19-6078; Rev 11/11 DS1248/DS1248P 1024K NV SRAM with Phantom Clock FEATURES PIN CONFIGURATIONS Real-Time Clock (RTC) Keeps Track of Hundredths of Seconds, Minutes, Hours, Days, Date of the Month, Months, and Years 128K x 8 NV SRAM Directly Replaces Volatile Static RAM or EEPROM Embedded Lithium Energy Cell Maintains Calendar Operation and Retains RAM Data Watch Function is Transparent to RAM Operation Automatic Leap Year Compensation Valid Up to 2100 Full 10% Operating Range Over 10 Years of Data Retention in the Absence of Power Lithium Energy Source is Electrically Disconnected to Retain Freshness Until Power is Applied for the First Time DIP Module Only TOP VIEW RST A16 A14 A12 A7 A6 A5 A4 A3 A2 A1 Underwriters Laboratories (UL) Recognized (www.maxim-ic.com/qa/info/ul/) PowerCap Module Board Only Surface Mountable Package for Direct Connection to PowerCap Containing Battery and Crystal Replaceable Battery (PowerCap) Pin-for-Pin Compatible with DS1244P and DS1251P 32 31 30 29 28 27 26 25 24 23 22 21 VCC A15 N.C. DQ0 13 20 DQ6 DQ1 DQ2 14 19 DQ5 15 18 DQ4 16 17 DQ3 A0 GND WE A13 A8 A9 A11 OE A10 CE DQ7 Encapsulated DIP (740-mil Flush) Standard 32-Pin JEDEC Pinout 1 2 3 DS1248 4 5 6 7 8 9 10 11 12 RST A15 A16 N.C. 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 DS1248P X1 GND VBAT X2 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 PowerCap Module Board (Uses DS9034PCX+ PowerCap) 1 of 19 N.C. N.C. A14 A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0 DS1248/DS1248P 1024K NV SRAM with Phantom Clock ORDERING INFORMATION PART TEMP RANGE VCC RANGE DS1248Y-70+ DS1248Y-70IND+ DS1248YP-70+ DS1248W-120+ DS1248W-120IND+ DS1248WP-120+ DS1248WP-120IND+ 0C to +70C -40C to +85C 0C to +70C 0C to +70C -40C to +85C 0C to +70C -40C to +85C 5V 10% 5V 10% 5V 10% 3.3V 10% 3.3V 10% 3.3V 10% 3.3V 10% PIN-PACKAGE 32 EDIP 32 EDIP 34 PowerCap* 32 EDIP 32 EDIP 34 PowerCap* 34 PowerCap* + Denotes a lead(Pb)-free/RoHS-compliant package. * DS9034PCX+ or DS9034I-PCX+ (PowerCap) required. Must be ordered separately. DETAILED DESCRIPTION The DS1248 1024K NV SRAM with phantom clock is a fully static, nonvolatile RAM (organized as 128K words by 8 bits) with a built-in real-time clock. The DS1248 has a self-contained lithium energy source and control circuitry, which constantly monitors VCC for an out-of-tolerance condition. When such a condition occurs, the lithium energy source is automatically switched on and writes protection is unconditionally enabled to prevent garbled data in both the memory and real-time clock. PACKAGES The DS1248 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 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 DS1248P after completion of the surface mount process. Mounting the PowerCap after the surface mount process prevents damage to the crystal and battery because of 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. 2 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock PIN DESCRIPTION EDIP PIN PowerCap NAME 1 1 RST 2 3 4 5 6 7 8 9 10 11 12 23 25 26 27 28 31 13 14 15 17 18 19 20 21 22 24 29 30 32 16 3 32 30 25 24 23 22 21 20 19 18 28 29 27 26 31 2 16 15 14 13 12 11 10 9 8 7 6 4, 33, 34 5 17 A16 A14 A12 A7 A6 A5 A4 A3 A2 A1 A0 A10 A11 A9 A8 A13 A15 DQ0 DQ1 DQ2 DQ3 DQ4 DQ5 DQ6 DQ7 CE OE WE N.C. VCC GND FUNCTION Active-Low Reset Input. This pin has an internal pullup resistor connected to VCC. Address Inputs Data In/Data Out Active-Low Chip-Enable Input Active-Low Output-Enable Input Active-Low Write-Enable Input No Connect Power-Supply Input Ground 3 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock RAM READ MODE The DS1248 executes a read cycle whenever WE (write enable) is inactive (high) and CE (chip enable) is active (low). The unique address specified by the 17 address inputs (A0-A16) defines which of the 128k bytes of data is to be accessed. Valid data will be available to the eight data-output drivers within tACC (access time) after the last address input signal is stable, providing that CE and OE (output enable) access times and states are also satisfied. If OE and CE access times are not satisfied, then data access must be measured from the later occurring signal (CE or OE) and the limiting parameter is either tCO for CE or tOE for OE, rather