DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs www.maxim-ic.com FEATURES § § § § § § § § § § § PIN CONFIGURATIONS Integrated NV SRAM, Real-Time Clock, Crystal, Power-Fail Control Circuit, and Lithium Energy Source Clock Registers are Accessed Identically to the Static RAM. These Registers are Resident in the Eight Top RAM Locations. Century Byte Register (i.e., Y2K Compliant) Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power BCD-Coded Century, Year, Month, Date, Day, Hours, Minutes, and Seconds with Automatic Leap-Year Compensation Valid Up to the Year 2100 Battery Voltage-Level Indicator Flag Power-Fail Write Protection Allows for ±10% VCC Power-Supply Tolerance Lithium Energy Source is Electrically Disconnected to Retain Freshness Until Power is Applied for the First Time DIP Module Only Standard JEDEC Byte-Wide 32k x 8 Static RAM Pinout PowerCapÒ Module Board Only Surface-Mountable Package for Direct Connection to PowerCap Containing Battery and Crystal Replaceable Battery (PowerCap) Power-On Reset Output Pin-for-Pin Compatible with Other Densities of DS174xP Timekeeping RAM Also Available in Industrial Temperature Range: -40°C to +85°C TOP VIEW A14 A12 A7 A6 A5 A4 A3 A2 A1 A0 DQ0 DQ1 DQ2 GND 1 Dallas 2 Semiconductor DS1744 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 PDIP Module (700-mil Extended) N.C. N.C. N.C. 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 Dallas Semiconductor DS1744P 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) PowerCap is a registered trademark of Dallas Semiconductor. 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 REV: 011204 DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs PIN DESCRIPTION A0–A14 CE OE WE VCC GND DQ0–DQ7 N.C. RST X1, X2 VBAT - Address Input - Chip Enable - Output Enable - Write Enable - Power-Supply Input - Ground - Data Input/Output - No Connection - Power-On Reset Output (PowerCap module board only) - Crystal Connection - Battery Connection ORDERING INFORMATION PART TEMP RANGE DS1744-70 DS1744-70IND DS1744P-70 DS1744P-70IND DS1744W-120 DS1744W-120IND DS1744WP-120 DS1744WP-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 PIN-PACKAGE VOLTAGE (V) 28 PDIP Module 28 PDIP Module 34 PowerCap* 34 PowerCap* 28 DIP Module 28 DIP Module 34 PowerCap* 34 PowerCap* 5 5 5 5 3.3 3.3 3.3 3.3 TOP MARK DS1744-70 DS1744-70IND DS1744P-70 DS1744P-70IND DS1744W-120 DS1744W-120IND DS1744WP-120 DS1744WP-120IND *DS9034PCX (PowerCap) required. (Must be ordered separately.) DESCRIPTION The DS1744 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) and 32k x 8 NV SRAM. User access to all registers within the DS1744 is accomplished with a byte-wide interface as shown in Figure 1. The RTC information and control bits reside in the eight uppermost RAM locations. The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour BCD format. Corrections for the date of each month and leap year are made automatically. The RTC clock registers are double-buffered to avoid access of incorrect data that can occur during clock update cycles. The double-buffered system also prevents time loss as the timekeeping countdown continues unabated by access to time register data. The DS1744 also contains its own power-fail circuitry that deselects the device when the VCC supply is in an out-of-tolerance condition. This feature prevents loss of data from unpredictable system operation brought on by low VCC as errant access and update cycles are avoided. 