TPS7A1601 / startup operation

Ryuji

Guru 20090 points

Other Parts Discussed in Thread: TPS7A1601EVM-046

Hello,

I have questions about TPS7A1601 startup operation.

VIn=50V

Vout=5V(default setting of EVM)

Iout = 0A( No load)

Please see the attached file as waveform.

8686.Start up of TPS7A1601.pdf

<Questions>
(1) Is this operation no problem ?

(2) Please let me know this operation mechanism.

If there is any application note, please let me know.

Best Regards,

Ryuji Asaka

over 10 years ago

0 Ryan Eslinger over 10 years ago

TI__Guru 55940 points

Hi Ryuji,

Would it be possible to provide a schematic? This will help in understanding what is occurring in your application.

Very Respectfully,

Ryan

0 Ryuji over 10 years ago in reply to Ryan Eslinger

Guru 20090 points

Hello Ryan san,

Schematic is same with TPS7A1601EVM-046.

If you neef more information, please let me know.

Best Regards,

Ryuji Asaka

0 Ryan Eslinger over 10 years ago in reply to Ryuji

TI__Guru 55940 points

Hi Ryuji san,

I am trying to replicate the waveforms. Did you make any modifications to the EVM? Also, what is the status of J5, J6? Is C3 populated?

Very Respectfully,

Ryan

0 Ryuji over 10 years ago in reply to Ryan Eslinger

Guru 20090 points

Hello Ryan san,

I checked customer's information.

----------------

-They didn't any modification to the EVM. All parts are same with EVM.

-C3 is not populated

-J5 is open

-J6 is short

-instruments

Programable Power Supply : TR6143 , Advantest

Oscilloscope : TDS3014C , Tektronix

Probe : P6139B , Tektronix

----------------

If you need more information please let me know.

Best Regards,

Ryuji Asaka

0 Ryan Eslinger over 10 years ago in reply to Ryuji

TI__Guru 55940 points

Hi Ryuji san,

I am unable to duplicate your waveform on the bench. I would suggest having the customer try a new EVM.

Very Respectfully,

Ryan

0 Ryuji over 10 years ago in reply to Ryan Eslinger

Guru 20090 points

Hello Ryan san,

Thank you for the checking. I will replace the EVM.

By the way, is my waveform abnormal?

Best Regards,

Ryuji Asaka

0 Ryan Eslinger over 10 years ago in reply to Ryuji

TI__Guru 55940 points

Hi Ryuji san,

Yes. Your waveform is unusual. Typical startup waveforms will look like Figure 13 in the datasheet and Figure 1 in the EVM's User's Guide.

Very Respectfully,

Ryan

0 Ryuji over 10 years ago in reply to Ryan Eslinger

Guru 20090 points

Hello Ryan san,

Thank you for the checking.

I will get the customer's EVM and check the customer's EVM.

And I will get the new EVM and test it too.

I will post again if I get new concern.

Best Regards,
Ryuji Asaka

0 Ryuji over 10 years ago in reply to Ryuji

Guru 20090 points

Hello Ryan san,

I get new inromation from the customer.

Could you please kindly let me know the customer usage is acceptable or not.

-EN is turned on from other power supply of Vin

Then , they input 50V by hot-plug.

Thus, their Vin tr is faster than Vout tr. (please see the attached file)

0020.Start up of TPS7A1601_20131022.pdf

I think that , cause of this 2 step start up sequence is current limit or refference voltage problem or device failure due to hot-plug.

Please kindly let me know the below.

1. Can we use TPS7A1601-EVM by hot plug ?

2. If Vin tr is fast, Vout seaqunce will be 2 step ?

If yes, please let me know the reason.

Best Regards,

Ryuji Asaka

0 Ryan Eslinger over 10 years ago in reply to Ryuji

TI__Guru 55940 points

Hi Ryuji san,

From your latest post it appears that the customer is supplying the EN pin with a voltage before Vin. This is not the way the device was designed to operate. Ven should be less than or equal to Vin at all times. Please see the page 5 of the datasheet (copied here for convenience).

Very Respectfully,

Ryan

0 Ryuji over 10 years ago in reply to Ryan Eslinger

Guru 20090 points

Hello Ryan san,

Thank you for the information.

I miss out this description... sorry.

I see Absolute maximum ratings only...

Best Regards,

Ryuji Asaka

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TPS7A1601 / startup operation