Power supply with TOP259EN - 120W
Hello,
I am projecting a 120W (12V, 10A)power supply with TOP259EN, I mouted it and I saw some strange behaviour. Firstly, the output voltage increase slowly (5 to 10 secs) to reach 12V. When I use a 300R resistor, it stabilizes in 12V, but when i use a smaller resistor to study its behaviour with high current, it delivers 0,5A max and the voltage becomes zero.
When there is no charge, the voltage is 15~16V.
I did my circuit as shown in the schematic attached.
The R12 and R13 are 56K and 15k2.
Could you help me with this problem?
Best regards,
George Razera
Comments
Hello PI Nano,
It was a problem with the transformer polarisation, now it starts up with no problem very well regulated.
Now the problem is, the max current before my voltage drops to zero is 4A. which components should I take a look?
Best regards,
George Razera
Hi,
I am glad that you were able find out the problem regarding transformer polarity.
Regarding the other problem, Can you capture the control pin voltage, drain current and output voltage together when it is turning off. Also capture the cycle by cycle switching frequency on a zoom in scale.
Can you please send your PIxls/PIExpert design document, Transformer construction document and PCB layout.
Regards,
PI-NANO
Hi i think i have the same problem but the polarity of the transformer is good.
you well find in this document all my results
| Attachment | Size |
|---|---|
| smps.pdf (192.87 KB) | 192.87 KB |
Hi Hicham,
I have answered you question in the following post.
https://ac-dc.power.com/forum/low-power-design/2018/smps-dont-work-0/
Regards,
PI-NANO
thank you PI-NANO
Hi,
Can you please send your PIxls/PIExpert design document, Transformer construction document and PCB layout.
You have mentioned that you have used 300 ohms to stabilize the output voltage, where exactly did you connect the resistor in schematic?
Regards,
PI-NANO