TPS25740: TPS25740 Adapter can not chanrge NOTEBOOK when the NOTEBOOK is power off

Supplement：The PDF is sch of the adapter.

TPS25740 sch.pdf

Hi,

Could you get scope captures of Vbus and CC lines for when the laptop is on and off please?

Regards,

Donovan

Hi,

The first sequence diagram is collected when NOTEBOOK is power on,and the second sequence diagram is collected when NOTEBOOK is power off.

I have find a strange phenomenon yesterday : Give a short time 5V power to VBUS line,the adapter can also charge NOTEBOOK when it is power off.

Yellow - CC        Green - VBUS.

When the notebook is turned off, and you try to charge with the TPS25740 there's never a hard reset is there?

Is it possible to get screen shots with the current as well in the same situations? There may be more inrush current when the notebook is off.

Regards,
Donovan

Dear,

When the notebook is turned off, and you try to charge with the TPS25740 there's never a hard reset is there?

Yes,there is not a hard reset in this case. Over-current protection has been closed ,get through replace the 5mΩ with 0Ω.

I have done two experiments to help us to solve the problem.

FIRST:I have try add a Rd (resistance with 5.1K) to TPS25740's CC1,and VBUS is up to 5V certainly when the plug is free;And then I take the adapter's plug into NOTEBOOK' receptacle,the adapter can charge the NOTEBOOK with 20V normally.

SECOND:When the adapter's plug into NOTEBOOK's receptacle when NOTEBOOK is power off,give a short time(about 100+ ms) 5V to VBUS line,the adapter can charge the NOTEBOOK with 20V normally also.

The probable cause i speculate is this:When NOTEBOOK is power off,the NOTEBOOK need a short time(100+ ms) 5V on VBUS to wake up it's PD MODULE;when NOTEBOOK's PD MODULE operate , NOTEBOOK can communicate with PD source normally.Due to TPS25740 supply VBUS 5V time is less than 100 ms,NOTEBOOK's PD MODULE can not operate normally.

But ,I don't now how to modify TPS25740's design to solve problem yet,wating for your help .

Regards,

Huazi

Hi Huazi,

In the notebook off scope capture, can you zoom in on the CC line?

 

It is possible that the notebook does not have Rp when first plugged in and the TPS25740 deglitch time on the CC is too fast and thus never sees an attachment.  

Regards,

Donovan

Hi Donovan,

How can i verify this?

If the CC deglitch is the answer to the question,what should i do to solve it?

The CC line status shows in the following pictures.

 

Regards,

Huazi

Hi Huazi,

It does look like the debounce time of the TPS25740 is too short and is causing the issue. We have seen similar issues with the TPS25740 when used with a TPD8S300. The TPD8S300 will remove the dead battery resistors for a short time (about 400 us) and the TPS25740 sees this as a disconnect due it's short debounce time. Unfortunately there is no fix for the TPS25740 but you could try the TPS25740B which has a longer debounce time. I can ship you and EVM so you can try and see if it charges please email me if you want to try this (d-porter1@ti.com). The TPS25740B will advertise 5, 9, 15, and 20 V though which I know you only need 5 and 20 V.

Could you also post shots of the original adapter working and/or the adapter with the TPS65982 please?

Thanks,
Donovan

Hi Huazi,

One more question. What notebook are you testing with?

Regards,
Donovan

Hi Donovan,

Common test platform is LENOVO X1 Carbon,and other types of LENOVO.

Regards,

Huazi

Hi Donovan,

Thanks for your help, we will try to use TPS25740B to solve the problem .

We are going to have a holiday for the Spring Festival, so the result of TPS25740B I will tell your two weeks later.

Best Regards,

Huazi

Hi Donovan,

We are applying for sample of TPS25740B.

I have a question about TPS25740B : There is the same deglitch time of 120us described in the datasheet of TPS25740 and TPS25740B,is the datasheet of TPS25740B not updated ?

How long is the deglitch time of TPS25740B ?

   

Best Regards,

Huazi

Hi Donovan,

TPS25740B has resolved my issues,Thanks for your help.

Best Regards,

Huazi