looking for a dc-dc stepdown/buck circuit with high current output

fabieville · 05-28-11, 12:07 PM

I am looking for a dc-dc stepdown/buck circuit that can handle up to 60VDC max input with an adjustable output or a fixed output of 14VDC and have output current up to 8amp or greater.

Xringer · 05-28-11, 02:19 PM

Buy eight LM317HV ($3 each) chips and put them in parallel.?.

LM317HV - 3-Terminal Adjustable Regulator

Make them all adjustable, so you could carefully set each one to 14.00 volts.

Here's a data sheet..
http://www.national.com/ds/LM/LM117.pdf
page 22 shows a few stacked together..

fabieville · 05-28-11, 11:49 PM

Could i build a buck step down circuit using LM317 or anyone of those adjustable regulators? I am wondering if it would work like how a conventional buck circuit operates. I am planning to use Lm317HV which can take in a very high input and use some lm317HV in parrallel to gain more current output along with a good size inductor in the circuit. So would it work like how a buck circuit operates?

I am trying to acheive more current at the output than what is coming in after the input voltage has been step down. Like how mppt works converting that excess voltage to current. So for eg. if i have 30VDC at 3 amp at the input after stepping down to 14VDC will i have more current at the output maybe twice the amount? Will that be the case?

mejunkhound · 05-31-11, 08:55 PM

more current at the output than what is coming in

was going to suggest the national semiconductor "simple switcher" till you mentioned the 'more current'.

Depending on your electronic capabilities, to get more current you will need to use a step down xfmr and a pwm chip like the UC1846 and a push pull or forward converter topology.

You can get a little more current out than in on a near classical buck circuit if the input voltage is lots higher and you put a big capacitor at the input, but nothing like doubling the current.

cbarbie · 06-03-11, 01:15 PM

Have you tried looking at a solar charge controller that has a stepdown function?

cbarbie · 06-03-11, 01:19 PM

Here is a list of some DC-DC converters that are available:

DC%20to%20DC%20Voltage%20Converters%20-%20DIY%20Solar%20Panels%20&%20Renewable%20Energy%2 0@%20AltE%20Store]DC to DC Voltage Converters - DIY Solar Panels & Renewable Energy @ AltE Store

It looks like there may be a couple that might fit your needs.

If not, here is a list of solar charge controllers and some of them have a stepdown function.

MPPT charge controllers for solar panels systems @ AltE Store

I am not pitching this vendor, they just have a large selection.

05-28-11, 12:07 PM	#1
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	looking for a dc-dc stepdown/buck circuit with high current output I am looking for a dc-dc stepdown/buck circuit that can handle up to 60VDC max input with an adjustable output or a fixed output of 14VDC and have output current up to 8amp or greater.

06-03-11, 01:15 PM	#5
cbarbie Lurking Renovator Join Date: Mar 2010 Posts: 7 Thanks: 0 Thanked 3 Times in 1 Post	DC-DC converters Have you tried looking at a solar charge controller that has a stepdown function?

05-28-11, 02:19 PM	#2
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Buy eight LM317HV ($3 each) chips and put them in parallel.?. LM317HV - 3-Terminal Adjustable Regulator Make them all adjustable, so you could carefully set each one to 14.00 volts. Here's a data sheet.. http://www.national.com/ds/LM/LM117.pdf page 22 shows a few stacked together..

05-28-11, 11:49 PM	#3
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	Could i build a buck step down circuit using LM317 or anyone of those adjustable regulators? I am wondering if it would work like how a conventional buck circuit operates. I am planning to use Lm317HV which can take in a very high input and use some lm317HV in parrallel to gain more current output along with a good size inductor in the circuit. So would it work like how a buck circuit operates? I am trying to acheive more current at the output than what is coming in after the input voltage has been step down. Like how mppt works converting that excess voltage to current. So for eg. if i have 30VDC at 3 amp at the input after stepping down to 14VDC will i have more current at the output maybe twice the amount? Will that be the case?

05-31-11, 08:55 PM	#4
mejunkhound Apprentice EcoRenovator Join Date: Apr 2011 Location: PNW Posts: 197 Thanks: 0 Thanked 47 Times in 31 Posts	more current at the output than what is coming in was going to suggest the national semiconductor "simple switcher" till you mentioned the 'more current'. Depending on your electronic capabilities, to get more current you will need to use a step down xfmr and a pwm chip like the UC1846 and a push pull or forward converter topology. You can get a little more current out than in on a near classical buck circuit if the input voltage is lots higher and you put a big capacitor at the input, but nothing like doubling the current.

06-03-11, 01:19 PM	#6
cbarbie Lurking Renovator Join Date: Mar 2010 Posts: 7 Thanks: 0 Thanked 3 Times in 1 Post	Here is a list of some DC-DC converters that are available: DC%20to%20DC%20Voltage%20Converters%20-%20DIY%20Solar%20Panels%20&%20Renewable%20Energy%2 0@%20AltE%20Store]DC to DC Voltage Converters - DIY Solar Panels & Renewable Energy @ AltE Store It looks like there may be a couple that might fit your needs. If not, here is a list of solar charge controllers and some of them have a stepdown function. MPPT charge controllers for solar panels systems @ AltE Store I am not pitching this vendor, they just have a large selection.