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Product Spec Banner
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RT9721A/RT9721B 是一系列低電壓單 N-MOSFET 高側電源開關（High-Side Power Switch），專為自供電（Self-Powered）及匯流排供電（Bus-Powered）的 USB（Universal Serial Bus）應用最佳化設計。RT9721A/RT9721B 內建電荷幫浦（Charge Pump）驅動電路，用於驅動內部 MOSFET 開關；其低導通電阻（RDS(ON)）僅 80mΩ，可滿足 USB 規範對電壓降的要求。此外，產品提供故障旗標（Flag）輸出，可向本地 USB 控制器回報異常狀態。 本產品還具備多項保護功能，包括軟啟動（Soft-Start）功能，可限制插入設備時的湧入電流；過溫保護（Thermal Shutdown）功能，可避免高電流負載造成開關元件損壞；以及欠壓鎖定保護（UVLO），確保只有在有效輸入電壓存在時元件才會啟動。 依據 USB 電源規範要求，雙埠應用時最大輸出電流限制通常為 750mA。此外，其靜態電流低至 50μA，使其非常適合可攜式電池供電設備。 RT9721A 不具備輸出自動放電（Auto-Discharge）功能，而 RT9721B 則內建輸出自動放電功能，可在關閉時快速釋放輸出端殘留電荷。 RT9721A/RT9721B 採用 SOT-23-5 封裝，可有效節省電路板空間並降低系統尺寸。
RT9721A/RT9721B 電路圖
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<div class="spec-list"><ul class="lv1"><li>Compliant to USB Specifications </li><li>Built-In N-MOSFET <ul class="lv2"> <li></li><li>Typical R<sub>DS(ON)</sub> : 80mΩ </li></ul> </li><li>Output Can Be Forced to Higher Than Input (Off-State) </li><li>Low Supply Current : <ul class="lv2"> <li></li><li>50μA Typical at Switch On State </li><li>0.1μA Typical at Switch Off State </li></ul> </li><li>Guaranteed 500mA Continuous Load Current </li><li>Wide Input Voltage Ranges : 2.5V to 5.5V </li><li>Open-Drain Fault Flag Output </li><li>Hot Plug-In Application (Soft-Start) </li><li>2.15V Typical Under-Voltage Lockout (UVLO) </li><li>Current Limiting Protection </li><li>Thermal Shutdown Protection </li><li>Reverse Current Flow Blocking (no body diode) </li><li>UL Approved-E219878 <img width="42" height="38" alt="" align="middle" style="width: 31px; height: 23px; vertical-align: middle;" src="/assets/2011/08/03/99769apajs.GIF"> </li><li>RoHS Compliant and Halogen Free </li></ul></div>
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RT9721A/RT9721B 訂購資訊
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<div class="spec-list"><ul class="lv1"><li>USB Bus/Self Powered Hubs </li><li>USB Peripherals </li><li>Notebook, Motherboard PCs </li></ul></div>
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