txbob
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Hi,
In one of the existing design I was working (pfc boost with UCC2818D controller) , I noticed that soft start is implemented by pulling the voltage error amplifier down through a diode (which will make multiplier output to zero) as shown in blue lines. This is done during startup and also some transient events when the boost duty cycle needs to be drastically reduced
The uc2818 does have a dedicated soft start pin which can be activated by OVP/EN pin (Pinno:10) but for some reason initial designer didn’t use that feature for enabling soft start, may be the duty cycle will not go down all the way to zero….
My question is there anything wrong pulling down on error amp output ? The datasheet is not saying that it is a transconductance amplifier.
https://www.ti.com.cn/cn/lit/ds/symlink/ucc3817.pdf
In one of the existing design I was working (pfc boost with UCC2818D controller) , I noticed that soft start is implemented by pulling the voltage error amplifier down through a diode (which will make multiplier output to zero) as shown in blue lines. This is done during startup and also some transient events when the boost duty cycle needs to be drastically reduced
The uc2818 does have a dedicated soft start pin which can be activated by OVP/EN pin (Pinno:10) but for some reason initial designer didn’t use that feature for enabling soft start, may be the duty cycle will not go down all the way to zero….
My question is there anything wrong pulling down on error amp output ? The datasheet is not saying that it is a transconductance amplifier.
https://www.ti.com.cn/cn/lit/ds/symlink/ucc3817.pdf