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PRELIMINARY
DS1244/DS1244P 256K NV SRAM with Phantom Clock
www.dalsemi.com
FEATURES
* * * * * * * * * * * Real time clock keeps track of hundredths of seconds, minutes, hours, days, date of the month, months, and years 32K 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 =Month and year determine the number of days in each month; valid up to 2100 =Full 10% operating range =Operating temperature range 0C to 70C 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 - Standard 28-pin JEDEC pinout PowerCap Module Board only - Surface mountable package for direct connection to PowerCap containing battery and crystal - Replaceable battery (PowerCap) - Pin for pin compatible with DS1248P and DS1251P
PIN ASSIGNMENT
A14/RST A12 A7 A6 A5 A4 A3 A2 A1 A0 DQ0 DQ1 DQ2 DQ3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 VCC WE A13 A8 A9 A11 OE A10 CE DQ7 DQ6 DQ5 DQ4 DQ3
28-Pin Encapsulated Package 740-Mil Extended
NC 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
X1
GND VBAT
X2
34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18
NC NC A14 A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0
34-PIN POWERCAP MODULE BOARD (USES DS9034PCX POWERCAP)
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012500
DS1244/DS1244P
ORDERING INFORMATION
DS1244YP-XXX (5 Volt) -70 70 ns access -100 100 ns access blank P 28-pin DIP Module 34-pin PowerCap Module
PIN DESCRIPTION
A0-A14
CE OE WE
board* DS1244WP-XXX (3.3 Volt) -120 120 ns access -150 150 ns access blank 28-pin DIP Module P 34-pin PowerCap Module board* *DS9034PCX (PowerCap) Required: (must be ordered separately)
VCC GND DQ0-DQ7 NC X1,X2 VBAT
RST
- Address Inputs - Chip Enable - Output Enable - Write Enable - Power Supply Input - Ground - Data In/Data Out - No Connection - Crystal Connection - Battery Connection - Reset
DESCRIPTION
The DS1244 256K NV SRAM with Phantom Clock is a fully static nonvolatile RAM (organized as 32K words by 8 bits) with a built-in real time clock. The DS1244 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 write protection is unconditionally enabled to prevent garbled data in both the memory and real time clock. The Phantom Clock provides timekeeping information including hundredths of seconds, seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with less than 31 days, including correction for leap years. The Phantom Clock operates in either 24-hour or 12-hour format with an AM/PM indicator.
PACKAGES
The DS1244 is available in two packages (28-pin DIP and 34-Pin PowerCap module). The 28-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 DS1244P 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.
RAM READ MODE
The DS1244 executes a read cycle whenever WE(Write Enable) is inactive (high) and CE (Chip Enable) is active (low). The unique address specified by the 15 address inputs (A0-A14) defines which of the 32,768 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. 2 of 19
DS1244/DS1244P
RAM WRITE MODE
The DS1244 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 CE or 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 5 volt 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 3.3 volt device is fully accessible and data can be written or read only when VCC is greater than VPF . When VCC fall as below the power fail point, 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.
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 which 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 ( CE ), Output Enable ( OE ), and Write Enable ( WE ). 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 (this bit pattern is shown in 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 3 of 19
DS1244/DS1244P
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.
PHANTOM CLOCK REGISTER DEFINITION Figure 1
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. 4 of 19
DS1244/DS1244P
PHANTOM CLOCK REGISTER DEFINITION Figure 2
AM-PM/12/24 MODE
Bit 7 of the hours register is defined as the 12- 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 second 10-hour bit (20-23 hours).
OSCILLATOR AND RESET BITS
Bits 4 and 5 of the day register are used to control the RESET and oscillator functions. Bit 4 controls the RESET (pin 1). When the RESET bit is set to logic 1, the RESET input pin is ignored. When the RESET bit is set to logic 0, a low input on the RESET 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.
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. 5 of 19
DS1244/DS1244P
BATTERY LONGEVITY
The DS1244 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 DS1244 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 DS1244 is shipped from Dallas Semiconductor 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 DS1244 will be much longer than 10 years since no lithium battery energy is consumed when VCC is present.
CLOCK ACCURACY (DIP MODULE)
The DS1244 is guaranteed to keep time accuracy to within 1 minute per month at 25C. The clock is calibrated at the factory by Dallas Semiconductor using special calibration nonvolatile tuning elements. The DS1244 does not require additional calibration and temperature deviations will have a negligible effect in most applications. For this reason, methods of field clock calibration are not available and not necessary.