than address access. RAM WRITE MODE The DS1248 is in the write mode whenever the WE and CE signals are in the active (low) state after address inputs are stable. The latter occurring falling edge of CE or WE will determine the start of the write cycle. The write cycle is terminated by the earlier rising edge of CEor WE. All address inputs must be kept valid throughout the write cycle. WE must return to the high state for a minimum recovery time (tWR) before another cycle can be initiated. The OE control signal should be kept inactive (high) during write cycles to avoid bus contention. However, if the output bus has been enabled (CE and OE active) then WE will disable the outputs in tODW from its falling edge. DATA RETENTION MODE The 5V device is fully accessible and data can be written or read only when VCC is greater than VPF. However, when VCC is below the power-fail point, VPF (point at which write protection occurs), the internal clock registers and SRAM are blocked from any access. When VCC falls below the battery switch point, VSO (battery supply level), device power is switched from the VCC pin to the backup battery. RTC operation and SRAM data are maintained from the battery until VCC is returned to nominal levels. The 3.3V device is fully accessible and data can be written or read only when VCC is greater than VPF. When VCC falls below VPF, access to the device is inhibited. If VPF is less than VBAT, the device power is switched from VCC to the backup supply (VBAT) when VCC drops below VPF. If VPF is greater than VBAT, the device power is switched from VCC to the backup supply (VBAT) when VCC drops below VBAT. RTC operation and SRAM data are maintained from the battery until VCC is returned to nominal levels. All control, data, and address signals must be powered down when VCC is powered-down. 4 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock PHANTOM CLOCK OPERATION Communication with the phantom clock is established by pattern recognition on a serial bit stream of 64 bits, which must be matched by executing 64 consecutive write cycles containing the proper data on DQ0. All accesses that occur prior to recognition of the 64-bit pattern are directed to memory. After recognition is established, the next 64 read or write cycles either extract or update data in the phantom clock, and memory access is inhibited. Data transfer to and from the timekeeping function is accomplished with a serial bit stream under control of chip enable, output enable, and write enable. Initially, a read cycle to any memory location using the CE and OE control of the phantom clock starts the pattern recognition sequence by moving a pointer to the first bit of the 64-bit comparison register. Next, 64 consecutive write cycles are executed using the CE and WE control of the SmartWatch. These 64 write cycles are used only to gain access to the phantom clock. Therefore, any address to the memory in the socket is acceptable. However, the write cycles generated to gain access to the phantom clock are also writing data to a location in the mated RAM. The preferred way to manage this requirement is to set aside just one address location in RAM as a phantom clock scratch pad. When the first write cycle is executed, it is compared to bit 0 of the 64-bit comparison register. If a match is found, the pointer increments to the next location of the comparison register and awaits the next write cycle. If a match is not found, the pointer does not advance and all subsequent write cycles are ignored. If a read cycle occurs at any time during pattern recognition, the present sequence is aborted and the comparison register pointer is reset. Pattern recognition continues for a total of 64 write cycles as described above until all the bits in the comparison register have been matched (Figure 1). With a correct match for 64 bits, the phantom clock is enabled and data transfer to or from the timekeeping registers can proceed. The next 64 cycles will cause the phantom clock to either receive or transmit data on DQ0, depending on the level of the OE pin or the WE pin. Cycles to other locations outside the memory block can be interleaved with CE cycles without interrupting the pattern recognition sequence or data transfer