problems with supply 5V-2A using tny277
Hello, I designed a source to 5V/2A PIexpert8. The device used is tny277. The PI Expert design and layout of the circuit are below.
The problem I have is that I can not reach the maximum current of 2A. Above 0.4 A the TNY off.
for the construction of the transformer design followed exactly PIexpert, measuring the inductance with a common Inductimeter I have here and the values were very close.
What can be the problem?
thank you
heeding: The second file is the PIexpert to open it change the extension. PDF for. UDS
Comments
thank you, I realized that was a reversal of polarity of the secondary winding. Now I have the 2A, but had to increase the inductance of 763uH to 1200uH. Is this normal? doubt if my Inductimeter is reliable, can you indicate some Inductimeter reliable? the circuit is working now but I am wondering the extent of 40% efficiency, installed at the inlet to measure a true rms ammeter, which is they are doing something wrong?
If PI Expert suggested 763 uH, then is should work with that inductance. You will need to troubleshoot the power supply. Start with looking at the drain voltage and current with a scope. This gives a great deal of insight to the operation of the power supply.
Z. Cochrane
If the primary inductance is OK then check that the phasing of the transformer windings are correct. If this is correct, you will need to measure the drain current and drain voltage with a scope. Send me the scope pictures if you need additional help.
Z. Cochrane