你們都是如何做 DC/DC 的 system simulation?

happybull

PFM works at light load and converter is in DISCONTINIUE. That means the feedback loop is BROKEN. So it is unconditional stable.

happybull

Some IC softstart consume a spike current. If you set your powersupply current limit low, power supply output will be pull down by the IC  startup transient current


(5)以前我用FAN4855 PFM boost converter ,發生有時FAN4855上電源後 ,電源供應器之output被拉low; Q. Z7 W+ z6 h$ c- o
而造成PFM output voltage不正常
但 電源供應器之output current 已設定
大於PFM   boost converter power on initial 時
或  PFM boost converter steady state 時 所吃之current
且電源供應器之output voltage 已設定為大於PFM  IC's  Vin,minimum)

[ 本帖最後由 sjhor 於 2007-11-12 09:02 AM 編輯 ]

happybull

The answer is NO.
I think the output PAD you mentioned is LX pad. The LX PAD is always protected by power N or PMos it self. (99% ICs )