sequence to the phantom clock. PHANTOM CLOCK REGISTER INFORMATION The phantom clock information is contained in eight registers of 8 bits, each of which is sequentially accessed 1 bit at a time after the 64-bit pattern recognition sequence has been completed. When updating the phantom clock registers, each register must be handled in groups of 8 bits. Writing and reading individual bits within a register could produce erroneous results. These read/write registers are defined in Figure 2. Data contained in the phantom clock register is in binary-coded decimal format (BCD). Reading and writing the registers is always accomplished by stepping through all eight registers, starting with bit 0 of register 0 and ending with bit 7 of register 7. 5 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock Figure 1. Phantom Clock Register Definition NOTE: THE PATTERN RECOGNITION IN HEX IS C5, 3A, A3, 5C, C5, 3A, A3, 5C. THE ODDS OF THIS PATTERN BEING ACCIDENTALLY DUPLICATED AND CAUSING INADVERTENT ENTRY TO THE PHANTOM CLOCK IS LESS THAN 1 IN 1019. THIS PATTERN IS SENT TO THE PHANTOM CLOCK LSB TO MSB. 6 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock Figure 2. Phantom Clock Register Definition AM/PM/12/24-MODE Bit 7 of the hours register is defined as the 12-hour or 24-hour mode-select bit. When high, the 12-hour mode is selected. In the 12-hour mode, bit 5 is the AM/PM bit with logic high being PM. In the 24-hour mode, bit 5 is the 20-hour bit (20-23 hours). OSCILLATOR AND RESET BITS Bits 4 and 5 of the day register are used to control the RST and oscillator functions. Bit 4 controls the RST (pin 1). When the RST bit is set to logic 1, the RST input pin is ignored. When the RST bit is set to logic 0, a low input on the RST pin will cause the phantom clock to abort data transfer without changing data in the watch registers. Bit 5 controls the oscillator. When set to logic 1, the oscillator is off. When set to logic 0, the oscillator turns on and the watch becomes operational. These bits are shipped from the factory set to a logic 1. 7 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock ZERO BITS Registers 1, 2, 3, 4, 5, and 6 contain one or more bits, which will always read logic 0. When writing these locations, either a logic 1 or 0 is acceptable. BATTERY LONGEVITY The DS1248 has a lithium power source that is designed to provide energy for clock activity and clock and RAM data retention when the VCC supply is not present. The capability of this internal power supply is sufficient to power the DS1248 continuously for the life of the equipment in which it is installed. For specification purposes, the life expectancy is 10 years at +25C with the internal clock oscillator running in the absence of VCC power. Each DS1248 is shipped from Maxim with its lithium energy source disconnected, guaranteeing full energy capacity. When VCC is first applied at a level greater than VPF, the lithium energy source is enabled for battery-backup operation. Actual life expectancy of the DS1248 will be much longer than 10 years since no lithium battery energy is consumed when VCC is present. See "Conditions of Acceptability" at www.maxim-ic.com/TechSupport/QA/ntrl.htm CLOCK ACCURACY (DIP MODULE) The DS1248 is guaranteed to keep time accuracy to within 1 minute per month at +25C. The clock is calibrated at the factory by Maxim using special calibration nonvolatile tuning elements and does not require additional calibration. For this reason, methods of field clock calibration are not available and not necessary. CLOCK ACCURACY (POWERCAP MODULE) The DS1248P and DS9034PCX are each individually tested for accuracy. Once mounted together, the module will typically keep time accuracy to within 1.53 minutes per month (35ppm) at +25C. 8 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock ABSOLUTE MAXIMUM RATINGS Voltage Range on Any Pin Relative to Ground (5V product).............................-0.3V to +6.0V (3.3V product)..................... .....-0.3V to +4.6V Storage Temperature Range EDIP ..........................................................................................................................-40C to +85C PowerCap ................................................................................................................