Fly back power supply design
Posted by: Yasin
on
we require a charger circuit with 0.8A output current and 8v output voltage at 230V input. The circuit diagram of 0.4A and 8V output is attached. Can you please suggest how can we increase the output current to 0.8A. What resistance values are required.
Files
| Attachment | サイズ |
|---|---|
| Schematic.pdf | 21.54 KB |
Hello Yasin,
There is no magic resistor you can change to increase the maximum output current capabilities. Do not despair! There is a useless piece of document we are calling "Product Data Sheet" located here:
http://www.powerint.com/sites/default/files/PDFFiles/tny264_266_268.pdf
What you need is this paragraph:
TinySwitch-II Operation
TinySwitch-II devices operate in the current limit mode. When enabled, the oscillator turns the power MOSFET on at the beginning of each cycle. The MOSFET is turned off when the current ramps up to the current limit or when the DCMAX limit is reached. As the highest current limit level and frequency of a TinySwitch-II design are constant, the power delivered to the load is proportional to the primary inductance of the transformer and peak primary current squared. Hence, designing the supply involves calculating the primary inductance of the transformer for the maximum output power required. If the TinySwitch-II is appropriately chosen for the power level, the current in the calculated inductance will ramp up to current limit before the DCMAX limit is reached.
We provide free tools to help you with this transformer design task.
Cheers,
PI_Crusher