TPS40041: Buck converter for 120V input

user6167404

Part Number: TPS40041
Other Parts Discussed in Thread: TPS64203, LM5169, LM5164

Hi,

I'm in need of a synchronous (for high efficiency) DC-DC buck converter with a 120V (max) input and 3V output. Is it possible to use TPS40041 where VDD is initially generated from 120V through a resistor? The VDD is also connected from o/p via a diode, so it can draw current from o/p after start-up.

I cannot find any part for buck converter/regulator that can handle 120V input and 3V/800mA output current.

Also like to consider TPS64203, but this one is not a synchronous.

over 1 year ago

0 Timothy Hegarty over 1 year ago

TI__Mastermind 49037 points

Take a look at this 120V, 300mA converter: https://www.ti.com/product/LM5168

0 user6167404 over 1 year ago in reply to Timothy Hegarty

Prodigy 40 points

I have seen this, but my requirement needs more current, probably LM5169 is an option, unfortunately not available now.

0 Timothy Hegarty over 1 year ago in reply to user6167404

TI__Mastermind 49037 points

The LM5169 is rated at 650mA. If you can accept 100V max Vin by clamping or limiting the input transient, then the LM5164 100V, 1A converter is an option.

0 user6167404 over 1 year ago in reply to Timothy Hegarty

Prodigy 40 points

Unfortunately not. Can you see any possible problems with my idea of using TPS40041?

0 Timothy Hegarty over 1 year ago in reply to user6167404

TI__Mastermind 49037 points

Abs max on SW is 10.5V, so that wouldn't work. The high-side FET's gate must go above VIN during its on time.

I think your best option is to limit the max Vin, especially if it's a transient.

0 user6167404 over 1 year ago in reply to Timothy Hegarty

Prodigy 40 points

My bad, I didn't think about the voltage at the high side driver's source when the MOSFET is turned ON.

Alternatively, I think the TPS64203 may work with a floating ground, if I only need current regulation without voltage feedback.

0 Timothy Hegarty over 1 year ago in reply to user6167404

TI__Mastermind 49037 points

Not sure what you mean by floating GND. I doubt you can use a 6.5V converter for a 120V application. In any event, 800kHz switching frequency is too high at such high input voltage.

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TPS40041: Buck converter for 120V input