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Original question:

UC2843: What is relation between V-sense and Ouput Duty cycle ?

UC2843: UC2843

sachin Godse
Prodigy 10 points
Part Number: UC2843

Hello ,

I have getting issue with output PWM duty cycle.

Even though I have given constant input at pin no 3 (Isense)  Output PWM continuously vary, and flickering observed  

Same solution I have used for different circuit it's working fine 

  • 0
    TI__Mastermind 29805 points

    Pin 3 is FB but you mention a constant input at pin 3 (ISENSE) - please clarify. Also, what is "constant input" at pin3....AC, DC, level, frequency?

    Regards,

    Steve

  • 0 in reply to Steven Mappus1
    Prodigy 10 points

    I'm providing 1.2V to 0.1V (variable DC voltage) at pin 3 to generate 0% to 100% duty cycle respectively.

    It was observed when I vary the input voltage from 1.2V to 0.5V it was given me proper respective duty cycle (Roughly start from 0% and maximum is 60%) but when I reduce voltage below 0.5V then output duty cycle (Duty cycle from 60% to 90%) start flickering (Continuously vary).

  • 0 in reply to sachin Godse
    TI__Mastermind 29805 points

    Sachin,

    To do this open loop test, from a closed loop, remove the feedback, connect FB pin to GND and connect a resistor from COMP to GND and fixed duty cycle is obtained. To vary your desired duty, adjust that resistor value from COMP to GND. If open COMP, max duty can be obtained. 

    Steve