Philips P89LPC907, P89LPC906, P89LPC908 user manual Brownout Detection

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Philips Semiconductors

User’s Manual - Preliminary -

 

 

 

POWER MONITORING FUNCTIONS

P89LPC906/907/908

7. POWER MONITORING FUNCTIONS

 

 

The P89LPC906/907/908 incorporates power monitoring functions designed to prevent incorrect operation during initial power- on and power loss or reduction during operation. This is accomplished with two hardware functions: Power-on Detect and Brownout Detect.

BROWNOUT DETECTION

The Brownout Detect function determines if the power supply voltage drops below a certain level. The default operation for a Brownout Detection is to cause a processor reset. However, it may alternatively be configured to generate an interrupt by setting the BOI (PCON.4) bit and the EBO (IEN0.5) bit.

Enabling and disabling of Brownout Detection is done via the BOPD (PCON.5) bit, bit field PMOD1-0 (PCON.1-0) and user configuration bit BOE (UCFG1.5). If BOE is in an unprogrammed state, brownout is disabled regardless of PMOD1-0 and BOPD. If BOE is in a programmed state, PMOD1-0 and BOPD will be used to determine whether Brownout Detect will be disabled or enabled. PMOD1-0 is used to select the power reduction mode. If PMOD1-0 = ’11’, the circuitry for the Brownout Detection is disabled for lowest power consumption. BOPD defaults to ’0’, indicating brownout detection is enabled on power-on if BOE is programmed.

If Brownout Detection is enabled, the operating voltage range for VDD is 2.7V-3.6V, and the brownout condition occurs when VDD falls below the Brownout trip voltage, VBO (see D.C. Electrical Characteristics), and is negated when VDD rises above VBO. If Brownout Detection is disabled, the operating voltage range for VDD is 2.4V-3.6V. If the P89LPC906/907/908 device is to operate with a power supply that can be below 2.7V, BOE should be left in the unprogrammed state so that the device can operate at 2.4V, otherwise continuous brownout reset may prevent the device from operating.

If Brownout Detect is enabled (BOE programmed, PMOD1-0 ≠ ’11’, BOPD = 0), BOF (RSTSRC.5) will be set when a brownout is detected, regardless of whether a reset or an interrupt is enabled, . BOF will stay set until it is cleared in software by writing ’0’ to the bit. Note that if BOE is unprogrammed, BOF is meaningless. If BOE is programmed, and a initial power-on occurs, BOF will be set in addition to the power-on flag (POF - RSTSRC.4).

For correct activation of Brownout Detect, certain VDD rise and fall times must be observed. Please see the datasheet for specifications.