CLOCK ACCURACY (POWERCAP MODULE)
The DS1244P and DS9034PCX are each individually tested for accuracy. Once mounted together, the module is guaranteed to keep time accuracy to within 1.53 minutes per month (35 ppm) at 25C.
ABSOLUTE MAXIMUM RATINGS*
Voltage on Any Pin Relative to Ground Operating Temperature Storage Temperature Soldering Temperature * -0.3V to +7.0V 0C to 70C -40C to +70C 260C for 10 seconds (See Note 13)
This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.
RECOMMENDED DC OPERATING CONDITIONS
PARAMETER Power Supply Voltage Input Logic 1 Input Logic 2 SYMBOL VCC VIH VIL MIN 4.5 2.2 0.3 TYP 5.0 MAX 5.5 VCC+0.3V 0.8 V V V
(0C to 70C)
UNITS NOTES 11 11 11
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DS1244/DS1244P
DC ELECTRICAL CHARACTERISTICS
PARAMETER Input Leakage Current I/O Leakage Current CE V IH[ V CC Output Current @ 2.4 volts Output Current @ 0.4 volts Standby Current CE = 2.2 volts Standby Current CE = VCC - 0.5 volts Operating Current tCYC = 70ns Write Protection Voltage Battery Switch Over Voltage SYMBOL I IL I IO IOH IOL ICCS1 ICCS2 ICC01 VPF VSO 4.25 MIN -1.0 -1.0 -1.0 2.0
(0C to 70C; VCC = 5V =10%)
TYP MAX +1.0 +1.0 UNITS A A mA mA mA mA mA V V 11 11 NOTES 12
5 3.0
10 5.0 85
4.37 VBAT
4.50
DC ELECTRICAL CHARACTERISTICS
PARAMETER Input Leakage Current I/O Leakage Current CE V IH[ V CC Output Current @ 2.4 volts Output Current @ 0.4 volts Standby Current CE = 2.2 volts Standby Current CE = VCC - 0.5 volts Operating Current tCYC = 70ns Write Protection Voltage Battery Switch Over Voltage SYMBOL I IL I IO IOH IOL ICCS1 ICCS2 ICC01 VPF VSO MIN -1.0 -1.0 -1.0 2.0
(0C to 70C; VCC = 3.3V =10%)
TYP MAX +1.0 +1.0 UNITS A A mA mA mA mA mA V V NOTES 12
5 2.0
7 3.0 50 4.50
4.25 VBAT or VPF
11 11
CAPACITANCE
PARAMETER Input Capacitance Input/Output Capacitance SYMBOL CIN CI/O MIN TYP 5 5 MAX 10 10
(tA = 25C)
UNITS pF pF NOTES
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DS1244/DS1244P
MEMORY AC ELECTRICAL CHARACTERISTICS (0C to 70C; VCC = 5.0V 10%)
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 DS1244Y-70 MIN MAX 70 70 35 70 5 25 5 70 50 0 0 25 5 30 5 DS1244Y-100 MIN MAX 100 100 55 100 5 35 5 100 70 0 0 35 5 40 5 UNITS ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns NOTES
5 5
3
5 5 4 4
PHANTOM CLOCK AC ELECTRICAL CHARACTERISTICS (0C to 70C; VCC = 5.0V10%)
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 RESET Pulse Width SYMBOL tRC tCO tOE tCOE tOEE tOD tODO tRR tWC tWP tWR tDS tDH tCW tRST MIN 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
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DS1244/DS1244P
POWER-DOWN/POWER-UP TIMING
PARAMETER CE at VIH before Power-Down VCC Slew from VPF(max) to VPF(min)( CE at VPF) VCC Slew from VPF(min) to VSO VCC Slew from VPF(max) to VPF(min)( CE at VPF) CE at VIH after Power-Up SYMBOL tPD tF tFB tR tREC MIN 0 300 10 0 1.5 2.5 TYP MAX
VCC = 5.0V 10% UNITS NOTES s s s s ms
(tA = 25C)
PARAMETER Expected Data Retention Time SYMBOL tDR MIN 10 TYP MAX UNITS years NOTES 9
WARNING:
Under no circumstances are negative undershoots, of any amplitude, allowed when device is in battery backup mode.
