DER 286
Dear Sir/Madam,
We are in a need to develop a LED Driver for 36W, with 30V and 1.2A output. I have read your design for 30V and 1A output using LINKSWITCH-PH (DER-286), but could not increase the current. If some changes are required in DER-286, please provide.
An early response will be highly appreciated.
Thanks and Regards,
Himank Gupta
댓글
Please mention the components with values that need to be changed.
And please mention if the change will effect the other factors like Power factor, efficiency,UVP value, OVP value etc.
Best Regards,
Himank Gupta
we are designing 30W (30V,1A) following DER286 (capacitor design) ,
but when we short 2 output pin, the IC does not shutdown to protect LED load, the output current is still=3A. all components value are same and in DER286.
any expert can advise reason and solution for the short-circuit problem.
Sir please reply, I am waiting for your response.
You can reduce the FB current upto 85 uA from typical 150uA, and the output current will go up as you reduce the feedback current.
Measure the bias voltage and calculate the feedback current with the 2.5V feedback voltage. You can see how much you can reduce the feedback current and increase the output current.
Sir,
Thank you for your response, I will check it.
Is there a method to add a soft start feature in the circuit.
Can you please send the circuit diagram in which I could have this feature.
Sir,
Thank you for your response, I will check it.
Is there a method to add a soft start feature in the circuit.
Can you please send the circuit diagram in which I could have this feature
There is soft start feature in the LNKPH device as mention in the LNKPH datasheet;
Soft-Start
The controller includes a soft-start timing feature which inhibits
the auto-restart protection feature for the soft-start period (tSOFT)
to distinguish start-up into a fault (short-circuit) from a large
output capacitor. At start-up the LinkSwitch-PH clamps the
maximum duty cycle to reduce the output power. The total
soft-start period is tSOFT.
Sir, will increasing the R10 resistance decrease the feedback current.
You are right.
You need to increase the FB current to increase the output current.
The maximum FB current is 220uA.
Sir,
Please make it clear that to increase the output current, do I need to increase or decrease the feedback current?
And wouldn't it effect the output voltage of the circuit as per datasheet?
And by changing R10, the ratings at BP pin would also change, wouldn't it effect the overall circuit?
You need to increase feedback current to increase output current, and output voltage should be the LED voltage itself.
Thank you Sir for your time.
Your answers were very helpful.
I will let you know, if I need further assistance.
Please mention the components with values that need to be changed.
And please mention if the change will effect the other factors like Power factor, efficiency,UVP value, OVP value etc.
Best Regards,
Himank Gupta