BQ25792: REGN pin fails whenever battery is connected to the charging board

Hi Pulipati,

Can you provide your schematic?  Even if not used, SYS pin must have the minimum capacitance after derating per the datasheet.  

Regards,

Jeff

Charging chematic bws.pdf

This is my schematic 

Hi Pulipati,

On the schematic, are ILIM_HIZ and current sensing 1kohm resistors only placeholders?  If not, they charging will not work correctly with them.  Also, after the 100 ohm resistor, BATP must connect to the battery PACK+ terminal but the net label says "source"? 

Regarding "REGN being shorted", REGN turns off (goes HiZ not shorts) in battery only or forced HiZ mode using the EN_HIZ bit.  The charger auto sets EN_HIZ bit = 1 in the event of high current or SYS short faults.  What is the ISAT rating of your inductor?

Regards,

Jeff

But sir when i check using multimeter the resistance between Regn and Gnd is below 60ohms  and for ilim hiz pin i placed resistors  per the datasheet i used 127k and 100k  and i used current sensing resistor R21- 0.01ohms ,R15-0.01ohms and even BatP is connected to the positive terminal of the battery pack , i connected source label for BAT pin 

ISAT rating of my inductor is 14.1A

There is no short in solder but my ic is damaged i could not find the reason even i replaced another ic but still i am facing this issue pls help me out .I just want to know to know the reason for this issue , Is there any way to check this issue by checking any parameters in the ic

But the ic still comunicates via i2c 

Hi Pulipati,

REGN has protection for overcurrent.  The only time I have seen REGN is damaged is from overvoltage at VBUS.

Regards

Jeff

But my vbus voltage is 5v and current is 1A  it worked well when i didnot connect my battery but when i connect my battery immediately regn pin doesnot show any voltage and after disconnecting the power i checked the  resistance between regn and gnd which is short is less than 60 ohms now tell me what can be the reason

Hi Pulipati,

I do not understand why adding the battery causes an issue. Does the same thing occur with no battery but adding a resistive load on ISYS that requires the same current? The REGN resistance to ground of 60 ohm is a problem that needs to be addressed.  But that only loads 5V/60ohm = 8.3mA on REGN with max output of 30mA.  When switching, the current from REGN is used to power the gate drive of switching FETS.  So, more ISYS and/or IBAT current requires more current from REGN.  With a high enough rated capacitor (at least 10V preferable 16V to account for deration), REGN should not collapse.  

Regards,

Jeff