how to get wide range of input AC voltage operating range of a SMPS

[muraliuvce]

Hi,

i am Murali Krishna new to Real time work i am trying to develop a 150W LED driver, I have a reference design for "Power Integrations " i.e RDR 291. its operating input voltage is (184-275)v AC but i want to make it (90-265)V AC, so can anyone suggest me what hardware changes makes me get those operating range. here is the attachment please go through it and find me some solution.

 

[Genovator]

Its hard to modify this design as all designs are made for some specific purpose. You need to change your 'control IC' so that it can easily allow 90V to be converted to 33V. That IC senses input voltage and response to that, produces PWM, which produces constant output. It works for the range 180V to 300V. See the following link and choose the specific IC for your need....
**broken link removed**

Also refer and compare the datasheet of the IC for correct calibration.

 

[Orson Cart]

You will need to go to a TOP250 to get enough power and peak current rating to allow wide range operation, also bigger transformers...

 

[muraliuvce]

can i change the output current from 2.1A to 2.7A by increasing the Feedback pin Resistor value? the actual output current is 2.1A and the feedback resistance value in the design is 95.3 K ohm . can i increase the Resistor value to 110 K ohms or higher to get the output current 2.7 A.

 

[muraliuvce]

Its hard to modify this design as all designs are made for some specific purpose. You need to change your 'control IC' so that it can easily allow 90V to be converted to 33V. That IC senses input voltage and response to that, produces PWM, which produces constant output. It works for the range 180V to 300V. See the following link and choose the specific IC for your need....
**broken link removed**

Also refer and compare the datasheet of the IC for correct calibration.

can i change the output current from 2.1A to 2.7A by increasing the Feedback pin Resistor value? the actual output current is 2.1A and the feedback resistance value in the design is 95.3 K ohm . can i increase the Resistor value to 110 K ohms or higher to get the output current 2.7 A.

And Can you relate output current and feedback resistance value either it is proportional or inverse proportional ?

 

[Genovator]

can i change the output current from 2.1A to 2.7A by increasing the Feedback pin Resistor value? the actual output current is 2.1A and the feedback resistance value in the design is 95.3 K ohm . can i increase the Resistor value to 110 K ohms or higher to get the output current 2.7 A.

The output current has nothing to do with the feedback pin. If you read the datasheet you can see that it is written- "The current into the FEEDBACK pin is directly proportional to the output voltage." Thus, if you increase the resistance
in FEEDBACK pin, it will decrease the current flowing to it, thus the output voltage will drop.

However, the control IC LNK420 is designed to give a power output of max 75W. So you have to first count up- what current you need at what voltage? Look to the schematic design in the SMPS document and compare it with the datasheet. The maximum output power is achieved when Rv value is 4M ohm. In the SMPS design, they connected R5, R6 & R7 in series with values of 1M, 1M & 2M ohm respectively. That is, they are using the IC with its fullest capacity.

You can increase the current output a little by reducing the output voltage. But the matter will be same. It is always recommended to use such devices to 80% efficiency only.

And Can you relate output current and feedback resistance value either it is proportional or inverse proportional ?

Now, I should say that the output voltage is inversely proportional to the feedback resistance.