Design for 50VDC to 3.3VDC converter

[vish2207]

I have an input voltage around 50VDC and I want to derive power for MCU from the same source. The output voltage is +3.3VDC 2A.

Please suggest the most cost effective devices for the circuit.

I have seen the TI Webench Designer for power and they have excellent designs and every possible solution. But when I buy a perticular TI or any other part in retail the same 3$ part will become 10$. Which is not desirable.

So, I want some suggestions of parts which are readily available in the local market so they will be cheaper.

Thanks,
Vishal

 

[ajapyy]

use 2 resistor and bring source voltage level to low level such 5VDC. and then use regulator like LM317, lf33, lm1117-3.3 or any regulator that do same work.

 

[alexan_e]

I have an input voltage around 50VDC and I want to derive power for MCU from the same source. The output voltage is +3.3VDC 2A.

Please suggest the most cost effective devices for the circuit.

use 2 resistor and bring source voltage level to low level such 5VDC. and then use regulator like LM317, lf33, lm1117-3.3 or any regulator that do same work.

If the task in to get an output of 3v3 2A to feed the mcu board and the source is 50v then a resistive divider would have to dissipate 46.7v * 2A which is about 90W...
Apart from that using a resistive divider is probably the most inefficient way to lower a voltage.

 

[vish2207]

Thanks for the options given by you.

Can anyone suggest the most common Switching regulator ICs?

 

[mtwieg]

You have a couple options:
1. Use a transformer-based topology (flyback or forward) to achieve the high step-down ratio with a simple controller.
2. Use a specialzed controller which is capable of operating with very low duty cycles. For best efficiency you should use a synchronous converter with external FETs.

 

[ArticCynda]

It depends what your ripple requirements are, but for standard MCU applications I would recommend a monolithic buck converter IC with external inductor, flyback diode and capacitors to lower the BOM cost. Take a look at the LT1074 from Linear Technology for example, it can handle inputs up to 60V and easily supply 2A of output current at 3.3V.

 

[--BawA--]

If efficiency is an issue , just go for SMPS . use flyback or forward converter .
otherwise design a linear regulator using zener and bjt.

 

[vish2207]

[Solved] Re: Design for 50VDC to 3.3VDC converter

Hi All,

Thanks for your suggestions. I appreciate that.

I have finalized the Switching Regulator LM2576HV from Simple Switcher family of TI. It have maximum input voltage of 57V and 3A max output current. It needs just 4 external components. So, it is super easy to use and costs about $5.

I hope this thread will be treated as Solved now.

Thanks everyone.