bq3287/bq3287A Real-Time Clock (RTC) Module Features ➤ Direct clock/calendar replacement for IBM ® AT-compatible computers and other applications ➤ Functionally compatible with the DS1287/DS1287A and MC146818A ➤ 114 bytes of general nonvolatile storage ➤ Calendar in day of the week, day of the month, months, and years with automatic leap-year adjustment ➤ Programmable square wave output ➤ Three individually maskable interrupt event flags: ➤ Integral lithium cell and crystal ➤ 160 ns cycle time allows fast bus operation ➤ Selectable Intel or Motorola bus timing - Periodic rates from 122 µs to 500 ms - Time-of-day alarm once per second to once per day - End-of-clock update cycle ➤ 14 bytes for clock/calendar and control ➤ Better than one minute per month clock accuracy ➤ BCD or binary format for clock and calendar data General Description ➤ Time of day in seconds, minutes, and hours - 12- or 24-hour format - Optional daylight saving adjustment Pin Connections MOT NC NC AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7 VSS 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13 The CMOS bq3287/bq3287A is a low-power microprocessor peripheral providing a time-of-day clock and 100-year calendar with alarm features and battery operation. O t he r f e a tu re s i n cl u d e th re e maskable interrupt sources, squarewave output, and 114 bytes of gene r al n o n volatile storage. The bq3287A version is identical to the bq3287, with the addition of the RAM clear input. The bq3287 is a fully compatible r e a l - t i m e c l o c k f o r I B M ATcompatible computers and other app l i c a t i o n s. T h e b q 3 2 8 7 w r i t e protects the clock, calendar, and storage registers during power failure. The integral backup energy source then maintains data and operates the clock and calendar. As shipped from Benchmarq, the real time clock is turned off to maximize battery capacity for in-system operation. The bq3287 is functionally equivalent to the bq3285, except that the battery (16, 20) and crystal (2, 3) pins are not accessible. These pins are connected internally to a coin cell and quartz crystal. The coin cell is sized to provide 10 years of data retention and clock operation in the absence of power. For a complete description of features, operating conditions, electrical characteristics, bus timing, and pin descriptions, see the bq3285 data sheet. Pin Names VCC SQW NC NC/RCL NC INT RST DS NC R/W AS CS AD0–AD7 Multiplexed address/data input/output MOT Bus type select input CS Chip select input AS Address strobe input DS Data strobe input R/W Read/write input INT Interrupt request output 24-Pin DIP Module PN328701.eps Sept. 1996 D 1 RST Reset input SQW Square wave output NC No connect RCL RAM clear input (bq3287A only) VCC +5V supply VSS Ground bq3287/bq3287A Absolute Maximum Ratings Value Unit VCC Symbol DC voltage applied on VCC relative to VSS Parameter -0.3 to 7.0 V VT DC voltage applied on any pin excluding VCC relative to VSS -0.3 to 7.0 V VT ≤ VCC + 0.3 TOPR Operating temperature 0 to +70 °C Commercial -20 to +70 °C Extended “I” -40 to +70 °C Commercial -40 to +70 °C Extended “I” -10 to +70 °C Commercial -20 to +70 °C Extended “I” 260 °C For 10 seconds Storage temperature TSTG Temperature under bias TBIAS Soldering temperature TSOLDER Note: Conditions Permanent device damage may occur if Absolute Maximum Ratings are exceeded. Functional operation should be limited to the Recommended DC Operating Conditions detailed in this data sheet. Exposure to conditions beyond the operational limits for extended periods of time may affect device reliability. Recommended DC Operating Conditions (TA = TOPR) Symbol Parameter Minimum Typical Maximum Unit 4.5 5.0 5.5 V 0 0 0 V -0.3 - 0.8 V - VCC + 0.3 V VCC Supply voltage VSS Supply voltage VIL Input low voltage VIH Input high voltage 2.2 Note: Typical values indicate operation at TA = 25°C. DC Electrical Characteristics (TA = TOPR, VCC = 5V ± 10%) Symbol Parameter Minimum Typical Maximum Unit Conditions/Notes ILI Input leakage current - - ±1 µA VIN = VSS to VCC ILO Output leakage current - - ±1 µA AD0–AD7, INT and SQW in high impedance VOH Output high voltage 2.4 - - V IOH = -1.0 mA VOL Output low voltage - - 0.4 V IOL = 4.0 mA ICC Operating supply current - 7 15 mA VSO Supply switch-over voltage - 3.0 - V VPFD Power-fail-detect voltage 4.0 4.17 4.35 V IRCL Input current when RCL = VSS - - 185 µA Internal 30K pull-up (bq3287A only) IMOTH Input current when MOT = VCC - - -185 µA Internal 30K pull-down Note: Min. cycle, duty = 100%, IOH = 0mA, IOL = 0mA Typical values indicate operation at TA = 25°C, VCC = 5V. Sept. 1996 D 2 bq3287/bq3287A Power-Down/Power-Up Timing Symbol (TA = TOPR) Parameter Minimum Typical Maximum Unit tF VCC slew from 4.5V to 0V 300 - - µs tR VCC slew from 0V to 4.5V 100 - - µs tCSR CS at VIH after power-up 20 - 200 ms tDR Data-retention and timekeeping time 10 - - years Note: Conditions Internal write-protection period after VCC passes VPFD on power-up. TA = 25°C. Clock accuracy is better than ± 1 minute per month at 25°C for the period of tDR. Caution: Negative undershoots below the absolute maximum rating of -0.3V in battery-backup mode may affect data integrity. Power-Down/Power-Up Timing Sept. 1996 D 3 bq3287/bq3287A 24-Pin MT (T-type module) 24-Pin MT (T-type module) Dimension A A1 B C D E e G L S Minimum 0.360 0.015 0.015 0.008 1.320 0.685 0.590 0.090 0.120 0.100 Maximum 0.375 0.022 0.013 1.335 0.700 0.620 0.110 0.130 0.120 All dimensions are in inches. Sept. 1996 D 4 bq3287/bq3287A Data Sheet Revision History Change No. Page No. 1 1 Address strobe input Clarification 1 2 Power-fail detect voltage VPFD Was 4.1 min, 4.25 max; is 4.0 min, 4.35 max 2 1 Was : “As shipped from Benchmarq, the backup cell is electrically isolated from the memory. ” Is: “As shipped from Benchmarq, the backup cell is electrically isolated from the active circuitry. ” Clarification 2 2, 4 Changed temperature from N (industrial, -40 to +85°C) to I (extended, -20 to +70°C) Specification change 3 2 Notes: Description Nature of Change IRCL max. was 275; is now 185. Pull-up = 30K IMOTH max. was -275; is now -185. Pull-down = 30K Changed values Change 1 = Nov. 1992 B changes from June 1991 A. Change 2 = Nov. 1995 C changes from Nov. 1992 B. Change 3 = Sept. 1996 D changes from Nov. 1995 C. Ordering Information bq3287 MT Temperature: blank = Commercial (0 to +70°C) I = Extended* (-20 to +70°C) Package Option: MT = T-type module RAM Clear Option: A = RAM clear on pin 21 no mark = No connect on pin 21 Device: bq3287 Real-Time Clock Module *Contact factory for availability. Sept. 1996 D 5 IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. 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