problem with DC POWER

Thread Starter

dspcan

Joined Dec 16, 2007
6
Dear sir,
I want to make such DC power:
input volt range:18v-70v
output volt:5V
maximum current:5A
I cant't find such power chip to meet the requirements, someone have any ideas? I have been told to build the circuit by 7805+transistors+zenr dioder,but I don't know how to build it.
thank you for your consideration
 

hgmjr

Joined Jan 28, 2005
9,029
Based on your maximum output power requirements of 25 Watts and the large input voltage range, I would think the 7805 linear regulator would not be the most efficient way to go.

A better approach would be to use a switched mode power supply. Perhaps one of the National Semiconductor Simple Switchers would be valid choice. You can go to www.national.com and do a little research.

hgmjr
 

hgmjr

Joined Jan 28, 2005
9,029
Upon a little more research into my suggestion to use a member of the National Semiconductor SimpleSwitcher series as the basis for a solution, I discovered that the maximum input voltage that was recommended for the specific devices I had in mind is limited to 45 volts. This means that a pre-regulation scheme would need to be arranged to prevent the input of the SimpleSwitcher from seeing any input voltages greater that 45 volts.

hgmjr
 

Thread Starter

dspcan

Joined Dec 16, 2007
6
in the attatched file. if the parameters of parts are arranged carefully ,I think the circuit can work normally for liner regulator/switcher or power module.
 

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