2 of 18 DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs Figure 1. Block Diagram PACKAGES The DS1744 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 DS1744P after the completion of the surface-mount process. Mounting the PowerCap after the surfacemount 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. CLOCK OPERATIONS—READING THE CLOCK While the double-buffered register structure reduces the chance of reading incorrect data, internal updates to the DS1744 clock registers should be halted before clock data is read to prevent reading of data in transition. However, halting the internal clock register updating process does not affect clock accuracy. Updating is halted when a 1 is written into the read bit, bit 6 of the century register (Table 2). As long as a 1 remains in that position, updating is halted. After a halt is issued, the registers reflect the count, that is, day, date, and time that was current at the moment the halt command was issued. However, the internal clock registers of the double-buffered system continue to update so that the clock accuracy is not affected by the access of data. All the DS1744 registers are updated simultaneously after the internal clock-register updating process has been re-enabled. Updating is within a second after the read bit is written to 0. The READ bit must be a 0 for a minimal of 500ms to ensure the external registers are updated. 3 of 18 DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs Table 1. Truth Table CE VCC VIH VIL VCC > VPF VIL VIL VSO < VCC < VPF X VCC < VSO < VPF X OE X X VIL VIH X X WE X VIL VIH VIH X X MODE Deselect Write Read Read Deselect Deselect DQ High-Z Data In Data Out High-Z High-Z High-Z POWER Standby Active Active Active CMOS Standby Data-Retention Mode SETTING THE CLOCK As shown in Table 2, bit 7 of the century register is the write bit. Setting the write bit to a 1, like the read bit, halts updates to the DS1744 registers. The user can then load them with the correct day, date, and time data in 24-hour BCD format. Resetting the write bit to a 0 then transfers those values to the actual clock counters and allows normal operation to resume. STOPPING AND STARTING THE CLOCK OSCILLATOR The clock oscillator can be stopped at any time. To increase the shelf life, the oscillator can be turned off to minimize current drain from the battery. The OSC bit is the MSB (bit 7) of the seconds registers (Table 2). Setting it to a 1 stops the oscillator. FREQUENCY TEST BIT As shown in Table 2, bit 6 of the day byte is the frequency test bit. When the frequency test bit is set to logic 1 and the oscillator is running, the LSB of the seconds register toggles at 512Hz. When the seconds register is being read, the DQ0 line toggles at the 512Hz frequency as long as conditions for access remain valid (i.e., CE low, OE low, WE high, and address for seconds register remain valid and stable). CLOCK ACCURACY (DIP MODULE) The DS1744 is guaranteed to keep time accuracy to within ±1 minute per month at +25°C. The RTC is calibrated at the factory by Dallas Semiconductor using 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 is also affected by the electrical environment; caution should be taken to place the RTC in the lowest-level EMI section of the PC board layout. For additional information, refer to Application Note 58: Crystal Considerations with Dallas Real-Time Clocks. CLOCK ACCURACY (PowerCap MODULE) The DS1744 and DS9034PCX are individually tested for accuracy. Once mounted together, the module typically keeps time accuracy to within ±1.53 minutes per month (35ppm) at +25°C. Clock accuracy is also affected by the electrical environment and caution should be taken to place the RTC in the lowestlevel EMI section of the PC board layout. For additional information, refer to Application Note 58: Crystal Considerations with Dallas Real-Time Clocks. 4 of 18 DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs Table 2. Register Map ADDRESS 7FFFF 7FFFE 7FFFD 7FFFC 7FFFB 7FFFA 7FFF9 7FFF8 DATA B7 B6 X X BF X X OSC W X X FT X B5 B4 B3 10 Year R 10 Month 10 Date X X 10 Hour 10 Minutes 10 Seconds 10 Century B2 B1 B0 Year Month Date X X Day Hour Minutes Seconds Century OSC = Stop Bit R = Read Bit FT = Frequency Test W = Write Bit X = See Note BF = Battery Flag FUNCTION RANGE Year Month Date Day Hour Minutes Seconds Century 00-99 01-12 01-31 01-07 00-23 00-59 00-59 00-39 NOTE: All indicated “X” bits are not dedicated to any particular function and can be used as normal RAM bits. RETRIEVING DATA FROM RAM OR CLOCK The DS1744 is in the read