On page 3 of the EVM user guide, Table 3 states that the max charge current recommended is 8A. I was wondering if this is due to the copper thickness and trace width of the PCB or if it is due to other components besides R6 and L1. According to the BOM on page 10 of the same document, the FET's are rated at 20A, so I'm not sure why the recommended max is 8A.
Thanks in advance for any assistance you can provide!
FETs are never used at full rating in a good design. All components should be derated for a reliable design. Most designs have to work over a large range of temperatures and layout conditions.
FETs are typically rated at their maximum current when it is perfectly cooled (large heat sink), at 25C ambient and fully on at their lowest RDSon rating.
The EVM can probably be pushed higher in current if temperatures are kept in check.
I figured that's what was going on. I'm only planning to use 10A which is still well below the FET's rated current. Hopefully I don't have heat issues, but if I do, at least I'll know why.
Out of curiosity, do you know what the copper thickness/trace width is on the EVM board? I didn't see this listed anywhere...
We use 2 oz copper which should be ~0.0028 inches thick.
I have designed the 10A Mppt controller unit with BQ24650. The unit's efficiency is over 91%. and all charging functions are great. But I found some questions.For example, The BQ24650 operation circuit is 2mA with the 2A charging current, but the BQ24650 operation circuit is 60mA with the 10A charging current. On account of the larger operation circuit, the IC is very hot when the unit is charging the battery.
I think the mosfets are the voltage control components, the mosfets aren't effected by the loading current. So I have a question, why is the BQ24650 operation circuit larger with the 10A charging current?
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.