Part Number:UCC256302
Hi Sir
we have above questions need your help, pls help to check it,tks!
(1)VCR Pin：
The corresponding definition is not found in the Icomp specification in the following formula. Is it consistent with the definition of Iramp as follows?
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(2).This IC specification is defined as the operating frequency range 35KHZ-1MHZ;
Is it possible to set the maximum and minimum operating frequency separately? The current test boot frequency is 700KHZ.
(3)Soft start
At present, the Css capacitor is 0.22uF, and the actual test soft start time Tss is only 22ms, which does not correspond to the actual calculated value.
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(4)At present, the integrated transformer is used. Parameters: transformer leakage inductance 52uH, inductance 480uH. Resonant capacitor 824. SS pin capacitance 0.22u. RVCC-SS pin divider resistor 750K/200K, VCR voltage divider detection capacitor 101/222, ISNS current sense RC Parameter 100PF/255R, BLK setting 340V start. BW pin is not connected. Vcc is set to no load 15V. At present, the normal working frequency of the prototype is idling at 60K, the output voltage is set to 5V, and the actual value is 4.5V. The load will drop. Please help us to see if there is any unreasonable or need to adjust?
