Fuse instead fusible resistor? LNK306 buck 230V->5V/250mA:
Hi,
My design is typical diagram from AN for LNK306 (attached as a picture to this post).
The conversion is 230V+/-15% into 5V 250mA in buck topology.
Questions :
1) Can I put a fuse instead fusible resistor in front of it?
Fusible resistors are hard to buy and more difficult to replace.
2) What rated current and speed should I use (eg 250mA super quick acting) ?
3) In PIXls: is "Input Stage Resistance, Fuse & Filtering"
equal to a fuse resistance if a diagram is directly from AN (see a picture attached)
Wojtech
Comments
Hi Terry,
thank you very much for your reply.
After your detailed comment I consider to use a fusible resistor again...
How to obtain its value to protect rectifiers from inrush current?
PIxls does not calculate any value of it , an "Input Stage Resistance" cell remains empty until a user puts his own value into an input data cell.
CU2/2 for diodes?
Hi,
The resistor value will be based on the rectrifier bridge you are using. There is a parameter of maximum peak current for the bridge, you will have to select the resistor value to limit the current to be less than the peak current during start up.
Hi, here isthe comments regarding your questions:
1. A fusible resistor has two fuctions: fuse and inrush current limiation during startup. If you want to use a fuse, you should add an addtional inrush current limiation components, it could be a thermistor (NCT).
2. To choose the fuse, the rated current should be at least two times of the average input current. And the I2T should be able to support the inrush current during start up: I2t>=C*(Vin_max*1.414)2/2.
3. What is the question?