# 48V to 12V GAN HEMT based DC-DC Converter with VOLTAGE REGULATION & NON-ISOLATED for AUTOMOTIVE APPLICATIONS

#### mohtishamali

Joined Jul 9, 2021
19
Greetings of the day to all,

I am working on 48V to 12V GAN based non isolated DC to DC converter with regulated output. I am very confused in selecting topology for my application as I am beginner in this field. Can someone here who has already worked om similar sort of topic suggests me any leads to that, it would be highly appreciated. Any leads to a research work related to that would be great. Its been two months now since i started working on this topic but i still don't have any direction and just feeling very depressed and confused. I am looking forward to have valuable output from all seniors here.
Below are the basic parameters of my GAN based Converter.

Input Voltage: 30V to 65V

Nominal Input Voltage: 48V

Output Voltage: 9V to 17V

Nominal Output Voltage: 12V

Output Power: 1KW

Switching Frequency: 500kHz to 1 MHz

#### Papabravo

Joined Feb 24, 2006
18,457
Since you are a beginner I'm going to suggest the simplest possible solution first. If for some reason you find it unsuitable then we can proceed to more complicated designs. I suggest you get yourself a comprehensive and recent texbook on switch mode power supplies. That way you will have a reference as we go along. My initial suggestion would be to consider a buck regulator with a GAN HMET active switch and a diode for the the recirculation switch.

The proposed output power of 1KW means that you will be drawing 83.3 Amperes. This power level may be too much for ordinary PCB methods. Anyway using an efficiency of 85% for a back of the envelope calculation we see that the required input power will be 1KW/0.85 ≈ 1.177 KW. At 48 Volts input, that power level will require 24.51 Amperes. The inductor for a buck regulator should be able to handle twice that current WITHOUT saturating. That is a TALL order. I don't know where you think you will get your magnetics from, but you need to conduct a careful search.

Let me know how it goes.

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#### mohtishamali

Joined Jul 9, 2021
19
Since you are a beginner I'm going to suggest the simplest possible solution first. If for some reason you find it unsuitable then we can proceed to more complicated designs. I suggest you get yourself a comprehensive and recent texbook on switch mode power supplies. That way you will have a reference as we go along. My initial suggestion would be to consider a buck regulator with a GAN HMET active switch and a diode for the the recirculation switch.

The proposed output power of 1KW means that you will be drawing 83.3 Amperes. this power level may be too much for ordinary PCB methods. Anyway using an efficiency of 85% for a back of the envelope calculation we see that the required input power will be 1KW/0.85 ≈ 1.177 KW. At 48 Volts input, that power level will require 24.51 Amperes. The inductor for a buck regulator should be able to handle twice that current WITHOUT saturating. That is a TALL order. I don't know where you think you will get your magnetics from, but you need to conduct a careful search.

Let me know how it goes.
Thanks for your detailed explanation. I have already made a PLECS model of simple buck converter using GAN based HEMTS and for since i need synchronas rectification so instead of diode i used GAN HEMT too. I dont know how i can regulate the output of converter

#### Papabravo

Joined Feb 24, 2006
18,457
Thanks for your detailed explanation. I have already made a PLECS model of simple buck converter using GAN based HEMTS and for since i need synchronas rectification so instead of diode i used GAN HEMT too. I dont know how i can regulate the output of converter
You can attempt to regulate the voltage, but regulating the peak current has some advantages in reducing the order of the control loop. A good textbook will explain these matters.

#### LowQCab

Joined Nov 6, 2012
2,060
City-Transit-Buses have had Step-Down Converters for ~60-years,
they weigh about ~50-pounds, for a reason.

I wanna see that Inductor with the 4-gauge Windings !!!
It would make a good Boat-Anchor.

But seriously .........
Why are You using any device that draws almost ~100-Amps at ~12-Volts ?????
And, why the sloppy Voltage Regulation of 9 to 17-Volts ???
Get a 48-Volt device, or preferably, a 120-Volt Device.
High-Voltages are much easier to deal with than High-Currents are.
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