DS1556WP-120

19-5500; Rev 9/10 DS1556 1M, Nonvolatile, Y2K-Compliant Timekeeping RAM www.maxim-ic.com FEATURES   Integrated NV SRAM, Real-Time Clock (RTC), Crystal, Power-Fail Control Circuit, and Lithium Energy Source TOP VIEW RST A16 A14 A12 A7 A6 A5 A4 A3 A2 A1 Clock Registers are Accessed Identically to the Static RAM; These Registers Reside in the 16 Top RAM Locations  Century Byte Register (i.e., Y2K Compliant)  Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power  Precision Power-On Reset  Programmable Watchdog Timer and RTC Alarm  PIN CONFIGURATIONS Battery Voltage-Level Indicator Flag  Power-Fail Write Protection Allows for 10% VCC Power-Supply Tolerance  Also Available in Industrial Temperature Range: -40°C to +85°C VCC A15 DQ0 13 20 DQ6 DQ1 DQ2 14 19 DQ5 15 18 DQ4 GND 16 17 DQ3 IRQ/FT WE A13 A8 A9 A11 OE A10 CE DQ7 Encapsulated DIP  Lithium Energy Source is Electrically Disconnected to Retain Freshness Until Power is Applied for the First Time 32 31 30 29 28 27 26 25 24 23 22 21 A0 BCD-Coded Year, Month, Date, Day, Hours, Minutes, and seconds with Automatic LeapYear Compensation Valid Up to the Year 2100  1 Maxim 2 DS1556 3 4 5 6 7 8 9 10 11 12 IRQ/FT A15 A16 RST VCC WE OE CE DQ7 DQ6 DQ5 DQ4 DQ3 DQ2 DQ1 DQ0 GND 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Maxim DS1556 X1 GND VBAT X2 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 N.C. N.C. A14 A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0 PowerCap Module Board (Uses DS9034PCX PowerCap) Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device may be simultaneously available through various sales channels. For information about device errata, click here: www.maxim-ic.com/errata. 1 of 18 DS1556 1M, Nonvolatile, Y2K-Compliant Timekeeping RAM PIN DESCRIPTION A0–A16 DQ0–DQ7 IRQ/FT RST CE OE WE VCC GND N.C. X1, X2 VBAT - Address Input - Data Input/Outputs - Interrupt, Frequency Test Output (Open Drain) - Power-On Reset Output (Open Drain) - Chip Enable - Output Enable - Write Enable - Power Supply Input - Ground - No Connection - Crystal Connection - Battery Connection ORDERING INFORMATION PART TEMP RANGE VOLTAGE (V) PIN-PACKAGE TOP MARK** DS1556-70+ DS1556-70IND+ DS1556P-70+ DS1556P-70IND+ DS1556W-120+ DS1556W-120IND+ DS1556WP-120+ DS1556WP-120IND+ 0°C to +70°C -40°C to +85°C 0°C to +70°C -40°C to +85°C 0°C to +70°C -40°C to +85°C 0°C to +70°C -40°C to +85°C 5.0 5.0 5.0 5.0 3.3 3.3 3.3 3.3 32 EDIP (0.740a) 32 EDIP (0.740a) 34 PowerCap* 34 PowerCap* 32 EDIP (0.740a) 32 EDIP (0.740a) 34 PowerCap* 34 PowerCap* DS1556+070 DS1556+070 IND DS1556P+70 DS1556P+70 IND DS1556W+120 DS1556W+120 IND DS1556WP+120 DS1556WP+120 IND +Denotes a lead(Pb)-free/RoHS-compliant package. *DS9034-PCX+ or DS9034I-PCX+ required (must be ordered separately). **A “+” in top mark denotes a lead(Pb)-free device. An “IND” anywhere on the top mark indicates an industrial temperature grade device. 2 of 18 DS1556 1M, Nonvolatile, Y2K-Compliant Timekeeping RAM DESCRIPTION The DS1556 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) with an RTC alarm, watchdog timer, power-on reset, battery monitor, and 128k x 8 nonvolatile static RAM. User access to all registers within the DS1556 is accomplished with a byte-wide interface as shown in Figure 1. The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour BCD format. Corrections for day of month and leap year are made automatically. The RTC registers are double-buffered into an internal and external set. The user has direct access to the external set. Clock/calendar updates to the external set of registers can be disabled and enabled to allow the user to access static data. Assuming the internal oscillator is turned on, the internal set of registers is continuously updated, which occurs regardless of external registers settings to guarantee that accurate RTC information is always maintained. The DS1556 has interrupt (IRQ/FT) and reset (RST) outputs which can be used to control CPU activity. The IRQ/FT interrupt output can be used to generate an external interrupt when the RTC register values match user programmed alarm values. The interrupt is always available while the device is powered from the system supply and can be programmed to occur when in the battery-backed state to serve as a system wake-up. Either the IRQ/FT or RST outputs can also be used as a CPU watchdog timer, CPU activity is monitored and an interrupt or reset output will be activated if the correct activity is not detected within programmed limits. The DS1556 power-on reset can be used to detect a system power down or failure and hold the CPU in a safe reset state until normal power returns and stabilizes; the RST output is used for this function. The DS1556 also contains its own power-fail circuitry, which automatically deselects the device when the VCC supply enters an out of tolerance condition. This feature provides a high degree of data security during unpredictable system operation brought on by low VCC levels. PACKAGES The DS1556 is available in two packages (32-pin DIP and 34-pin PowerCap module). The 32-pin DIP style module integrates the crystal, lithium energy source, and silicon all in one package. The 34-pin PowerCap module board is designed with contacts for connection to a separate PowerCap (DS9034PCX) that contains the crystal and battery. This design allows the PowerCap to be mounted on top of the DS1556P after the completion of the surface mount process. Mounting the PowerCap after the surface mount process prevents damage to the crystal and battery due to the high temperatures required for solder reflow. The PowerCap is keyed to prevent reverse insertion. The PowerCap Module board and PowerCap are ordered separately and shipped in separate containers. The part number for the PowerCap is DS9034PCX. 3 of 18 DS1556 1M, Nonvolatile, Y2K-Compliant Timekeeping RAM Figure 1. Block Diagram Maxim DS1556 Table 1. Operating Modes VCC VCC > VPF VSO < VCC