DS12885 Maxim Integrated Products, DS12885 Datasheet
DS12885
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DS12885 Summary of contents
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... If a primary power failure is detected, the device CC automatically switches to a backup supply. A lithium coin-cell battery can be connected to the V pin on the DS12885 to maintain time and date operation when primary power is absent. The device is accessed through a multiplexed byte-wide interface, which sup- ports both Intel and Motorola modes. ...
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Real-Time Clocks ABSOLUTE MAXIMUM RATINGS Voltage Range on V Pin Relative to Ground .....-0.3V to +6.0V CC Operating Temperature Range ................................................... Commercial (noncondensing) .............................0°C to +70°C Operating Temperature Range ................................................... Industrial (noncondensing)...............................-40°C to +85°C Storage Temperature Range EDIP ..................................................................-40°C to ...
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DC ELECTRICAL CHARACTERISTICS ( 3.0V over the operating range, unless otherwise noted.) (Note 2) CC BAT A PARAMETER SYMBOL V Current (OSC On); BAT T = +25° 3.0V A BACKUP V Current ...
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Real-Time Clocks AS t ASD AD0–AD7 WRITE AD0–AD7 READ AS t ASD DS t ASD R ASL AD0–AD7 WRITE 4 _____________________________________________________________________ Motorola Bus Read/Write Timing PW ASH t ASED t CYC ...
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AS t ASD DS t ASD R/W CS AD0–AD7 IRQ Release Delay Timing DS RESET IRQ t IRDS PF(MAX) V PF(MIN) RECOGNIZED INPUTS VALID OUTPUTS t CYC PW ASH t ASED ...
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Real-Time Clocks POWER-UP/POWER-DOWN CHARACTERISTICS (T = -40°C to +85°C) (Note 2) A PARAMETER SYMBOL Recovery at Power-Up V Fall Time PF(MAX) V PF(MIN) V Rise Time PF(MIN) V PF(MAX) DATA RETENTION (T = +25°C) ...
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... AD0–AD7 RLCR Typical Operating Characteristics 32768.70 32768.60 +25°C 32768.50 32768.40 32768.30 32768.20 32768.10 32768.00 3.8 4.0 DIVIDE DIVIDE 16:1 MUX DS12885 CLOCK/CALENDAR UPDATE LOGIC _____________________________________________________________________ Real-Time Clocks OSCILLATOR FREQUENCY vs 4.5 4.8 5.0 5.5 5.3 V (V) CC Functional Diagram DIVIDE BY 64 SQUARE- ...
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Real-Time Clocks PIN SO, EDIP PLCC TQFP PDIP — — 5–10, 4–11 4– 15, 20 12, 17 ...
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PIN SO, NAME EDIP PLCC TQFP PDIP 11, 15, 20, 22 16, 20, 13, 18, 23, 25 RESET Connection. This ...
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... The IRQ pin is an open-drain output and requires an external pullup resistor to V Connection for a Primary Battery. (DS12885 Only.) Battery voltage must be held between the minimum and maximum limits for proper operation backup supply is not supplied, V must be grounded ...
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... Detailed Description The DS12885 family of RTCs provide 14 bytes of real- time clock/calendar, alarm, and control/status registers and 114 bytes (113 bytes for DS12C887 and DS12C887A) of nonvolatile, battery-backed static RAM. A time-of-day alarm, three maskable interrupts with a common interrupt output, and a programmable square- wave output are available. The devices also operate in either 24-hour or 12-hour format with an AM/PM indica- tor ...
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Real-Time Clocks Clock Accuracy The accuracy of the clock is dependent upon the accu- racy of the crystal and the accuracy of the match between the capacitive load of the oscillator circuit and the capacitive load for which the crystal ...
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... Read/Write Bit. * DS12C887, DS12C887A only. General-purpose RAM on DS12885, DS12887, and DS12887A. Note: Unless otherwise specified, the state of the registers is not defined when power is first applied. Except for the seconds regis- ter, 0 bits in the time and date registers can be written to 1, but may be modified when the clock updates. 0 bits should always be written to 0 except for alarm mask bits ...
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... Read/Write Bit. * DS12C887, DS12C887A only. General-purpose RAM on DS12885, DS12887, and DS12887A. Note: Unless otherwise specified, the state of the registers is not defined when power is first applied. Except for the seconds regis- ter, 0 bits in the time and date registers can be written to 1, but may be modified when the clock updates. 0 bits should always be written to 0 except for alarm mask bits ...
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Control Registers The real-time clocks have four control registers that are accessible at all times, even during the update cycle. MSB BIT 7 BIT 6 BIT 5 UIP DV2 Bit 7: Update-In-Progress (UIP). This bit is a status flag that ...
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Real-Time Clocks MSB BIT 7 BIT 6 BIT 5 SET PIE Bit 7: SET. When the SET bit is 0, the update transfer functions normally by advancing the counts once per second. When the SET bit is written to 1, ...
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MSB BIT 7 BIT 6 BIT 5 IRQF PF Bit 7: Interrupt Request Flag (IRQF). This bit is set to 1 when any of the following are true PIE = AIE = ...
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Real-Time Clocks Century Register (DS12C887/DS12C887A Only) The century register at location 32h is a BCD register designed to automatically load the BCD value 20 as the year register changes from 99 to 00. The MSB of this register is not ...
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Table 3. Periodic Interrupt Rate and Square-Wave Output Frequency SELECT BITS t PERIODIC PI REGISTER A INTERRUPT RATE RS3 RS2 RS1 RS0 None 3.90625ms 7.8125ms ...
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... THAT WILL GIVE A CONTINUITY PATH BETWEEN THE RAM CLEAR PIN AND GROUND. 20 ____________________________________________________________________ SQW 22 N.C. 21 RCLR 20 V BAT 19 IRQ 18 RESET GND 15 R N.C. SQW N.C. 1 DS12885Q 2 MOT PLCC Pin Configurations MOT N. SQW N. N.C. N.C. AD0 4 21 (RCLR) AD1 5 20 N.C. DS12887 AD2 6 19 IRQ DS12887A AD3 ...
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... DS 24 PDIP 17 GND 24 EDIP 28 PLCC TQFP PROCESS: CMOS SUBSTRATE CONNECTED TO GROUND ____________________________________________________________________ Real-Time Clocks Ordering Information TOP MARK* DS12885 DS12885 DS12885Q DS12885Q DS12885Q DS12885Q DS12885S DS12885S DS12885S DS12885 DS12885 DS12887 DS12887A DS12C887 DS12C887AA Thermal Information THETA-JA (°C/W) THETA-JC (°C/ 105 22 95 ...
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... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 22 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2010 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc ...