UC3525A: UC3525A

Hi,

CT=1.5n, RT =4.22k, RD = 0, my result = 204.9kHz, instead of yours 226kHz.

I used excel sheet and first verified the below. Please verify your calculation first. Then I think you need to verify your CT, what is its type, its voltage rating, its tolerance, etc. It is likely CT you used has 15% tolerance, RT has 1% or 2% tolerance, IC has up to 13% tolerance. To get 6%, you need to have CT and RT measured accurately to know what their values are and not relying on their nominal values, then IC tolerance can be kept < 6% if you can keep temperature at 25C, and keep voltage tolerance at about 1 to 2%, the resulted f is the most accurate result you can get.

Thanks Huang for your reply.

I think you are calculating using the formula with RD=100 Ohm. RD=0 ohm in my case, since the pins 7 and 5 are tied together in the application circuit that we have been using. FYI, CT tolerance is 5% and RT tolerance is 1%. Where did you get 13% tolerance of IC from?

Regards,

Hi,

My calculation is based on your parameter values. Please check your calculations which look to me are wrong.

See the below table, there are three tolerances, add them together its worst case 14%.

You need to measure your CT. What type of capacitor are you using. usually 10% tolerance is already at its best for a capacitor, so curious what makes your capacitor 5% tolerance, did you measure its value and at what voltage?

Hi,

I am closing this as you are using a private to communicate.