IBM EM78P447N manual Residue-Voltage Protection, Reset

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EM78P447N

8-Bit Microcontroller with OTP ROM

4.11 Residue-Voltage Protection

When battery is replaced, device power (Vdd) is taken off but residue-voltage remains. The residue-voltage may trips below Vdd minimum, but not to zero. This condition may cause a poor power on reset. Fig.16 and Fig.17 show how to build the residue-voltage protection circuit.

Vdd

EM78P447N

/RESET

Vdd

33K

Q1

10K

40K1N4684

Fig. 14 The Residue Voltage Protection Circuit 1

Vdd

EM78P447N

/RESET

Vdd

R1

Q1

40KR2

Fig. 15 The Residue Voltage Protection Circuit 2

Product Specification (V1.1) 03.30.2005

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(This specification is subject to change without further notice)

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Contents EM78P447N Elan Microelectronics Corporation Contents Specification Revision History General Description EM78P447NBWM PIN Assignment Symbol Pin No Type Function EM78P447NAP and EM78P447NAM Pin DescriptionEM78P447NAS Pin Description Power supply EM78P447NBP and EM78P447NBWM Pin DescriptionEM78P447NCK and EN78P447NCM Pin Description EM78P447NDK and EM78P447NDM Pin Description Function Description1 R0 Indirect Addressing Register Operational Registers2 R1 Time Clock /Counter 3 R2 Program Counter & StackFffh Call RET Retl RetiData Memory Configuration 6 R5~R7 Port 5 ~ Port7 5 R4 RAM Select Register7 R8~R1F and R20~R3E General Purpose Register R5, R6 and R7 are I/O registers8 R3F Interrupt Status Register Special Purpose RegistersAccumulator Control RegisterIocb Wake-up Control Register for Port6 3 IOC5 ~ IOC7 I/O Port Control RegisterTCC Rate WDT RateWUE Ioce WDT Control RegisterExie Iocf Interrupt Mask RegisterTCC/WDT & Prescaler TCC and WDT Block DiagramIOD I/O PortsReset Reset and Wake-upSLEEP2 SLEEP1 Usage of Sleep1 and Sleep2 ModeSummary of the Initialized Values for Registers Address Name Reset Type BitExif Tcif R3FISRWUE7 WUE6 WUE5 WUE4 IocbPrevious value before reset Previous status before resetStatus of RST, T, and P of Status Register Events that may Affect the T and P StatusInterrupt Controller Reset Block DiagramOscillator Oscillator ModesMode Summary of Maximum Operating Speeds Crystal Oscillator/Ceramic ResonatorsXTALConditions Fxt max.MHzOscillator Type Frequency Mode C1pF C2pF External RC Oscillator ModeHXT LXTCode Option Register Word Code Option RegisterProtect PR2~PR0 are protect bits, protect type as followingExternal Power On Reset Circuit Power On ConsiderationsCustomer ID Register Word Bit 12~0 Customer’s ID codeResidue-Voltage Protection ResetInstruction Set DAA NOPContw SlepDJZ R Djza RRrca R RRC RAC Test Input/Output W aveform Timing DiagramSymbol Parameter Condition Min Typ Max Unit DC Electrical CharacteristicTa= 25 C, VDD= 5.0V±5%, VSS= Items RatingAC Electrical Characteristic Symbol Parameter Conditions Min Typ Max UnitTa=- -40 C ~ 85 C, VDD=5V ±5%, VSS=0V Vih, Vil of TCC, /INT, /RESET Pin Device characteristicPort5, Port6 Port7 Voh vs. Ioh,VDD=5V Port5, Port6, and Port7 Voh vs. Ioh, VDD=3V Vol/Iol VDD=5V Vol/Iol VDD=3V Vol/Iol 100 Vol/Iol WDT Cext=100pF, Typical RC OSC Frequency Typical ICC1 and ICC2 vs. Temperature Maximum ICC1 and ICC2 vs. Temperature Typical ISB1 and ISB2 vs. Temperature Maximum ISB1 and ISB2 vs. Temperature EM78P447N HXT ImA Package Type Pin Count Package Size Lead plastic dual inline package（DIP）－ 300 milLead plastic dual inline package（DIP）－ 600 mil Lead plastic dual inline skinny package（DIP）－ 300 mil838 27TYP EM78P447N