, and the dv/dt is ~1.5V. (normal IC, it's 2.4V )

Does it have the issue could cause dv/dt drop down ?

The datasheet mentions BFET discharge function. Does it effect the dv/dt, and I got the Vout result around ~7.5V.

Mac.

0 Dinesh Kumar6 over 9 years ago in reply to Mac Chen

TI__Intellectual 2980 points

Hello Mac,

Please share the schematic and failure waveform of you design.

Then I can comment on what is happening.

Regards

Dinesh

0 Dinesh Kumar6 over 9 years ago in reply to Mac Chen

TI__Intellectual 2980 points

Hello Mac,
I saw your schematic above.
4A current limit is not recommend with this device.
Also when your load is only 80mA, why did you set the current limit to 4A.
Regards
Dinesh

0 Mac Chen over 9 years ago in reply to Dinesh Kumar6

Intellectual 590 points

Hi Dinesh,

My load is not only 80mA, I have a power sequence in this design. If all blocks work, the load will be 2~3A.

However, I doesn't let my other functions work, and I just test about the TPS2592AL, and got this weird function back.

Mac.

Power management

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TPS2592AL Power up issue