MEMORY AC ELECTRICAL CHARACTERISTICS (0C to 70C; VCC = 3.3V =10%)
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 DS1244W-120 MIN MAX 120 120 X X X X X 120 X X X X X X X X X X DS1244W-150 MIN MAX 150 150 X X X X X 150 X X X X 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
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DS1244/DS1244P
PHANTOM CLOCK AC ELECTRICAL CHARACTERISTICS (0C to 70C; VCC = 3.3V10%)
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 RESET Pulse Width SYMBOL tRC tCO tOE tCOE tOEE tOD tODO tRR tWC tWP tWR tDS tDH tCW tRST MIN 120 TYP MAX 100 100 5 5 40 40 20 120 100 20 45 0 105 120 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
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 SYMBOL tPD tF tR tREC MIN 0 300 0 1.5 2.5 TYP MAX
VCC = 3.3V 10% UNITS NOTES s s s ms
(tA = 25C)
PARAMETER Expected Data Retention Time SYMBOL tDR MIN 10 TYP MAX UNITS years NOTES 9
WARNING:
Under no circumstances are negative undershoots, of any amplitude, allowed when device is in battery backup mode.
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DS1244/DS1244P
MEMORY READ CYCLE (NOTE 1)
MEMORY WRITE CYCLE 1 (NOTES 2, 6, AND 7)
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DS1244/DS1244P
MEMORY WRITE CYCLE 2 (NOTES 2 AND 8)
RESET FOR PHANTOM CLOCK
READ CYCLE TO PHANTOM CLOCK
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DS1244/DS1244P
WRITE CYCLE TO PHANTOM CLOCK
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DS1244/DS1244P
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DS1244/DS1244P
AC TEST CONDITIONS
Output Load: Input Pulse Levels: 50 pF + 1TTL Gate 0-3 volts Timing Measurement Reference Levels Input: 1.5 volts Output: 1.5 volts Input Pulse Rise and Fall Times: 5 ns
NOTES:
1. WE is high for a read cycle. 2. OE = VIH or VIL . If OE = 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 , t DS are measured from the earlier of CE or WE going high. 5. These parameters are sampled with a 50 pF 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. Voltage are referencd to ground. 12. RST (Pin1) has an internal pull-up resistor. 13. Real-Time Clock 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. Post solder cleaning with water washing techniques is acceptable, provided that ultrasonic vibration is not used. In addition, for the PowerCap: a. Dallas Semiconductor recommends that PowerCap Module bases experience one pass through solder reflow oriented with the label side up ("live - bug"). b. Hand Soldering and touch-up: Do not touch or apply the soldering iron to leads for more than 3 (three) seconds. To solder, apply flux to the pad, heat the lead frame pad and apply solder. To remove the part, apply flux, heatthe lead frame pad until the solder reflow and use a solder wick to remove solder.
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DS1244/DS1244P
DS1244 256K NV SRAM WITH PHANTOM CLOCK
PKG DIM A IN. MM B IN. MM C IN. MM D IN. MM E IN. MM F IN. MM G IN. MM H IN. MM J IN. MM K IN. MM
28-PIN MIN MAX 1.520 1.540 38.61 39.12 0.720 0.740 18.29 18.80 0.395 0.415 10.03 10.54 0.100 0.130 2.54 3.30 0.017 0.030 0.43 0.76 0.120 0.160 3.05 4.06 0.090 0.110 2.29 2.79 0.590 0.630 14.99 16.00 0.008 0.012 0.20 0.30 0.015 0.021 0.38 0.53
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DS1244/DS1244P
DS1244P
PKG DIM A B C D E F G MIN 0.920 0.980 0.052 0.048 0.015 0.025 INCHES NOM 0.925 0.985 0.055 0.050 0.020 0.027 MAX 0.930 0.990 0.080 0.058 0.052 0.025 0.030
NOTE:
Dallas Semiconductor recommends that PowerCap Module bases experience one pass through solder reflow oriented with the label side up ("live - bug"). Hand Soldering and touch-up: Do not touch or apply the soldering iron to leads for more than 3 (three) seconds. To solder, apply flux to the pad, heat the lead frame pad and apply solder. To remove the part, apply flux, heat the lead frame pad until the solder reflows and use a solder wick to remove solder.
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DS1244/DS1244P
DS1244P WITH DS9034PCX ATTACHED
PKG DIM A B C D E F G MIN 0.920 0.955 0.240 0.052 0.048 0.015 0.020 INCHES NOM 0.925 0.960 0.245 0.055 0.050 0.020 0.025 MAX 0.930 0.965 0.250 0.058 0.052 0.025 0.030
COMPONENTS AND PLACEMENT MAY VARY FROM EACH DEVICE TYPE
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DS1244/DS1244P
RECOMMENDED POWERCAP MODULE LAND PATTERN
PKG DIM INCHES MIN NOM 1.050 0.826 0.050 0.030 0.112 MAX -
A B C D E
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