HF500-30 Rsense value determination

AC-DC Power Converters
1

I am planning to use HF500-30 IC in one of my design. How to determine the Rsense value on source pin.

2

A post was merged into an existing topic: About the AC-DC Power Converters category

4

For calculating Rsense, first you need to calculate the Ton (equations 7 and 8 in datasheet) . Then use Sramp (given on page 6 of datasheet) as 25mV/V and please use VILIM as 1V ( on page 6 of Datasheet) . The according to equation 14 , Vsense = 0.95VILIM – ( Sramp* Ton) . Then use equation 8 and 9 to calculate Ipeak. Assume Kp=0.8. Now you have calculated Vsense and Ipeak. Use that to calculate Rsense using equation 15 which is Rsense = Vsense/Ipeak.

5

Hi Akumar:

Typo correction: Sramp is 25mV/usecs. Since the units of Sramp are in millivolts per microseconds, please be sure to calculate Ton in microseconds to the keep the integrity of units (dimensions). Also I would encourage you to do worst case calculations at min and max of all the datasheet values and not just at nominal or typical value.

6

HI Mr.Kumar:

Received your schematic but no BOM or Transformer datasheet. I will need that also.