TPS2549-Q1: iPhone restarted automatically

Kuramochi Tadahiko

Guru 28715 points

Part Number: TPS2549-Q1
Other Parts Discussed in Thread: TPS2549, TPS2546

Hi,

My customer is evaluation the TPS2549-Q1 with the EVM.

They tried to connect iPhone6S with the TPS2549EVM and switched off the iPhone6S.

After switching off, the iPhone6S restarted automatically.

What is this cause?

They also confirmed followings;

・The iPhone does restart when the TPS2549 is CDP AUTO SWITCH mode(CTL1,2,3,=HIGH), then VBUS drops and rises up.

・The iPhone does not restart when not connected with the EVM.

・The iPhone does not restart when the TPS2549 is SDP mode(CTL1,2=HIGH CTL3=LOW).

・The iPhone does not restart when the TPS254"6" is CDP AUTO SWITCH mode(CTL1,2,3,=HIGH).

Best Regards,

Kuramochi

over 8 years ago

0 Eric Wright over 8 years ago

TI__Mastermind 42795 points

Hello,
If possible, can you provide waveforms for each case clearly showing VBUS, D+, D- and load current?

0 Kuramochi Tadahiko over 8 years ago in reply to Eric Wright

Guru 28715 points

Hi Eric-san,

Please find attached.

TPS2549-Q1 Waveform.xlsx

The iPhone6s seems to restart automatically during power off when it detect VBUS.

My customer is thinking that what the TPS2549 cuts the VBUS when the iPhone6s is switched off is the cause.

Is it correct ?

Best Regards,

Kuramochi

0 Yongqiang Sun over 8 years ago in reply to Kuramochi Tadahiko

TI__Intellectual 2685 points

Hi Kuramochi-san,

when iPhone6S powered off, iPhone6s will not implement secondary detection and enumeration signal. it will trigger TPS2549 CDP-SDP auto switch. Please see section 8.3.6 in TPS2549 datasheet.

0 Kuramochi Tadahiko over 8 years ago in reply to Yongqiang Sun

Guru 28715 points

Sun-san,

Thank you for your help.

I understood the cause dropping VBUS.

>・The iPhone does not restart when the TPS254"6" is CDP AUTO SWITCH mode(CTL1,2,3,=HIGH).

Why do the operation of the TPS2549 and TPS2546 different?
I can see what is written to the data sheet in the same way.

Best Regards,
Kuramochi

0 Yongqiang Sun over 8 years ago in reply to Kuramochi Tadahiko

TI__Intellectual 2685 points

Hi Kuramochi-san,

TPS2546 and TPS2549 have same behaviors in CDP mode when iPhone6S powered off. customer found they have different behaviors, so I guess they tested TPS2546 CDP mode when iPhone6S is powered on not powered off.

By the way, could you please share some waveforms to us (both TPS2546 and TPS2549) ? we can help to analyze the reasons.

you can directly send emails to me : yongqiang-sun@ti.com

Kuramochi

0 Kuramochi Tadahiko over 8 years ago in reply to Yongqiang Sun

Guru 28715 points

Hi Sun-san,

What behaviors of the TPS2546 and the TPS2549 are different was my customer’s misunderstanding.

So please forget this topic.

And I have additional questions.

I would like to understand the principle of the following waveform.

4478.TPS2549 waveform detail.xlsx

I think that this behavior is different from the "8.3.6 CDP and SDP Auto Switch" on the datasheet.

For example;

・There are three D+/- pulses on the ①(I think these pulses should be one).

・VBUS reset is executed two times.

Could you explain the principle of behaviors from ① to ⑤?

Best Regards,

Kuramochi

0 Yongqiang Sun over 8 years ago in reply to Kuramochi Tadahiko

TI__Intellectual 2685 points

Kuramochi-san,

1. after being attached, iPhone applied three 0.6V voltages on D+ line, because TPS2549 operates in CDP mode, so TPS2549 will also apply three 0.6V voltages on D- line. TPS2549 didn't detect any enumeration signal 2 seconds after the primary detection, so TPS2549 would discharge and switch to SDP mode.

2. after discharging, TPS2549 operated in SDP mode, at this time iPhone applied a 0.6V voltage on D+ line, because TPS2549 operated in SDP mode, so TPS2549 wouldn't apply any voltage on D- line. TPS2549 would only stay 2 seconds in SDP mode, and then it switched back to CDP mode without discharging.

3. iPhone applied a 0.6V voltage on D+ line, because TPS2549 had switched back to CDP mode, so TPS2549 would apply a 0.6V voltage on D- line. TPS2549 didn't detect any enumeration signal 2 seconds after the primary detection, so TPS2549 would discharge and switch to SDP mode.

0 Kuramochi Tadahiko over 8 years ago in reply to Yongqiang Sun

Guru 28715 points

Sun-san,

Thank you for your answer and I have an additional question.
Could you tell me why iPhone applied "three" 0.6V voltages on D+ line on the ① if you know?
Is this iPhone's matter?

Best Regards,
Kuramochi

0 Yongqiang Sun over 8 years ago in reply to Kuramochi Tadahiko

TI__Intellectual 2685 points

Kuramochi-san,

This is iPhone's matter, I also have no idea why iPhone applied three 0.6V voltages on D+ line.

0 Kuramochi Tadahiko over 8 years ago in reply to Yongqiang Sun

Guru 28715 points

Sun-san,

Thank you for your answer.

I have an additional question.

The iPhone started a new detection on ③.
I think that this behavior is not supposed for the TPS2549-Q1.
I s it correct?
And please let me konw me why iPhone started a new detection on ③ if you know?

Best Regards,
Kuramochi

0 Yongqiang Sun over 8 years ago in reply to Kuramochi Tadahiko

TI__Intellectual 2685 points

This is iphone behavior, I also have no idea why iPhone started a new detection, according to my tests, different smartphones have different behaviors when powered off.

0 Kuramochi Tadahiko over 8 years ago in reply to Yongqiang Sun

Guru 28715 points

Hi Sun-san,

I receive an additional question from customer.

Does TI grasp this iPhone restarting phenomenon?

Best Regards,
Kuramochi

0 Kuramochi Tadahiko over 8 years ago in reply to Kuramochi Tadahiko

Guru 28715 points

Hi Sun-san,

I was received additional questions from my customer.

Can the discharge function be invalidate on the CDP mode?
And can wait time(2sec) be extended?
(I recognize that it is impossible...)

My customer hopes to be developed the TPS2549 which is not implemented discharge function on the CDP mode as your reference.

Best Regards,
Kuramochi

0 Kuramochi Tadahiko over 8 years ago in reply to Kuramochi Tadahiko

Guru 28715 points

Hi Sun-san,

How about this situation?

Best Regards,

Kuramochi

0 Eric Wright over 8 years ago in reply to Kuramochi Tadahiko

TI__Mastermind 42795 points

Hi Kuramochi-san,

A design change to TPS2549-Q1 for a new discharge (or no discharge) behavior is a business decision and will require direct (email/phone) contact with the Shenzhen team. If there are more technical questions, please go ahead and refresh them.

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TPS2549-Q1: iPhone restarted automatically