BQ40Z50-R2: Power management forum

Chris Chu

Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQ40Z50

Dear TI

Good day!

Our customer have a issue.They test IEC61000 4-3 with Medical Panel PC, the battery pack is lock of PF status(CFETF PF) in fully charge.

We Reproduce test by EMC laboratory, in IEC61000 4-3 test(Radiated RF Immunity), When the frequency is higher than 1G Hz,Gauge IC detects ghost current about 107mA,and into the PF status.

Gauge IC conditions :
1. CHGFET is on.
2. CFETF conditions is 100mA/5S.

Our customer need to know how it happened (Gauge IC detects 107mA in high frequency test)or is there a similar situation.

Regards,

Chris

over 5 years ago

0 Steven Yao over 5 years ago

TI__Genius 12215 points

Chris

Such issue could be typically caused by layout, Please check the layout against the guideline the section 11 in bq40z50 datasheet on the website, for RF immunity, one more thing to be noted is that the trace at anode of any diode or Zener should be as shorter as possible

The thing confuses is that is this issue occurred when CHGFET or on? Detect a current when CHGFET is on should not incur a CFETF fault, is that a typo?

If not, when you leave CHGFET on and apply a 107mA charge current, do you still perceive this issue?

0 Chris Chu over 5 years ago in reply to Steven Yao

Prodigy 50 points

Hi Steven

Thank you for your reply. I will check our layout.

This issue is in fully charge and FC flag to 1, (FC condition : 300mV/250mA),the CHGFET is set 1,so when FC flog is to 1 and turn off the CHG FET.

Read Device current data ,The PF current is 107mA .but it’s a problem , The FC flag is to 1 when charge current =237mA.because Charge MOS FET is fault, The fuse is blows in 3~7 seconds,but current drop in 5~7 seconds, should not be drop of 107mA.

So i suppose the 107mA not should be a real current,it is probably the Gauge ic detect voltage difference on current shunt by RF radio frequency interference.

Regards,

Chris

0 Steven Yao over 5 years ago in reply to Chris Chu

TI__Genius 12215 points

Chris

This makes sense, then the 107mA current could be ghost current incurred by injured interference energy somehow, it could be coupled into the circuit via some trace functions like antenna, some long traces at anode side of diode or Zener can make this function.

0 Chris Chu over 5 years ago in reply to Steven Yao

Prodigy 50 points

Hi Steven

Thanks, that really help, I will try to solve the problem of Anti-RF radio frequency interference.

Regards,

Chris