LM3402 showing unusual response

Hello,

I am creating an LED driver using LM3402HV. When I connect the circuit as shown in attached datasheet, it shows unusual response.

When I connect the R(ON) resistor to pin 7 and then measure the voltage on PIN 8, it reduces to 7V from 40V. My VIN voltage is 40V. My requirement is 36V/480mA. What I need to do to maintain the Vin at 36V on this pin? The value of Ron is 220K. I am driving a strip of 96 LEDs. 12 in series and 8 columns of 12 series connected LEDs in parallel. Do I need a higher capacity power supply?

I have created whole Circuit but at the output, I am getting only 5V. What to do?

Then I disconnected all the parts and one by one, I checked all the components and its voltage, then the problem is same as before. Why the voltage is getting down? Is there any problem in this design? Do I need to increase the input voltage?

Please help me to solve this issue.

Thanks.
Chirag

Hi,

measure the voltage on PIN 8, it reduces to 7V from 40V. My VIN voltage is 40V.

Click to expand...

Pin8 is V_In voltage, how can it be it reduces to 7V when you say your input voltage is 40V?

In doubt connect a 200k resistor between pin8 (V_in) and pin6 (RON) as recommended in the datasheet.

This circuit is not suited for a breadboard.

Klaus

Hello,

I have achieved the voltage by changing the R(ON) resistor. I have obtained 32V at output. But when I tried to connect LED Tubelight, it did not worked.

Here is the complete schematic of my circuit. Please help me to solve this issue.

Thanks.
Chirag

- - - Updated - - -

The resistor I have changed to R(On) is of 330k. Please ignore 59k in schematic.

- - - Updated - - -

Yes, I have done one test. I have supplied the rectified DC voltage. It is 40V. But still its not working. My tubelight is having 105 LEDs in strip. I think the current is not sufficient for this because the LED glows with very poor intensity. Its too low so I think I need higher current source. Even though I need suggestions from you guys.

Thanks.
Chirag