DP8572AN National Semiconductor, DP8572AN Datasheet
DP8572AN
Specifications of DP8572AN
DP8572
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DP8572AN Summary of contents
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... This logic is used by the RTC to issue a power fail interrupt and lock out the p interface The time power fails may be logged into RAM automatically when V Block Diagram TRI-STATE is a registered trademark of National Semiconductor Corporation C 1995 National Semiconductor Corporation TL F 9980 V ...
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Absolute Maximum Ratings Specifications for the 883 version of this product are listed separately Supply Voltage ( Input Voltage ( Output Voltage ( ...
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AC Electrical Characteristics PFAIL Symbol READ TIMING t Address Valid Prior to Read Strobe AR t Read Strobe Width (Note Chip Select to Data ...
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... Absolute Maximum Ratings The 883 specifications are written to reflect the current (at the time of printing) Rel Electrical Test Specifica- tions (RETS) established by National Semiconductor for this product For a copy of the latest version of the RETS please contact your local National Semiconduc- tor sales office or distributor ...
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Military Version AC Electrical Characteristics and PFAIL Symbol READ TIMING t Address Valid Prior to Read Strobe AR t Read Strobe Width (Note ...
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Timing Waveforms Read Timing Diagram Write Timing Diagram 9980 – 9980 – 4 ...
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... This is the main system power pin CC GND This is the common ground power pin for both V and V CC Connection Diagrams Dual-In-Line P control Order Number DP8572AN or DP8572AMD 883 See NS Package Number D24C or N24C Plastic Chip Carrier The BB Top View Order Number DP8572AV See NS Package Number V28A ...
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Functional Description The DP8572A contains a fast access real time clock inter- rupt control logic power fail detect logic and CMOS RAM All functions of the RTC are controlled by a set of seven registers A simplified block diagram that ...
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Functional Description (Continued) INITIAL POWER-ON of BOTH V and and V may be applied in any sequence In order for BB CC the power fail circuitry to function correctly whenever power is off the V pin ...
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Functional Description (Continued) The oscillator is programmed via the Real Time Mode Reg- ister to operate at various frequencies The crystal oscillator is designed to offer optimum performance at each frequen- cy Thus at 32 768 kHz the oscillator is ...
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Functional Description (Continued) Interrupts Fall Into Three Categories 1 The Alarm Compare Interrupt Issued when the value in the time compared RAM equals the counter 2 The Periodic Interrupts These are issued at every incre- ment of the specific clock ...
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Functional Description (Continued) 12 ...
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Functional Description (Continued) FIGURE 6 System-Battery Switchover (Upper Left) Power Fail If chip select is low when a power failure is detected a safety circuit will ensure that if a read or write is held active continuously for greater than ...
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Functional Description (Continued) the chip is unlocked but only after another 30 s min 63 s max debounce time The system designer must en- sure that his system is stable when power has returned The power fail circuitry contains active ...
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Functional Description (Continued) MAIN STATUS REGISTER The Main Status Register is always located at address 0 regardless of the register block or the page selected D0 This read only bit is a general interrupt status bit that is taken directly ...
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Functional Description (Continued) D5 The Delay Enable bit is used when a power fail occurs If this bit is set a 480 s delay is generated internally before the P interface is locked out This will enable the access the ...
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Functional Description (Continued) D7 This bit is used to program the signal appearing at the MFO output as follows D7 MFO Output Signal 0 Power Fail Interrupt 1 Buffered Crystal Oscillator INTERRUPT CONTROL REGISTER 0 D0 –D5 These bits are ...
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Control and Status Register Address Bit Map Main Status Register ADDRESS Page Register RAM Select Select Periodic Flag Register ...
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Application Hints Suggested Initialization Procedure for DP8572A in Battery Backed Applications that use the V Pin BB 1 Enter the test mode by writing bit D7 in the Period- ic Flag Register 2 Write zero to the ...
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Typical Performance Characteristics Operating Current vs Supply Voltage (Single Supply Mode F 32 768 kHz) e OSC Standby Current vs Power Supply Voltage (F 32 768 kHz) e OSC Operating Current vs Supply Voltage (Battery Backed Mode F 32 768 ...
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... Physical Dimensions inches (millimeters) 24-Lead Hermetically Sealed Dual-In-Line Package (D) Order Number DP8572AMD 883 NS Package Number D24C Molded Dual-In-Line Package (N) Order Number DP8572AN NS Package Number N24C 21 ...
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