# Can I buck High Voltage Low Current to Low Voltage Higher Current?

Thread Starter

#### Khaleef

Joined Mar 22, 2017
76
Hi AACians

Been looking at Buck converters for a while and been thinking.

I need a particular voltage and current for an application. But I found some good units with ratings higher than voltage I need but lower in required current. Can one achieve the current by using a buck Converter?

For example, I need 6v/12v with like 8/10A. With a 10amp rated Buck converter, can I buck 36V/2A to achieve my desired voltage and current?

Thanks.

#### AlbertHall

Joined Jun 4, 2014
11,127
The efficiency of the buck converter, on a good day, might be around 90%. So if your input is 36V/2A, that is 72W then the maximum output will be 0.9 * 72W = 64.8W. If the output current is 10A then the maximum voltage you can get is 64.8W / 10A = 6.48V. If the output current is less than 10A then you could get a higher voltage.

• Khaleef

#### Papabravo

Joined Feb 24, 2006
15,515
The immutable law of DC-DC converters is:

Power_Out < Power_In;

sometimes it is much less

Last edited:

#### mvas

Joined Jun 19, 2017
538
You can obtain 90% efficiency (typical) by using a Synchronous Buck converter
A really good Synchronous Buck converter can obtain 95% efficiency

an example of 90% efficiency = LT1339 Synchronous Buck Converter = 25 V Input, 5 V Output at 10 Amps ...
https://www.analog.com/en/products/lt1339.html

Input: 36 Volts x 2 Amps = 72 Watts

64.8 Watts Output = 72 Watts Input x 90% efficiency

Output: 6 Volts @ 10.8 Amps = 64.8 Watts
Output 12 Volts @ 5.4 Amps = 64.8 Watts

Last edited:
• Khaleef
Thread Starter

#### Khaleef

Joined Mar 22, 2017
76
Thank you so much @mvas @AlbertHall

Very perfectly explained there. Now I know what I need to solve my problem. 