-55C to +125C Lead Temperature (soldering, 10s) ................................................................................................... +260C Note: EDIP is wave or hand-soldered only. Soldering Temperature (reflow, PowerCap) ......................................................................................+260C This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time can affect reliability. OPERATING RANGE TEMP RANGE (NONCONDENSING) 0C to +70C -40C to +85C RANGE Commercial Industrial VCC (V) 3.3 10% or 5 10% 3.3 10% or 5 10% RECOMMENDED OPERATING CONDITIONS Over the Operating Range PARAMETER Logic 1 Logic 0 VCC = 5V 10% VCC = 3.3V 10% VCC = 5V 10% VCC = 3.3V 10% SYMBOL MIN VIH VIL TYP MAX UNITS NOTES V 11 V 11 MAX UNITS NOTES 12 2.2 VCC + 0.3 2.0 VCC + 0.3 -0.3 -0.3 +0.8 +0.6 DC ELECTRICAL CHARACTERISTICS Over the Operating Range (5V) PARAMETER Input Leakage Current I/O Leakage Current CE VIH VCC Output Current at 2.4V Output Current at 0.4V Standby Current CE = 2.2V SYMBOL MIN IIL -1.0 +1.0 A IIO -1.0 +1.0 A IOH IOL ICCS1 -1.0 2.0 5 10 mA mA mA 3.0 5.0 mA 4.37 85 4.50 mA V 11 V 11 Standby Current CE = VCC - 0.5V ICCS2 Operating Current tCYC = 70ns Write Protection Voltage ICC01 VPF Battery Switchover Voltage VSO 4.25 TYP VBAT 9 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock DC ELECTRICAL CHARACTERISTICS Over the Operating Range (3.3V) PARAMETER SYMBOL Input Leakage Current IIL I/O Leakage Current IIO CE VIH VCC Output Current at 2.4V IOH Output Current at 0.4V IOL Standby Current CE = 2.2V ICCS1 Standby Current ICCS2 CE = VCC - 0.5V Operating Current tCYC = 70ns ICC01 Write Protection Voltage VPF Battery Switchover Voltage MIN -1.0 TYP MAX +1.0 UNITS +1.0 A 5 7 mA mA mA 2.0 3.0 mA 50 2.97 mA V 11 V 11 UNITS pF pF NOTES -1.0 -1.0 2.0 2.80 2.86 VBAT or VPF VSO A NOTES 12 CAPACITANCE (TA = +25C) PARAMETER Input Capacitance Input/Output Capacitance SYMBOL CIN CI/O MIN TYP 5 5 MAX 10 10 MEMORY AC ELECTRICAL CHARACTERISTICS Over the Operating Range (5V) PARAMETER Read Cycle Time Access Time OE to Output Valid CE to Output Valid OE or CE to Output Active Output High-Z from Deselection Output Hold from Address Change Write Cycle Time Write Pulse Width Address Setup Time Write Recovery Time Output High-Z from WE Output Active from WE Data Setup Time Data Hold Time from WE SYMBOL tRC tACC tOE tCO tCOE tOD tOH tWC tWP tAW tWR tODW tOEW tDS tDH DS1248Y-70 MIN MAX 70 70 35 70 5 25 5 70 50 0 0 25 5 30 5 10 of 19 UNITS ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns NOTES 5 5 3 5 5 4 4 DS1248/DS1248P 1024K NV SRAM with Phantom Clock PHANTOM CLOCK AC ELECTRICAL CHARACTERISTICS Over the Operating Range (5V) PARAMETER Read Cycle Time CE Access Time OE Access Time CE to Output Low-Z OE to Output Low-Z CE to Output High-Z OE to Output High-Z Read Recovery Write Cycle Time Write Pulse Width Write Recovery Data Setup Time Data Hold Time CE Pulse Width RST Pulse Width SYMBOL MIN tRC tCO tOE tCOE tOEE tOD tODO tRR tWC tWP tWR tDS tDH tCW tRST 65 TYP MAX 55 55 5 5 25 25 10 65 55 10 30 0 60 65 UNITS ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns NOTES 5 5 3 10 4 4 POWER-DOWN/POWER-UP TIMING Over the Operating Range (3.3V) PARAMETER SYMBOL CE at VIH before Power-Down MIN TYP MAX UNITS tPD 0 s tF 300 s tFB 10 s VCC Slew from VPF(max) to VPF(min)(CE at VPF) tR 0 s CE at VIH after Power-Up tREC 1.5 SYMBOL tDR MIN 10 VCC Slew from VPF(max) to VPF(min)( CE at VPF) VCC Slew from VPF(min) to VSO (TA = +25C) PARAMETER Expected Data-Retention Time TYP 2.5 ms MAX UNITS years NOTES NOTES 9 Warning: Under no circumstances are negative undershoots of any amplitude allowed when device is in battery-backup mode. 11 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock MEMORY AC ELECTRICAL CHARACTERISTICS Over the Operating Range (3.3V) PARAMETER Read Cycle Time Access Time OE to Output Valid CE to Output Valid OE or CE to Output Active Output High-Z from Deselection Output Hold from Address Change Write Cycle Time Write Pulse Width Address Setup Time Write Recovery Time Output High-Z from WE Output Active from WE Data Setup Time Data Hold Time from WE SYMBOL tRC tACC tOE tCO tCOE tOD tOH tWC tWP tAW tWR tODW tOEW tDS tDH DS1248W-120 