CSD19536KCS: CSD19536KCS

Hello Daniel,

Thanks for the inquiry. I am the applications engineer for TI's power MOSFET product line. I'd recommend at least a 80V FET for your application. The CSD19536KCS is TI's lowest on resistance 100V device in TO220. Max Rds(on) = 2.7mΩ at VGS = 10V & T = 25°C. It's also the highest cost FET in this package. We have lower cost/higher resistance FETs in the same package depending on the current requirements. I see a max input current of 12ADC to the inverter. Is this the max current that the FET needs to conduct? Please share the max current requirements for the FET and I can make a better recommendation. After selecting the FET, I can reassign this thread to TI's BMS applications team.

Best Regards,

John Wallace

TI FET Applications

Yes, we are limited to the microinverter which can continuously discharge 380-384 watts

Hi Daniel,

Using 12ADC max, VGS = 10V and T = 65°C, the calculated conduction loss for the CSD19536KCS is about 0.5W. Two lower cost/higher Rds(on) alternatives include the CSD19534KCS (3.1W) and the CSD19533KCS (1.9W). A thru-hole TO220 package capable of dissipate 5W or more with a heat sink and airflow. We also have SMT versions (KTT suffix) of these devices as well as 5x6mm SON packaged FET such has CSD19531Q5A (1.2W) if you want to use surface mount package. Please let me know if you have any questions. If not, I will reassign this thread to the BMS applications team.

Thanks,

John

This is perfect, thank you. That is the main problem as a normal BMS only lasts 4-5 years unless its from Delta Electronics. Oak Ridge National Lab has a potential 25 year BMS they use for Nuclear but they are unsure of themselves!

I actually have these questions                                                                                                                                                                                                                              "

• Thermal Dissipation: Given that the micro inverter will handle up to 380 watts of continuous power, will the suggested MOSFETs (like the CSD19536KCS with a conduction loss of 0.5W) still maintain stable operation within the expected thermal conditions of your setup? Is there a recommendation for specific heat sink sizes to manage these thermal loads?

• Compatibility with LTO Cells: LTO cells typically have high charge/discharge rates and different characteristics compared to other lithium-based batteries. Are there any considerations with these MOSFETs when handling the high current spikes often seen with LTO cells?

• Micro Inverter Integration: Will the 12V gate-source voltage (VGS) and the specific MOSFET alternatives provided be optimal for interfacing with the micro inverter and handling the continuous load of 380 watts efficiently?

• Surface Mount Options: Would the SMT versions, particularly the 5x6mm SON packaged FET (CSD19531Q5A), be better for compact designs in this module? Can they reliably handle thermal dissipation without a heat sink?"

Hi Daniel,

Please see technical article at the link below. This provides "rule-of-thumb" maximum power dissipation for the various TI FET packages.

• I used 12ADC current to calculate the conduction loss in the FET. Yes, a TO220 will maintain stable operation with 0.5W of dissipation. It can actually dissipate much more power depending on ambient conditions. use of a heat sink and airflow. There are many heat sink manufacturers that make TO220 heat sinks.
• FETs are very good at handling high currents including spikes. You can use the transient thermal impedance graph from Figure 4-1 in the datasheet to estimate the junction temperature rise due to single pulse and repetitive pulses of current. The second link below is to a technical article on using the transient thermal impedance graph.
• AS long as the gate is driven to VGS ≥ 6V, the FET should work for this application. Using a higher gate drive voltage, VGS = 10V -12V will reduce the conduction loss since Rds(on) is lower at VGS = 10V than at VGS = 6V.
• The maximum dissipation of the 5x6mm SON package is about 3W on a well-designed multilayer PCB with thermal vias and maximum copper area. Most customers like to limit the dissipation to a lower value to maintain good thermal margins.

https://www.ti.com/lit/pdf/sszt389

https://www.ti.com/lit/an/sluaat8/sluaat8.pdf

Thanks,

John

How does this workplan look for my battery MOSFET guy?                                                                                                                                                                           "

Work Plan for Jessie: Integrating and Testing the MOSFET for Microinverter Discharge

1. Install the MOSFET (CSD19536KCS):

   • Wire the MOSFET between the battery module and the microinverter to control discharge.
   • Ensure a VGS of 10-12V for optimal performance, minimizing conduction losses.

2. Thermal Management:

   • Install an appropriate TO220 heatsink to dissipate the 0.5W conduction loss from the MOSFET.
   • Ensure proper airflow around the MOSFET for continuous operation.

3. Test Setup:

   • Run tests to ensure the MOSFET manages the 380-384W discharge limit of the microinverter efficiently.
   • Monitor thermal performance and voltage levels to ensure stable operation.

4. Documentation:

   • Yes, send both TI PDFs to Jessie.
   • Key sections:
     • TI1 PDF: Focus on thermal dissipation and use of a heatsink for the TO220 package (important for long-term operation).
     • TI2 PDF: Review transient thermal impedance (for spikes), specifically Figure 4-1 for understanding junction temperature behavior."

Hi Daniel,

Yes, this sounds good. I don't think you will need a heat sink but you can research this on your own. I have reassigned this to our BMS apps team to help you with your BMS design.

Thanks,

John

Nice :). Thank you John 

Do you have a BMS that can support 24 cells instead of 16? Is there a BMS that could last 15-20 years with high quality components? Each 1 kWh Battery Module will only discharge at .2 C roughly 380 watts as we are limited to the Enphase Microinverter so no crazy high power. Even though the battery module can peak at 19000+ Watts for 10 seconds lol.

Nice. It would discharge 380 watts about .2 C. Could the board last 15-20 years? I see only a 1 year warranty. If not is it possible to add better components?

So if we add mosfets and good board components this could last 10-20 years? Sorry if Im asking the same question kind of.

Yes, if the components are well quality then they will last a long time.

Regards,

Adrian