I am working on an LLC converter for a high-end audio system using the HR1001a controller. This week I’ve performed the first tests with a prototype of the final hardware.
During testing, I noticed some discrepancy between the calculated minimum switching frequency and the measured minimum frequency. The measured frequency was about 8.5% lower than calculated. I’ve checked the values of Ct and Rfmin, they were both within 0.5% of the designed value (330pF, 11kOhm)
The maximum switching frequency before bust operation had an even higher discrepancy. often being off by ~20%.
Can you inform me of the tolerance on the oscillator for HR100a? Can the tolerance be improved by using a higher or lower value for Ct?