TPS62811-Q1: Track function

nia sun

Part Number: TPS62811-Q1
Other Parts Discussed in Thread: TPS22919

Tool/software:

Hi, there~

I manage to use TPS628112 and a HSW IC TPS22919 to achieve track function, that is according to TPS628112's SS/TR pin function.

Add external voltage on this pin and make sure external voltage slightly bigger than internal reference voltage (0.6V).

It doesn't work well, so I make a little test, chang 4.7k resistor to 470ohm resistor,that expect DSP_1.8V output follow outside voltage tightly, and output 0.25V.

no it doesn't. The picture shows DSP_3.3V_SW output and DSP_1.8V output, DSP_1.8V rises up first (internal refernce ?) and down to external reference.

Why does this happen? How can I achieve two power IC rise in same slope?

over 1 year ago

0 Febin over 1 year ago

TI__Mastermind 27270 points

Hi,

I will provide an update tomorrow.

Thanks,

Febin

0 Febin over 1 year ago in reply to Febin

TI__Mastermind 27270 points

Hi,

Please have a look at the below App note.

https://www.ti.com/lit/an/slva470a/slva470a.pdf

Thanks,

Febin

0 nia sun over 1 year ago in reply to Febin

Prodigy 20 points

Hello,Febin~

Thanks for sharing! It does help a lot.

Some details want to confirm.

as below picture, does 0.64 in this note apply to TPS628112? and why is it 0.64 ?

0 Febin over 1 year ago in reply to nia sun

TI__Mastermind 27270 points

Hello,

I am on Sick Leave today. Will get back to you tomorrow.

Thanks for your understanding,

Febin

+1 Febin over 1 year ago in reply to Febin

TI__Mastermind 27270 points

Hello,

nia sun said:
as below picture, does 0.64 in this note apply to TPS628112? and why is it 0.64 ?

It's the ratio between the FB voltage and SS/TR voltage. For TPS6281x it will be 1.

Thanks,

Febin

0 nia sun over 1 year ago in reply to Febin

Prodigy 20 points

Hi, Febin~

I have achieved tracking, but there is another question:

Slave has abnormal lift when it's EN able and master is 0V. Why would it happen? How can I fix it?

Thank you.

0 Febin over 1 year ago in reply to nia sun

TI__Mastermind 27270 points

Hi,

Could you please share the latest schematic used for the above measurement?

Thanks,

Febin

0 nia sun over 1 year ago in reply to Febin

Prodigy 20 points

Hi, picture is as blow, I'm checking to see if this abnormal lift is coming from another power supply of the load.

0 Febin over 1 year ago in reply to nia sun

TI__Mastermind 27270 points

Hi,

Let me check the schematic and update you early next week.

Thanks,

Febin

0 Febin over 1 year ago in reply to Febin

TI__Mastermind 27270 points

Hi,

Would it be possible to describe the problem again? I did not understand the term 'abnormal lift'. I could not find anything suspicious from the schematic.

Thanks,

Febin

0 nia sun over 1 year ago in reply to Febin

Prodigy 20 points

Hello, Febin~.
I've circled the anomalous raises in the graph below (rise and fall timings) with red circles.
They both occur when VIN/EN of DSPD1.8V is on and but V TR=0V.

Is it caused by leakage current?

rise

fall

0 Febin over 1 year ago in reply to nia sun

TI__Mastermind 27270 points

Hi,

Thanks for sharing additional details.

Kindly allow me one or two days to review and provide a feedback.

Thanks,

Febin

0 Febin over 1 year ago in reply to Febin

TI__Mastermind 27270 points

Hi,

I am a little confused here.

Earlier you said the lift is when the Master Vin/EN =0V.

nia sun said:
Slave has abnormal lift when it's EN able and master is 0V

But now you said they are ON.

nia sun said:
They both occur when VIN/EN of DSPD1.8V is on and but V TR=0V.

What is V TR?

Could you clarify the Master and Slave in the above schematic? Can you also name all the curves in the graphs above based on the devices?

Thanks,

Febin

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TPS62811-Q1: Track function