双1.4MHz的同步降压稳压器，支持USB Dying Gasp应用

摘要：一个安全的USB“垂死的喘息”关机需要一个本地的储能电容，电源设备，并延长运作有序关闭。一个5VUSB“垂死的喘息”应用程序中的电路提供电源失效输出一个2.88ms的预警时间。特色的MAX1970/MAX1972降压与PFO的监管。

Maxim>AppNotes>BatteryManagementPower-SupplyCircuitsKeywords:dyinggasp,USB,power-failwarning,power-failoutput,PFO,PFOthreshold,DC-DCconverter,DC-DCconverterefficiency,Dec18,2001energystoragecapacitor,step-downregulatorAPPLICATIONNOTE891Dual1.4MHzSynchronousBuckRegulatorSupportsUSBDyingGaspApplicationsAbstract:AsafeUSB"dyinggasp"shutdownrequiresalocalenergystoragecapacitortopowerthedeviceandprolongoperationfororderlyshutdown.Acircuitfora5VUSB"dyinggasp"applicationprovidesapower-failoutputwarningtimeof2.88ms.TheMAX1970/MAX1972step-downregulatorswithPFOarefeatured.Manyportableuniversalserialbus(USB)devicesarepoweredfromtheUSBport.Mostofthesedevicesneedapowerfailwarningto