Current Question - Electronic Circuits Projects Diagrams Free

johnsz · 22nd February 2003, 01:39 AM

OK, I have a silly question but I'm sure so one can answer the question for me.

I'm trying to make a DC-DC comverter with an Input of 34VDC rated at 2 amps, and I'm thinking of bringing that down to 5VDC. My question is that would I only still have a maximum current of 2 amps or since my voltage went down will my current go up? I'm thinking of using an LM340 or somthing simular.

Thanks in Advance.

John

Sebi · 22nd February 2003, 06:54 AM

When You apply a dissipative regulator as LM340, the current of output equal to input. If the input voltage is 34V, output 5V, the difference 29V,multiple with 2A load = 58W dissipation (heat on LM340).
With switching regulator from 34V 2A input You can suck from output about 6A.

johnsz · 22nd February 2003, 01:17 PM

I appriciate your response. What component or design would you recommend? I'm trying to keep it as simple as possible, If thats possible.

John

pebe · 22nd February 2003, 08:56 PM

This is the link to a japanese switched mode power supply. It can deliver 5V at up to 2.5A from a supply of between 7 and 40VDC.

http://www.interq.or.jp/japan/se-inoue/e_ckt22.htm

It uses a switched mode chip and just a few other bits, so efficiency is at a max and surplus heat at a minimum.

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22nd February 2003, 01:39 AM	(permalink)
johnsz	Current Question OK, I have a silly question but I'm sure so one can answer the question for me. I'm trying to make a DC-DC comverter with an Input of 34VDC rated at 2 amps, and I'm thinking of bringing that down to 5VDC. My question is that would I only still have a maximum current of 2 amps or since my voltage went down will my current go up? I'm thinking of using an LM340 or somthing simular. Thanks in Advance. John

22nd February 2003, 06:54 AM	(permalink)
Sebi	When You apply a dissipative regulator as LM340, the current of output equal to input. If the input voltage is 34V, output 5V, the difference 29V,multiple with 2A load = 58W dissipation (heat on LM340). With switching regulator from 34V 2A input You can suck from output about 6A.

22nd February 2003, 01:17 PM	(permalink)
johnsz	Recommended Component I appriciate your response. What component or design would you recommend? I'm trying to keep it as simple as possible, If thats possible. John

22nd February 2003, 08:56 PM	(permalink)
pebe	This is the link to a japanese switched mode power supply. It can deliver 5V at up to 2.5A from a supply of between 7 and 40VDC. http://www.interq.or.jp/japan/se-inoue/e_ckt22.htm It uses a switched mode chip and just a few other bits, so efficiency is at a max and surplus heat at a minimum.