Part Number: BQ24618
I'm still investigating, but it seems as though anytime I plug the battery in first I need to replace the Low-side NMOS. Is this something you have seen in the past?
Can you please show scope capture on the issue when damage occurs?
Application Engineer, Battery Charging Products
Please click "This resolved my issue" button if this post answers your question.
We are glad that we were able to resolve this issue, and will now proceed to close this thread.
If you have further questions related to this thread, you may click "Ask a related question" below. The newly created question will be automatically linked to this question.
In reply to Jing Zou:
In reply to JPAlleyne:
Cell count= 6
FET Voltage Rating = 40V
Here is the Schematic (we added the missing cap on SRP):
Well I haven't fully tested it but initial findings showed that there is the potential that the IC got damaged as well. You said that a large current would flow through the body diode of Q3 and then go to ground.
1) What path would it take to go to ground through Q3's body diode?
2) Is the voltage spike caused by the large current flowing through the inductor?
3) Is it the voltage spike that causes damage to components on the PH node?
4) What can I do to protect the circuitry right now, without major redesign?
Regarding 1, please see the path marked below.
Regarding 2, yes.
Regarding 3, I cannot conclude without look at scope captures.
Regarding 4, when battery is plugged in, the drain of the lowside mosfet rises fast which might bring up the gate voltage and cause damage. One solution is to add more capacitance at Cgs to hold gate voltage down. Or try to find a replacement of the low side FET which Cgd is less than Cgs.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.