TPS2546: TPS2546 USB certification issue

AJ Cheng

Part Number: TPS2546
Other Parts Discussed in Thread: TPS2547, , TPS2549

My customer used TPS2546 can not pass the USB certification. We got fail about A4.9: Host Test J/K, SE0_NAK (EL_9) in SDP / CDP mode.

SDP mode Test K in D+ is over 20mV and D- is pass. CDP mode Test J in D- is over 20mV and D+ is pass. Do you have any suggestions? Thanks for help~

over 7 years ago

0 Atiq Rahman over 7 years ago

TI__Expert 5110 points

AJ,

Could you share the schematic for the design so that our team can review and provide you input on this certification failure?

Regards,
Atiq

0 AJ Cheng over 7 years ago in reply to Atiq Rahman

Genius 3615 points

Dear Atiq.

Please reference on below and thanks for kindly help~

0 AJ Cheng over 7 years ago in reply to Atiq Rahman

Genius 3615 points

Dear Atiq.

Update more. Thanks~

0 Yu-Ning Lee over 7 years ago in reply to AJ Cheng

TI__Intellectual 1990 points

has the voltage been measured on DM_OUT and DP_OUT pins when the test fails? Please also confim the mode the device is in when the test fails(CTL* mode level)

0 AJ Cheng over 7 years ago in reply to Yu-Ning Lee

Genius 3615 points

Dear Yoon.

When test fail the DM_OUT is 24~27mV and DP_OUT about 400mV. Test is in CDP mode.

We change TPS2546 to TPS2547 also got fail. Please kindly help it.~

0 Yu-Ning Lee over 7 years ago in reply to AJ Cheng

TI__Intellectual 1990 points

Hi AJ, I think it may be the USB host/hub controller contributing to the offset. Could you check the DM_OUT and DP_OUT voltage, DM_IN and DP_IN while EN = low. This should disable the signal switch. If offset voltage measured on DM_OUT and DP_OUT while EN = low, the offset may be driven by the USB host/hub controller.

0 Jerry Chang over 7 years ago in reply to Yu-Ning Lee

Prodigy 20 points

Dear Yoon,

We test as below, if need any more information, please let me know, thanks!

While EN = low.

DM_OUT=5.177V

DP_OUT=4.084V

DM_IN=27mV

DP_IN=21mV

While EN = low, under Test J condition.

DM_OUT=5.177V

DP_OUT=3.089V

DM_IN=31mV

DP_IN=24mV

0 Yu-Ning Lee over 7 years ago in reply to Jerry Chang

TI__Intellectual 1990 points

Just to confirm, non driven signal lines(D+ or D-) need to be below +/-10mV to pass when measured at the connector, correct?

What is the measurement condition? WIth the sQuidd board attached? Are DM_IN and DP_INs connected to the connector? What is the connection between DP1L/DM1L and DP1L_C/DM1L_C?

DM_OUT/DP_OUT connected to the host controller?

0 Yongqiang Sun over 7 years ago in reply to Jerry Chang

TI__Intellectual 2685 points

Hi,

‘The issue is due to a conflict between the Test_J and the BC1.2 Spec.

Test_J places a 400mV DC signal on the D+ line. This happens to be within the window where the BC1.2 spec defines primary detection.

Thus, the TPS2546 sees a primary detection voltage on D+ and since the TPS2546 is in CDP mode, it responds by putting VDM_SRC on D-.

In a normal CDP situation the D- voltage would be around 0.6V. But this is not a normal situation since the D- line is loaded with two 45 ohm resistors in parallel for a total D- resistance to ground of 22.5 ohms.

The maximum D- load in primary detection is 250uA. Meanwhile, 0.6V into 22.5 ohms is over 25mA.

So the Test_J is both triggering primary detection and placing a short circuit on D-. Now the TPS2546 is designed to protect against a primary detection short and has a 1mA (typ) current limit on the D- output.

So now we can see that a 1mA current limit into a 22.5 ohm load will obtain the 22mV voltage on D-.

This issue only occurs when a Test J packet is sent on a CDP with a standalone battery charging device(TPS2546 in this case), not a real world condition hence does not have impact on real application.

0 Jerry Chang over 7 years ago in reply to Yongqiang Sun

Prodigy 20 points

Hi Yongqiang Sun,
Thanks for your reply.
Cause our product need to pass USB certification, please let me know how to explain Allion Lab cause they follow USB-IF's requirement, any method to pass/waive the Test_J?

0 AJ Cheng over 7 years ago in reply to Jerry Chang

Genius 3615 points

Dear Yongqiang .
Do you have any suggestion? We need your help. Thanks~

0 Yongqiang Sun over 7 years ago in reply to Jerry Chang

TI__Intellectual 2685 points

Hi,

if passing the Test-J is mandatory, I think customer will have to change to TPS2549, TPS2549 can pass the test-J. we have a detailed report, please send me an email and I will share the report with you. yongqiang-sun@ti.com

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TPS2546: TPS2546 USB certification issue