mode whenever OE (output enable) is low, WE (write enable) is high, and CE (chip enable) is low. The device architecture allows ripple-through access to any of the address locations in the NV SRAM. Valid data is available at the DQ pins within tAA after the last address input is stable, providing that the CE and OE access times and states are satisfied. If CE or OE access times and states are not met, valid data is available at the latter of chip-enable access (tCEA) or at output-enable access time (tOEA). The state of the DQ pins is controlled by CE and OE . If the outputs are activated before tAA, the data lines are driven to an intermediate state until tAA. If the address inputs are changed while CE and OE remain valid, output data remains valid for output-data hold time (tOH) but then goes indeterminate until the next address access. WRITING DATA TO RAM OR CLOCK The DS1744 is in the write mode whenever WE and CE are in their active state. The start of a write is referenced to the latter occurring transition of WE or CE . The addresses must be held valid throughout the cycle. CE or WE must return inactive for a minimum of tWR prior to the initiation of another read or write cycle. Data in must be valid tDS prior to the end of write and remain valid for tDH afterward. In a typical application, the OE signal is high during a write cycle. However, OE can be active provided that care is taken with the data bus to avoid bus contention. If OE is low prior to WE transitioning low, the data bus can become active with read data defined by the address inputs. A low transition on WE then disables the output tWEZ after WE goes active. 5 of 18 DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs 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. At this time the power-fail reset-output signal ( RST ) is driven active and remains active until VCC returns to nominal levels. 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. At this time the power-fail reset-output signal ( RST ) is driven active and remains active until VCC returns to nominal levels. If VPF is less than VSO, the device power is switched from VCC to the backup supply (VBAT) when VCC drops below VPF. If VPF is greater than VSO, the device power is switched from VCC to the backup supply (VBAT) when VCC drops below VSO. RTC operation and SRAM data are maintained from the battery until VCC is returned to nominal levels. The RST signal is an open-drain output and requires a pullup. Except for the RST , all control, data, and address signals must be powered down when VCC is powered down. BATTERY LONGEVITY The DS1744 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 DS1744 continuously for the life of the equipment in which it is installed. For specification purposes, the life expectancy is 10 years at +25°C with the internal clock oscillator running in the absence of VCC power. Each DS1744 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 DS1744 is much longer than 10 years since no lithium battery energy is consumed when VCC is present. BATTERY MONITOR The DS1744 constantly monitors the battery voltage of the internal battery. The battery flag bit (bit 7) of the day register is used to indicate the voltage-level range of the battery. This bit is not writable and should always be a 1 when read. If a 0 is ever present, an exhausted lithium energy source is indicated, and both the contents of the RTC and RAM are questionable. 6 of 18 DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs ABSOLUTE MAXIMUM RATINGS Voltage Range on Any Pin Relative to Ground……………………..………………………………………..-0.3V to +6.0V Operating Temperature Range……………………………………...………………………………………...-40°C to +85°C Storage Temperature Range…………………………………………………………………………………..