2003 Dec 8

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Contents User Manual Table of Contents Power-On reset code execution Brownout Detection Power-On Detection Power Reduction Modes103 List of Figures List of Figures P89LPC906 PIN ConfigurationsProduct Comparison Logic SymbolsKB Code Flash Block Diagram P89LPC906CPU Oscillator DividerUart Block Diagram P89LPC907Byte Data RAM ClockData RAM Port Block Diagram P89LPC908PIN Descriptions P89LPC906 P1.0 PIN Descriptions P89LPC907TxD P1.2Keyboard Input P1.0 P1.5 PIN Descriptions P89LPC908P1.1 RxDSpecial function registers table P89LPC906 Special function registersMSB LSB Hex Special function registers table P89LPC907 CMP1 Cmpref TRIM.5 TRIM.4 TRIM.3 TRIM.2 TRIM.1 TRIM.0 WDCON# Special function registers table P89LPC908 KB2 KB6 KB5 KB4 TL0 Data Memory OrganizationSFR CodeClock Definitions Enhanced CPUCPU Clock Oscclk LOW Speed Oscillator Option P89LPC906Clock Output P89LPC906 Oscillator Option SELECTION- P89LPC906ON-CHIP RC Oscillator Option Watchdog Oscillator OptionBIT Symbol Function CPU Clock Cclk Wakeup DelayExternal Clock Input Option P89LPC906 CPU Clock Cclk Modification Divm RegisterHigh freq LOW Power Select P89LPC906Med freq Low freqCPU Clocks Interrupt Priority Structure Flag Bits Address Enable Bits Priority RankingSummary of Interrupts P89LPC906 Description Interrupt ArbitrationExternal Interrupt PIN Glitch Suppression External Interrupt InputsSummary of Interrupts P89LPC907,P89LPC908 Description TI & RIBopd EBO Rtcf Kbif Interrupts QUASI-BIDIRECTIONAL Output Configuration Port ConfigurationsNumber of I/O Pins Available Clock Source Reset Option RSTPort latch data Open Drain Output ConfigurationPUSH-PULL Output Configuration INPUT-ONLY ConfigurationPort 0 Analog Functions Strong Port latch data Port pin Input data Glitch rejectionPort Output Configuration P89LPC908 Port Output Configuration P89LPC906Port Output Configuration P89LPC907 Ports Ports TMOD.7 TmodTMOD.6 TMOD.3Mode Overflows. ModeTamod P89LPC907 TAMOD.7-1Tcon T0C/T = Overflow TLn THn TFn Interrupt T0 Pin PclkT0C/T = Overflow THn TFnTR0 ENT0 Pclk TH0 Timer Overflow Toggle Output P89LPC907Pclk TL0 Timers 0 REAL-TIME Clock Source UCFG1.2 UCFG1.1 UCFG1.0 Cclk Frequency RTC Clock Frequency FOSC2 FOSC1 FOSC0 RTCS10Xclk Divm CclkWDT Oscillator/DIVM RC Oscillator/DIVMUndefined External clock/DIVMREAL-TIME Clock INTERRUPT/WAKE UP Reset Sources Affecting the REAL-TIME ClockChanging RTCS1-0 Rtccon REAL-TIME CLOCK/SYSTEM Timer Brownout Detection Brownout Options POWER-ON DetectionPower Reduction Modes Power Reduction Modes Pcon Pcona Power Monitoring Functions Modes UartBaud Rate Generator and Selection SFR SpaceUpdating the BRGR1 and BRGR0 Sfrs SFR Locations for UARTsBrgcon Framing ErrorBreak Detect Scon Sstat More about Uart ModeSerial Port Mode 0 Double Buffering Must Be Disabled FE and RI when SM2 = 1 in Modes 2 Framing Error and RI in Modes 2 and 3 with SM2 =More about Uart Modes 2 PCON.6 RB8 SMOD0Double Buffering in Different Modes Double BufferingTransmission with and without Double Buffering 9TH BIT BIT 8 in Double Buffering Modes 1, 2Automatic Address Recognition Multiprocessor CommunicationsUart Uart Block Diagram of Reset POWER-ON Reset Code ExecutionRstsrc Comparator Configuration Internal Reference Voltage Comparator and Power Reduction ModesComparator Interrupt CIN1A CO1 CMP1 CmprefComparator Configuration Example Analog Comparators Kbcon KbpatnKbmask Wdte Wdse Function Watchdog timer configurationWatchdog Function Feed Sequence Wdcon PRE2-PRE0 P89LPC906/907/908 Watchdog Timeout ValuesPrescaler Reset Pclk Watchdog Timer in Timer ModeWatchdog Control registerWatchdog Clock Source Power Down OperationPrescaler CLKWatchdog Timer Watchdog Timer AUXR1 Software ResetDual Data Pointers Move code byte relative to Dptr to the accumulator MOVCA, @A+DPTRMOVXA, @DPTR MOVX@DPTR, aUsing Flash AS Data Storage FeaturesGeneral Description Introduction to IAP-LITEFlash Program Memory Fmcon Assembly language routine to erase/program all or part of a Accessing Additional Flash ElementsUCFG1 ERASE-PROGRAMMING Additional Flash ElementsReading Additional Flash Elements Fmadrl Conf P89LPC906 User Configuration BytesUCFG1 SECx User Security BytesAddress xxxxh Unprogrammed value 00hBootstat BootvecLogical ArithmeticData Transfer Mnemonic Description Bytes Cycles Hex CodeBranching BooleanB8-BF RetiD8-DF Miscellaneous2003 Dec Initial release 104 Index Dual Data Pointers Port 0 12, 13 SFR 109 P89LPC906/907/908
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