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high current output step dc-dc converter..need help

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john90

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Hi, i need to build a step-up converter which has an input range about 12v to 13.8v. The input needs to be step-up to 18.5/19v. The problem lies with the output current as it must be able to generate a max of 3.5A to the load.

This is for typically laptop purpose.thx.

Any schematics or suggestions?..
 

john90

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ya its from a car light..not sure whether this switcher can do the job.. LM2677
 

blackice504

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well there is enough current handerling.
have you tried to adjust the freq to see what that does?
 

john90

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actually i was thinking whether if solar cells with an input voltage of 12.33-13 and current 4 A could be used on this switcher..

hmm, i had not adjust the frequency..i thought the clock frequency is in the ic chip?..
 

blackice504

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https://www.national.com/pf/LM/LM2677.html

by changing the Freq it changes the speed it can charge the caps thus changing the voltage.

well this is from what i understand i am looking into dc to dc convertors my self i want to get 12volt to 240volt with a current of 100amps

Added after 7 minutes:

it has a sync pin that you can adjust its freq to get a different voltage but as to how that sync pin works i not sure i had a quick look at the PDF but there was not much help on it from my understanding it had a coupling cap this leads me to believe that a external clock was used.
 

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