-40°C to +85°C Soldering Temperature…………………………………………….See IPC/JEDEC J-STD-020A (DIP Package) (Note 7) This is a stress rating only and functional operation of the device at these or any other condition 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 RANGE Commercial Industrial TEMP RANGE 0°C to +70°C -40°C to +85°C VCC 3.3V ±10% or 5V ±10% 3.3V ±10% or 5V ±10% RECOMMENDED DC OPERATING CONDITIONS (TA = Over the operating range) PARAMETER Logic 1 Voltage (All Inputs) VCC = 5V ±10% VCC = 3.3V ±10% Logic 0 Voltage (All Inputs) VCC = 5V ±10% VCC = 3.3V ±10% SYMBOL MIN VIH TYP MAX UNITS NOTES 2.2 VCC + 0.3V V 1 VIH 2.0 VCC + 0.3V V VIL -0.3 0.8 V VIL 0.3 0.6 V 1 MAX UNITS NOTES ICC 75 mA 2, 3 ICC1 6 mA 2, 3 Icc2 4 mA 2, 3 DC ELECTRICAL CHARACTERISTICS (VCC = 5.0V ±10%, TA = Over the operating range.) PARAMETER Active Supply Current TTL Standby Current ( CE = VIH) CMOS Standby Current ( CE ³ VCC - 0.2V) Input Leakage Current (Any Input) Output Leakage Current (Any Output) Output Logic 1 Voltage (IOUT = -1.0mA) Output Logic 0 Voltage (IOUT = +2.1mA) SYMBOL MIN TYP IIL -1 +1 mA IOL -1 +1 mA VOH 2.4 1 0.4 VOL Write Protection Voltage VPF Battery Switchover Voltage VSO 4.25 4.50 VBAT 7 of 18 1 V 1 1, 4 DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs DC ELECTRICAL CHARACTERISTICS (VCC = 3.3V ±10%, TA = Over the operating range.) PARAMETER Active Supply Current TTL Standby Current ( CE = VIH) CMOS Standby Current ( CE ³ VCC - 0.2V) Input Leakage Current (Any Input) Output Leakage Current (Any Output) Output Logic 1 Voltage (IOUT = -1.0mA) Output Logic 0 Voltage (IOUT = +2.1mA) SYMBOL MIN TYP MAX UNITS NOTES ICC 30 mA 2, 3 ICC1 2 mA 2, 3 ICC2 2 mA 2, 3 IIL -1 +1 mA IOL -1 +1 mA VOH 2.4 1 0.4 VOL Write Protection Voltage VPF Battery Switchover Voltage VSO 2.80 2.97 VBAT or VPF 1 V 1 V 1, 4 UNITS NOTES AC CHARACTERISTICS—READ CYCLE (5V) (VCC = 5.0V ±10%, TA = Over the operating range.) PARAMETER SYMBOL MIN TYP MAX Read Cycle Time tRC 70 Address Access Time tAA CE to DQ Low-Z tCEL CE Access Time tCEA 70 ns CE Data Off Time tCEZ 25 ns OE to DQ Low-Z tOEL OE Access Time tOEA 35 ns OE Data Off Time tOEZ 25 ns Output Hold from Address tOH ns 70 5 ns 5 5 8 of 18 ns ns ns DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs AC CHARACTERISTICS—READ CYCLE (3.3V) (VCC = 3.3V ±10%, TA = Over the operating range.) PARAMETER SYMBOL MIN TYP MAX Read Cycle Time tRC 120 Address Access Time tAA CE to DQ Low-Z tCEL CE Access Time tCEA 120 ns CE Data Off Time tCEZ 40 ns OE to DQ Low-Z tOEL OE Access Time tOEA 100 ns OE Data Off Time tOEZ 35 ns Output Hold from Address tOH ns 120 5 READ CYCLE TIMING DIAGRAM 9 of 18 ns ns 5 5 UNITS ns ns NOTES DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs AC CHARACTERISTICS—WRITE CYCLE (5V) (VCC = 5.0V ±10%, TA = Over the operating range.) PARAMETER SYMBOL MIN TYP MAX Write Cycle Time tWC 70 ns Address Setup Time tAS 0 ns WE Pulse Width tWEW 50 ns CE Pulse Width tCEW 60 ns Data Setup Time tDS 30 ns Data Hold Time tDH1 0 ns 8 Data Hold Time tDH2 0 ns 9 Address Hold Time tAH1 5 ns 8 Address Hold Time tAH2 5 ns 9 WE Data Off Time tWEZ Write Recovery Time tWR 25 5 UNITS NOTES ns ns AC CHARACTERISTICS—WRITE CYCLE (3.3V) (VCC = 3.3V ±10%, TA = Over the operating range.) PARAMETER SYMBOL MIN TYP MAX Write Cycle Time tWC 120 Address Setup Time tAS 0 WE Pulse Width tWEW 100 ns CE Pulse Width tCEW 110 ns CE and CE2 Pulse Width tCEW 110 ns Data Setup Time tDS 80 ns Data Hold Time tDH1 0 ns 8 Data Hold Time tDH2 0 ns 9 Address Hold Time tAH1 0 ns 8 Address Hold Time tAH2 10 ns 9 WE Data Off Time tWEZ Write Recovery Time tWR 10 of 18 NOTES ns 120 40 10 UNITS ns ns ns DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs WRITE CYCLE TIMING DIAGRAM, WRITE-ENABLE CONTROLLED WRITE CYCLE TIMING DIAGRAM, CHIP-ENABLE CONTROLLED 11 of 18 DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs POWER-UP/DOWN AC CHARACTERISTICS (5V) (VCC = 5.0V ±10%, TA = Over the operating range.) PARAMETER SYMBOL MIN CE or WE at VIH Before Power-Down tPD 0 ms VCC Fall Time: VPF(MAX) to VPF(MIN) tF 300 ms VCC Fall Time: VPF(MIN) to VSO tFB 10 ms VCC Rise Time: VPF(MIN) to VPF(MAX) tR 0 ms Power-Up Recover Time tREC Expected Data-Retention Time (Oscillator ON) tDR 12 of 18 MAX 35 10 POWER-UP/DOWN TIMING (5V DEVICE) TYP UNITS