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UC2843A: Driving the comp pin directly

Part Number: UC2843A

Hi Team,

Our customer would like to confirm if it is possible to defeat the internal error amplifier by driving the comp pin directly. According to him, there is a legacy design that uses that technique and he was curious if it is a recommended method of bypassing the internal error amplifier. Additionally he would like to ask the following questions:

1. What is the tolerance of the 1V clamp on the non-inverting input of the current sense comparator?

2. What is the tolerance of the 2R/R divider network that is also attached to the non-inverting input of the current sense comparator?



  • Hi Danilo,

    It is not recommended to drive the COMP pin directly. COMP is low impedance and very noise sensitive. As far as the tolerance of the internal 1V clamp and the R/2R divider, these are not measured parameters but a fair estimate can be had by considering the variation of the CS input which is the non-inverting pin to the CS comparator (the 1V clamp and resistive divider are the inverting input to the PWM comparator). This is given as 1V ±10% in the data sheet.


    Steve M