BQ25792: REGN pin shorts

Pulipati Lakshmi Viswanadh

Part Number: BQ25792

Tool/software:

Hi sir whenever i connect c type usb of voltage 5v to Vbus i am facing issue in Regn pin ,Regn voltage is present for few seconds then it is not present so i replaced the capacitor of 4.7uf with 50 v rating immediately regn voltage is dropped from 0.5v to 0v followed by i checked the continuity resistance it is short with Gnd .Can u mention what are the possible reasons for this REGN pin failure ? Because initially after soldering the ic I checked the resistance between Regn pin and Gnd it is 493ohms only after giving supply to the ic iam facing this issue.

kindly give me possible reasons for this failure of regn pin

3 months ago

0 Jeff F 3 months ago

TI__Guru**** 166626 points

Hi Pulipait,

493ohms is a bit low for REGN to ground. On the EVM, I measure 10kohm to GND. I think your board has a soft short to GND on REGN that is tripping its sort circuit protection.

Regards,

Jeff

0 Pulipati Lakshmi Viswanadh 3 months ago in reply to Jeff F

Prodigy 30 points

what are the possible reasons for the REGN pin to fail

0 Jeff F 3 months ago in reply to Pulipati Lakshmi Viswanadh

TI__Guru**** 166626 points

Hi Pulipati,

Since it has integrated over current protection, the most likely fault is overvoltage. But, overvoltage at VBUS would likely damage other internal circuits. It is unlikely that a usb-C port would overvoltage the IC. I recommend you measure the resistance to ground on a PCB without the charge IC installed to confirm it is not a PCB fab issue.

Regards,

Jeff

0 Pulipati Lakshmi Viswanadh 3 months ago in reply to Jeff F

Prodigy 30 points

But my Vbus voltage is 5V with current rating 2.5A then how come over voltage issue come? which resistance you are saying to measure with respect to Gnd are u refering to Regn pin

0 Jeff F 3 months ago in reply to Pulipati Lakshmi Viswanadh

TI__Guru**** 166626 points

Hi Pulipati,

Yes, please measure the resistance across the REGN capacitor pads with no IC installed.

Regards,

Jeff

0 Pulipati Lakshmi Viswanadh 3 months ago in reply to Jeff F

Prodigy 30 points

it shows open resistance in multimeter

0 Pulipati Lakshmi Viswanadh 3 months ago in reply to Pulipati Lakshmi Viswanadh

Prodigy 30 points

Yesterday i checked the damaged board using evm board and i attach the observed parmaters

Only WD_Flag_INT flag is highlighted

EN Hiz is enabled and EN charge is enabled

0 Pulipati Lakshmi Viswanadh 3 months ago in reply to Pulipati Lakshmi Viswanadh

Prodigy 30 points

sir there is no any pcb fab issue ,is there any other reason other than overvoltage scenerio for this issue because my vbus voltage is 5v it is within the range any other reason for this overvoltage simulation

0 Jeff F 3 months ago in reply to Pulipati Lakshmi Viswanadh

TI__Guru**** 166626 points

Hi Pulipati,

If EN_HIZ is being autoset, the there is likely an overcurrent fault. Can you measure the resistance of the other converter pins (SW1,SW2, BTST1, BTST2, VBUS, SYS, PMID and BAT to GND?

Regards,
Jeff

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BQ25792: REGN pin shorts