TOP265KG-TL can work on 19.2 Vdc input??
Our team is designing SMPS
Input DC : 19.2 - 373 Volt & universal AC voltage range
output : 12V , 5W
We have previous design of 3W output, Which is working fine in above input range (primary inductance 240uH). This design we are modifying for 12V, 5W. Here V pin shorted to GND. X pin is connected to 12K. Here we have used TOP265KG-TL.
3W design we are tested for 5W. For above voltage range , Below are the observations:
- For DC 19.2V, It is not starting. It is going in Auto-restart mode
- above DC 25V, it is working fine and delivering 5W power to load.
Question:
- Can it work on 19.2Volt DC?
- For this requirement, can you suggest any other switch??
Comments
Thanks for fast response. All above points are noted. In spreadsheet, 10mF input capacitor seems problem. It will completely change form factor of 3W design.
Do you have any other way to solve this issue in previous 3w design ?
Do you have any other Power integratio IC for solution?
If you required any other information, please let me know.
That 10000uF capacitor is only in place in the spreadsheet as a trick to approximate a DC source. If you use a true DC source, it will not be needed. If you are generating the DC using rectified AC mains, you have a problem, as with any reasonably sized bulk capacitor, the trough voltage will dip too low and the TOPSwitch will lose regulation due to duty cycle limit and likely go into auto-restart.
I just ran the design spreadsheet using a bulk capacitance of 150uF and 60Hz mains frequency, and the trough voltage goes down to only 5V - bad news.
There are several reasons for operation in auto-restart 1) the part is duty cycle limiting 2) the transformer VOR is not low enough, which would also cause the duty cycle issue. I am attaching a spreadsheet for a design that might meet your needs. Ignore the input parameters for the most part - I had to trick the spreadsheet to make the rectified input voltage approximate a DC source.