NOTES ms years 5, 6 DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs POWER-UP/DOWN CHARACTERISTICS (3.3V) (VCC = 3.3V ±10%, TA = Over the operating range.) PARAMETER SYMBOL MIN TYP MAX CE or WE at VIH, Before PowerDown tPD 0 ms VCC Fall Time: VPF(MAX) to VPF(MIN) tF 300 ms VCC Rise Time: VPF(MIN) to VPF(MAX) tR 0 ms tREC VPF to RST High Expected Data-Retention Time (Oscillator ON) UNITS 35 10 tDR NOTES ms years 5, 6 POWER-UP/DOWN WAVEFORM TIMING (3.3V DEVICE) CAPACITANCE (TA = +25°C) PARAMETER Capacitance On All Input Pins Capacitance On All Output Pins SYMBOL MIN MAX UNITS CIN 14 pF CO 10 pF 13 of 18 TYP NOTES DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs AC TEST CONDITIONS Output Load: 50pF + 1TTL Gate Input Pulse Levels: 0 to 3.0V Timing Measurement Reference Levels: Input: 1.5V Output: 1.5V Input Pulse Rise and Fall Times: 5ns NOTES: 1) Voltages are referenced to ground. 2) Typical values are at +25°C and nominal supplies. 3) Outputs are open. 4) Battery switchover occurs at the lower of either the battery terminal voltage or VPF. 5) Data-retention time is at +25°C. 6) Each DS1744 has a built-in switch that disconnects the lithium source until the user first applies VCC. The expected tDR is defined for DIP modules and assembled PowerCap modules as a cumulative time in the absence of VCC starting from the time power is first applied by the user. 7) RTC modules (DIP) can be successfully processed through conventional wave-soldering techniques as long as temperature exposure to the lithium energy source contained within does not exceed +85°C. 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 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. 8) tAH1, tDH1 are measured from WE going high. 9) tAH2, tDH2 are measured from CE going high. 14 of 18 DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs PACKAGE INFORMATION (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/DallasPackInfo.) PKG A B C D E F G H J K 15 of 18 DIM IN MM IN MM IN MM IN MM IN MM IN MM IN MM IN MM IN MM IN MM 28-PIN MIN 1.470 37.34 0.675 17.75 0.335 8.51 0.075 1.91 0.015 0.38 0.140 3.56 0.090 2.29 0.590 14.99 0.010 0.25 0.015 0.43 MAX 1.490 37.85 0.740 18.80 0.355 9.02 0.105 2.67 0.030 0.76 0.180 4.57 0.110 2.79 0.630 16.00 0.018 0.45 0.025 0.58 DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs PACKAGE INFORMATION (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/DallasPackInfo.) PKG DIM A B C D E F G IN IN IN IN IN IN IN 34-PIN PowerCap MODULE MIN NOM MAX 0.920 0.925 0.930 0.980 0.985 0.990 — — 0.080 0.052 0.055 0.058 0.048 0.050 0.052 0.015 0.020 0.025 0.025 0.027 0.030 NOTE: DALLAS SEMICONDUCTOR RECOMMENDS THAT POWERCAP MODULE BASES EXPERIENCE ONE PASS THROUGH SOLDER REFLOW ORIENTED WITH THE LABE SIDE UP (“LIVE-BUG”). NOTE: HAND SOLDERING AND TOUCH-UP: DO NOT TOUCH OR APPLY THE SOLDERING IRON TO LEADS FOR MORE THAN 3 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. COMPONENTS AND PLACEMENT MAY VARY FROM EACH DEVICE TYPE. 16 of 18 DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs PACKAGE INFORMATION (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/DallasPackInfo.) DS1744P WITH DS9034PCX ATTACHED PKG DIM A B C D E F G IN IN IN IN IN IN IN MIN 0.920 0.955 0.240 0.052 0.048 0.015 0.020 34-PIN NOM 0.925 0.960 0.245 0.055 0.050 0.020 0.025 COMPONENTS AND PLACEMENT MAY VARY FROM EACH DEVICE TYPE. 17 of 18 MAX 0.930 0.965 0.250 0.058 0.052 0.025 0.030 DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs PACKAGE INFORMATION (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/DallasPackInfo.) RECOMMENDED POWERCAP MODULE LAND PATTERN PKG DIM A B C D E IN IN IN IN IN PowerCap MODULE MIN NOM MAX — 1.050 — — 0.826 — — 0.050 — — 0.030 — — 0.112 — Maxim/Dallas Semiconductor cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim/Dallas Semiconductor product. No circuit patent licenses are implied. Maxim/Dallas Semiconductor reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2004 Maxim Integrated Products · Printed USA 18 of 18