Trying with 5v input from USB into a pretty standard circuit using LM2577S-ADJ to get 60v

After changing a lot of components, all I can get as output is 54.4v

Is this the max voltage output you can get out with such a low input voltage.



I have tried input caps 100uf and 220uf, inductor 100uH and 330uH, output caps 1000uF with 1uF poly.

Only using 1 half of MBRF10100CT
• 100 V, 10 A dual Schottky (5 A per leg)
• Trench MOS Schottky technology
• Vf ≈ 0.75 V @ 5 A, lower at light current
• Very low switching loss

Has made no difference.

Any ideas or suggestions.

Or should I try to get the R1 and R2 ratio more accurate (in my case R1=100k + 1k and R2 = 2k2). That is to reduce R2 to 2k11 ?

 

Hi gray,
Extract from d/s.
https://www.google.com/search?q=lm2...nArCBwcwLjMuNS4yyAcogAgB&sclient=gws-wiz-serp
E

 

You are probably being limited by the maximum duty-cycle the chip can generate.
Goggle AI suggest the maximum step-up ratio for typical circuits is about 10:1 (i.e. 50V for a 5V input).

So for higher voltages you could go to a flyback converter configuration with a transformer, or use two boost converters in series.

 

or use two boost converters in series.

I have never seen that done, but it sounds ideal.

I suppose you could get a split voltage supply then, say +15v 0v -15v

 

I have never seen that done, but it sounds ideal.

I suppose you could get a split voltage supply then, say +15v 0v -15v

I was thinking about the first boosting 5V to about 20V and then the second boosting that 20 V to 60V.