TPS92410: Can TPS92410 drive 20~25pcs of white LED from AC100V without TPS92411?

Hello Kazuya,

Yes, it can. It will only conduct current when the AC voltage is above the LED stack. Are they concerned about efficiency? The TPS92410 is a linear current regulator. The TPS92411 is a bypass switch, they work separate from each other so they aren't needed for each other though it does make for a more efficient better operating system.

Best Regards,

Hello Irwin,

Thank you for your reminding and I'm sorry for my late response.

I understood the efficiency is not good because TPS92410 is linear current regulator and most of power is consumed
at the external NMOSFET.

Could I ask you a few questions?

Q1. Can TPS92140 turns LED on and off without TPS92411 using ADIM terminal?
Q2. Is there document which explains how to choose the external NMOSFET?
Q3. If the input voltage is 100V AC, should the external NMOSFET maximum voltage of Vds be higher than 141V?
I think TI daosen't have such higher Vds MOSFET, so do they need to choose FET from other company?
Q4. If all TPS92411 are removed from TPS92410 EVM001, which peforformance of the EVM get worse?

Thank you again and best regards,
Kazuya Nakai.

Hello Kazuya,

1) Yes
2) It's part of the design process, there is some explanation in the datasheet however it just needs to meet SOA and have a high enough voltage rating.
3) If this is connected to the AC line you have to take into account high line, surge and any other disturbance that can cause the voltage to be high. I would suspect you would be looking at a 400 Vds rated MOSFET or high to have margin and be able to clamp input surges.
4) The power factor would drop significantly. It will still work but it will only light the LEDs when the input voltage is higher than the total LED stack voltage, stack 1 + stack 2 + stack 3. At 100 VAC it will be close to not working because the EVM was designed for 120 VAC. You could run it at 120 VAC to see how it will behave, or short some of the LEDS out, probably just the lower stack so it's only lighting the top and middle stack.

Best Regards,

Hello Irwin,

Thank you very much for your reply.
I knew that the customer was considering using ON semi, NUD4011 too.

NUD4011:
www.onsemi.jp/.../NUD4011-D.PDF

Their application would be like Figure 10 on page 7 of NUD4011 datasheet.
I think TPS92140 can be used instead of NUD4011.
Is my understanding correct?
If there is any concern for it, could you please let me know?

Thank you and best regards,
Kazuya Nakai.