Intel PXA27X manual Power Management Integrated Circuit Requirements, Nbattfault

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Intel® PXA27x Processor Family Power Requirements

System designers can include a software-controlled threshold level detection for nVDD_FAULT to allow an optional SDRAM keep-alive capability.

7.2nBATT_FAULT

nBATT_FAULT indicates that the main battery is low or has been removed from the device, giving the PXA27x processor an indication that power will shortly cease. Until that time, the processor can operate for a limited period from a lithium/lithium manganese coin-cell backup battery, or from a super cap that can only supply the processor for a few cycles of full-run power.

In the event of nBATT_FAULT assertion, the PXA27x processor enters an emergency form of sleep, where the only handshaking is with external SDRAM memory (putting it into self-refresh mode) to ensure that memory contents are preserved if possible (obviously, the refresh current can eventually deplete the super cap or backup battery, but not as quickly as the PXA27x processor in run mode). Supporting these features must be understood at both the board-level design and by the PMIC.

Note: The PXA27x processor does not recognize a wakeup event while nBATT_FAULT is asserted.

If the system is powered from an AC main source (90 VAC to 240 VAC or equivalent) while nBATT_FAULT is asserted, that fact may be used to gate off nBATT_FAULT and its normal effects on the system. Recognition of this condition can be built into the PMIC, and a signal indicating an AC power source is active is provided from the PMIC to the PXA27x processor GPIO<0> or GPIO<1> signals.

8.0Power Management Integrated Circuit Requirements

This section provides guidelines for designing a power management integrated circuit (PMIC) for the PXA27x processor.

8.1General PMIC Characteristics

Table 9 shows the overall characteristics for a PXA27x processor PMIC.

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Contents Intel PXA27x Processor Family Power Requirements Application NoteApplication Note Contents Figures Introduction Naming ConventionsPower Domain Enable1 Units Specified Levels Tolerance Volts Intel PXA27x Processor Power Supply DomainsExternal Power Supply Descriptions PLL PxtalSram DMAPower Domains and System Voltage/Current Requirements Intel PXA27x Processor Power SuppliesIntel PXA27x Processor Voltage Domains Sheet 1 Voltage DescriptionPower Supply Configuration in a Minimal System Intel PXA27x Processor Voltage Domains Sheet 2Modeling Intel PXA27x processor power consumption Regulators Required to Power the Intel PXA27x ProcessorIntel PXA27x Processor Vcccore Supply Current Regulator DescriptionIntel PXA27x Processor Vcccore Supply Current Supply Current For Each Power DomainFrequency Dhrystones Power MPEG4 Decode Power Stress Default Reset Values Intel PXA27x Processor Supply Current For Each Power DomainName Functional Units Current mA @ Power VccbattBatteries Main BatteryBackup Battery Backup Battery Description Battery Chargers and Main PowerPossible Backup Battery Configurations Typical Battery and External Regulator Configuration Intel PXA27x Processor Low Power Operating Modes Intel PXA27x Processor Operating ModesCPDIS=0 Power Controller Interface SignalsCPDIS=1 Power Enable Pwren System Power Enable Sysen / GPIO2Power Manager I2C Clock Pwrscl / GPIO3 Power Controller Interface SignalsPower Manager I2C Data Pwrsda / GPIO4 On, Off, and ResetUser-Initiated Hard Reset Input System-Level Considerations for I2CUniversal Subscriber Identity Module Usim Power Manager Capacitor SignalsNRESET Output from Pmic to the Intel PXA27x Processor Cold-Start Power-On and Hardware Reset Power Mode SequencingPower-On Initial Power Up and Deep Sleep Exit Sequence Vcccore Vccpll VccsramHardware Reset Behavior Intel PXA27x Processor Family Power Requirements Sysdel PwrdelSleep and Deep Sleep Sleep Entry and ExitDeep Sleep Entry and Exit Dynamic Voltage Management DVM Vcccore Regulator and Dynamic Voltage ManagementIntel PXA27x Processor Voltage Manager Fault Management Power Manager I2C InterfaceNVDDFAULT DVM SequencingGeneral Pmic Characteristics Power Management Integrated Circuit RequirementsNBATTFAULT Characteristic Description Features of a PmicGeneral Pmic Characteristics Programmable Voltage Control DVM Control RegisterDVM Control and Status Register Other Aspects of an Integrated Power ControllerSummary Intel PXA27x Processor Family Power Requirements
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