BQ24251 USB eye pattern verify

Eric Chen4

Expert 2370 points

Other Parts Discussed in Thread: BQ24251

Hi,

As I know, TI BQ24251 is fully BC1.2 compatible parts.

But when verify USB eye pattern then got fail report at Battery full.

Please kindly provide the verify method or relate verify report for our reference.

Thanks.

0 Wenjia Liu over 9 years ago

Can you specify the details of the failure? Can you also share the application schematic for further review?

Thanks,
Wenjia

0 Eric Chen4 over 9 years ago in reply to Wenjia Liu

Expert 2370 points

Hi WenJia,

Provide USB connect method & schematic for your reference.

Then remove the BQ24251 IC and USB eye pattern testing pass.

Please kindly provide your comment for our reference.

Thanks.

0 Wenjia Liu over 9 years ago in reply to Eric Chen4

For the eye pattern test, can you suggest the customer add isolation resistors between the USB lines and our D+/D- pins? A few ohms will do.

BTW, the ILIM and ISET calculation doesn't seem correct to me. The KISET is 250 and KILIM is 270, so based on the resistor value in the schematic:

IFC = 250/120 = 2.08A

ILIM = 270/174 = 1.55A.

Thanks,

Wenjia

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