■ 概要
AS3505K系列是基于CMOS工藝的輸出電流為1A*的低消費電流的同步整流型降壓DC/DC轉換器。
該芯片由振蕩器，電壓基準源，誤差放大器，開關控制電路，模式控制電路，軟啟動電路，鎖定保護電路，欠壓鎖定電路(UVLO)，過熱關斷電路及開關晶體管等組成。這塊芯片采用開關器件內置的同步整流的方式，加電感和電容即可構成一個率的降壓DC/DC轉換器.由于封裝為DFN(PLP)2020−8，因此芯片適用于板級高密度貼裝。
AS3505K系列包含，通過內建的反饋電阻網絡以0.1V的步長，&plun;1.5%或18mV的設置輸出電壓的IC內部固定類型(A,B版本)以及可通過外接電阻網絡決定輸出電壓的可變類型(C版本)。
另外，可以通過MODE引腳選擇不同的工作模式，在輕負載時能自動切換至率VFM模式的PWM/VFM自動切換模式，和為了減輕噪聲在輕負載時仍然以固定頻率控制開關的強制固定在PWM模式的方式。
內建的保護電路包括了，在每個周期內限制流過LX電流的電流限流電路和負載電流過了限流電流或輸出端短路的狀態持續時間后關斷鎖定內部驅動管的鎖定保護電路。若要釋放鎖定保護狀態，把CE使能信號重置，或重置電源電壓（電源電壓低于欠壓鎖定檢測電壓）。電路還內建了過熱關斷保護電路，如果芯片內部的溫度過了值，系統將會重置。
※）輸出電流依賴于工作條件及外部器件，因此這是一個供參考的近似值。
■ 特點
● 消費電流·······················································典型值 40μA(在VFM模式下，無負載)
● 待機電流·······················································值 5μA
● 輸入電壓范圍················································2.3V~5.5V(額定值：6.5V)
● 輸出電壓范圍(A,B版本)·································0.6V~3.3V (0.1V步進，※0.8V以下的情況，使用條件有限制)
(C版本)····································0.8V～3.3V
● 輸出電壓(A,B版本)·································&plun;1.5%(VOUT≧1.2V)，&plun;18mV(VOUT＜1.2V)
● 反饋電壓(C版本)····································&plun;9mV(VFB=0.6V)
● 輸出電壓/反饋電壓溫度漂移系數··················&plun;100ppm/°C
● 開關頻率·······················································典型值 2.25MHz
● 開關占空比·············································小值 100%
● 內置驅動器導通電阻·····································典型值 P型驅動管 0.23Ω，N型驅動管0.20Ω(VIN=3.6V時)
● 欠壓鎖定檢測電壓·········································典型值 2.0V
● 軟起動時間····················································典型值 0.15ms
● 內建電感限流電流·········································典型值 1.7A
● 內建鎖定保護電路·········································典型值 1.5ms
● 封裝·······························································DFN(PLP)2020−8
■ 應用范圍
● 使用電池供電的設備
● 照相機，攝像機，便攜通訊設備
● WLAN
