Issues with LNK304DN
Hello,
I'm using LNK304DN in a buck topology. Schematic is attached.
Vin = 85-264V
Vout=16,5V
Iout=115mA
Converter works fine from approx 120VAC to 264VAC.
At lower input voltages from 90-120VAC and at higher ambient temperature 50°C or more, sometimes nonproper beahaviour could occure.
Output voltage starts to shutnig off to 0V and restarting automaticly. If input voltage is increased to 130VAC or more LNK starts to operate without this issues.
It seems like the output is overloaded or someting like that?
Is it possible that thermal margin is to small?
Is it possible that output capability of LNK become lower with higher ambient temperature?
Than you for your support
Files
| Attachment | Size |
|---|---|
| LNK304DN.jpg | 137 KB |
Comments
Hi Miha,
Can you send your PCB layout? LNK304 needs enough copper plane connected to the SOURCE pin to dissipate the heat.
Add a bias resistor between C51 (+ side) and BP pin. This will improve efficiency and reduce the IC losses.
For a 16V output reference design, please refer to DER-845
https://ac-dc.power.com/sites/default/files/product_document/design_example/der-845_4pt8watt_non-isolated_buck_converter_using-900v_linkswitch-…
Any idea, what could be the problem?