MIN MAX 120 120 60 120 5 40 5 120 90 0 20 40 5 50 20 UNITS ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns NOTES 5 5 3 10 5 5 4 4 PHANTOM CLOCK AC ELECTRICALCHARACTERISTICS Over the Operating Range (3.3V) PARAMETER Read Cycle Time CE Access Time OE Access Time CE to Output Low-Z OE to Output Low-Z CE to Output High-Z OE to Output High-Z Read Recovery Write Cycle Time Write Pulse Width Write Recovery Data Setup Time Data Hold Time CE Pulse Width RST Pulse Width SYMBOL tRC tCO tOE tCOE tOEE tOD tODO tRR tWC tWP tWR tDS tDH tCW tRST 12 of 19 MIN 120 5 5 20 120 100 20 45 0 105 120 TYP MAX 100 100 40 40 UNITS ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns NOTES 5 5 3 10 4 4 DS1248/DS1248P 1024K NV SRAM with Phantom Clock POWER-DOWN/POWER-UP TIMING Over the Operating Range (3.3V) PARAMETER CE at VIH before Power-Down VCC Slew from VPF(MAX) to VPF(MIN)(CE at VIH) VCC Slew from VPF(MAX) to VPF(MIN)(CE at VIH) CE at VIH after Power-Up (TA = +25C) PARAMETER Expected Data-Retention Time SYMBOL tPD tF MIN 0 300 tR 0 tREC 1.5 SYMBOL MIN tDR 10 TYP MAX UNITS NOTES s s s TYP 2.5 ms MAX UNITS NOTES years 9 Warning: Under no circumstances are negative undershoots, of any amplitude, allowed when device is in battery-backup mode. MEMORY READ CYCLE (Note 1) 13 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock MEMORY WRITE CYCLE 1 (Notes 2, 6, and 7) MEMORY WRITE CYCLE 2 (Notes 2 and 8) 14 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock RESET FOR PHANTOM CLOCK READ CYCLE TO PHANTOM CLOCK WRITE CYCLE TO PHANTOM CLOCK 15 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock POWER-DOWN/POWER-UP CONDITION (5V) POWER-DOWN/POWER-UP CONDITION (3.3V) 16 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock AC TEST CONDITIONS Output Load: 50pF + 1TTL Gate Input Pulse Levels: 0 to 3V Timing Measurement Reference Levels Input: 1.5V Output: 1.5V Input Pulse Rise and Fall Times: 5ns NOTES: 1) WE is high for a read cycle. 2) OE = VIH or VIL. If CE = VIH during write cycle, the output buffers remain in a high impedance state. 3) tWP is specified as the logical AND of CE and WE. tWP is measured from the latter of CE or WE going low to the earlier of CE or WE going high. 4) tDH, tDS are measured from the earlier of CE or WE going high. 5) These parameters are sampled with a 50pF load and are not 100% tested. 6) If the CE low transition occurs simultaneously with or later than the WE low transition in Write Cycle 1, the output buffers remain in a high-impedance state during this period. 7) If the CE high transition occurs prior to or simultaneously with the WE high transition, the output buffers remain in a high-impedance state during this period. 8) If WE is low or the WE low transition occurs prior to or simultaneously with the CE low transition, the output buffers remain in a high impedance state during this period. 9) The expected tDR is defined as cumulative time in the absence of VCC with the clock oscillator running. 10) tWR is a function of the latter occurring edge of WE or CE. 11) Voltages are referenced to ground. 12) RST (Pin 1) has an internal pullup resistor. 13) RTC modules can be successfully processed through conventional wave-soldering techniques as long as temperature exposure to the lithium energy source contained within does not exceed +85C. Postsolder cleaning with water-washing techniques is acceptable, provided that ultrasonic vibration is not used. See the PowerCap package drawing for details regarding the PowerCap package. 17 of 19 DS1248/DS1248P 1024K NV SRAM with Phantom Clock PACKAGE INFORMATION For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE 32 EDIP 34 PWRCP PACKAGE CODE MDT32+2 PC2+3 OUTLINE NO. 21-0245 21-0246 18 of 19 LAND PATTERN NO. -- -- DS1248/DS1248P 1024K NV SRAM with Phantom Clock REVISION HISTORY REVISION DATE 11/11 DESCRIPTION Updated the Features, Ordering Information, AM/PM/12/24-MODE, Absolute Maximum Ratings, and Package Information sections PAGES CHANGED 1, 2, 7, 9, 18 19 of 19 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. M a x i m I n t e g r a t e d P r o d u c t s , 1 2 0 S a n G a b r i e l D r iv e , S u n n y v a le , C A 9 4 0 8 6 4 0 8- 7 3 7 - 7 6 0 0 (c) 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.