LNK304 for 95-305 VAC application

Hi Micro Design,

Good day.  Thank you for choosing Power Integrations' part.

Regarding your question, the LNK304 can work up to 305 VAC especially it is a buck topology and it has 700V rated MOSFET.  You only have <450V stress at your MOSFET at 305 VAC input.  

You can use that but I will recommend you to use newly released Linkswitch-TN2.  It is the improved version of the Linkswitch-TN that your are planning to use.  They are pin to pin compatible with improvements like higher MOSFET rating of 725V and better regulation performance.  See below link for your reference.  Good luck on your design and I think you won't have problem with your US agency approvals.

https://ac-dc.power.com/products/linkswitch-family/linkswitch-tn2/

Would you recommend direct feedback or optocoupler feedback for the load current range of 1 to 100 mA?

Thanks

Feedback depends on your requirement.  For direct feedback it is cheaper solution but with more parts.  It needs preload to maintain regulation at no load condition.  But since your minimum load is 1mA, you can remove preload.  If you don't have preload resistor and you remove your 1mA minimum load, your output regulation will increase around 5-10%.  If that is not acceptable to you, maintain your resistor preload.    

Hi Sir,

Have a great day..

Is there any provision to design a 5V power supply for 8051 microcontroller by using LNK TN family IC?

Hi Mithun PV

Yes definitely you can design with 5V output with LNK-TN.  For microcontroller supply which needs good regulation, you need to put a post linear regulator which has 5V output in your case.  You have to design you LNK-TN higher than 5V for post regulator input margin.  Thanks.

Hi,

Does the Linkswitch-TN2 are meant to replace the Linkswitch-TN ?

Will the LinkSwitch-TN be discontinued ?

hI St7ven,

The Linkswitch-TN will still be available to support your existing and future product productions.  It is still has alot of customers to support so it will not be discontinued.  If you already have the existing working design with Linkswitch-TN, you don't have to worry since we will support the demand of your products until the end of your product's life.  

Linkswitch-TN2 is released just recently with improved performance compared to Linkswitch-TN so we recommend the TN2 for new design development.  It has same simplistic design approach and it is pin to pin equivalent but not direct replacement for existing TN design.  It will work but regulation and power capability will change.  Linkswitch TN2 has better efficiency, higher power capability, better ripple, better surge handling capability with increase MOSFET rating to 725V from 700V of Link-TN.

Thank your for using Power Integrations' part and as part of our commitment to our customers, we continue to improve our products and give you the best available controller with continuous improvement in technology.

Hi,

It seems to me that the layout are the same and only the feedback and bypass resistor have to be adjusted. So only those changes need to be done in order to shift from the Lnk306 to the lnk3206, is that correct ?

Hi St7ven,

That is correct.  Those are the only thing you need to change shifting from Lnk306 to Lnk3206.  

Is there any provision to get dual output (5v and 12v at the same time) by using TN Linkswitch IC?  If it is possible kindly help us with suitable Schematic design? Is it possible dual output(5v and 12v) by using 5V Zener instead of 3.9V Zener reference to the attached file?

Hi Mithun PV

Thank you for using Power Integrations' part.

Regarding your question, you can definitely do that.  You must have your base voltage Vb higher than your Emitter Voltage Vee (5V output) by atleast Vbe voltage which is typically 0.7V so you need atleast 5.7 Zener voltage.  You now compute your bias resistors for base current and collector current for your output current specs.  

Hi

Thnx in advance

Pls give me more details of above ur valuable commands,

so how we calculate the R8, R7, R4, R5 values with 5.7V zener to get a 5V out ,,  pls note the schematics below

Hi Mithun P V,

Those components are actually discrete linear regulator.  You can just replaced the VR1 with 5.7V zener then see if you have 5V output.  If you needs to fine tune the output voltage, adjust R8 lower if you need to reduce regulation or higher if you needs to increase.  R5 is just pre-load.  Thanks.