Fusible input resistor in SMD?
Dear support team,
my company is designing a product which will use your LNK302 IC.
As we never did AC/DC designs, we are having trouble finding fusible resistors for input protection in SMD.
I've searched through all of your reference designs and all of them use THT resistor.
Can you please recommend a supplier of SMD fusible/flameproof resistors which will meet the safety criteria.
Best regards,
Ivan
Comments
Hi, I appreciate your answer!
What I knew from before, and what you can see on the link you provided is that SMD variants are only low wattage, i.e. 0.25W, but 1W is recommended in the LNK30X Design Guide. I presume this is due to surge immunity, i.e. 2kV 8/20us as tested here in the EU. Can you please confirm that 1W is needed to pass surge immunity tests? Or can I use 0.25W resistor? (the heating from normal operation is well below 0.25W).
Thanks for Posting your question, Please see the below link for Power Rating of 0.5 W to 2.0 W :
http://www.vishay.com/docs/31030/fpp.pdf.
The fusable resistor has to be minimum of 1W as recommended in the design. At 265 Vin during turn on the fusable resistor has to withstand high inrush current. It has to be as per the recommendation.
Regards,
PI-KSAN
Hi, I have selected an 1W THT fusibe resistor as you recommended and built the circuit which works, but I have a problem.
Here is my circuit.
http://i58.tinypic.com/2cehruc.jpg
Since my design is 1W (80mA, 12V) I opted for a resistor PI network for cost and simplicity reason. The 100R resistor is 1210 SMD case with 0.5W power rating. After I toggle the power couple of time it burns and sparks..guess the inrush current is too great.
What would you recommend? 0.5W 100R is recommended as per Application Note AN-37.
Thanks
Thanks for the reply. Did you measure the Insrush current?How much is it going? Calculate the peak power that is flowing through resistor during inrush current time. Make Sure the Resistor that you choose can withstand the Pulse Peak Power rating as per the data sheet. We suggest to use as per previous message to use 1W resistor and also send us the Inrush current waveforms.
Regards,
PI-KSAN
Hi
I would recommend SMD 2512, 1W fusing flat chip resistor from KOA Speer.
please visit http://www.koaspeer.com/products/resistors/surface-mount-resistors/rf73/ and required any help reach me at my skype account ravindra.sinare1802
Hello, I am not sure you can use the flat chip resistor from KOA Speer since the max Withstanding voltage after fusing is only 100V. In application where input Voltage is 230 AC after fusing the voltage accros the fusible resistor can be more than 300 Volt.
Thank you for posting your questions...
Thanks for posting your question into forum and we appreciate for your time patience and apologize for the delayed response. Please try Vishay or Panasonic SMD Fusible resistor. Below is the link for Vishay and it gives clear information of the SMD Fusible Resistor for Power Watt level range:
http://www.vishay.com/resistors-linear/fusible/
Regards,
PI-KSAN