M48T129Y M48T129V 3.3V-5V 1 Mbit (128Kb x8) TIMEKEEPER SRAM ■ INTEGRATED ULTRA LOW POWER SRAM, REAL TIME CLOCK, POWER-FAIL CONTROL CIRCUIT, BATTERY AND CRYSTAL ■ YEAR 2000 COMPLIANT ■ BCD CODED CENTURY, YEAR, MONTH, DAY, DATE, HOURS, MINUTES, and SECONDS ■ BATTERY LOW WARNING FLAG ■ AUTOMATIC POWER-FAIL CHIP DESELECT and WRITE PROTECTION ■ TWO WRITE PROTECT VOLTAGES: (VPFD = Power-fail Deselect Voltage) 32 1 PMDIP32 (PM) Module SNAPHAT (SH) Battery – M48T129Y: 4.2V ≤ VPFD ≤ 4.5V – M48T129V: 2.7V ≤ VPFD ≤ 3.0V ■ CONVENTIONAL SRAM OPERATION; UNLIMITED WRITE CYCLES ■ SOFTWARE CONTROLLED CLOCK CALIBRATION for HIGH ACCURACY APPLICATIONS ■ 10 YEARS of DATA RETENTION and CLOCK OPERATION in the ABSENCE of POWER ■ SELF CONTAINED BATTERY and CRYSTAL in DIP PACKAGE ■ MICROPROCESSOR POWER-ON RESET (Valid even during battery back-up mode) ■ PROGRAMMABLE ALARM OUTPUT ACTIVE in BATTERY BACK-UP MODE ■ SURFACE MOUNT CHIP SET PACKAGING INCLUDES a 44-PIN SOIC and a 32-LEAD TSOP (SNAPHAT TOP TO BE ORDERED SEPARATELY) ■ SOIC PACKAGE PROVIDES DIRECT CONNECTION for a SNAPHAT TOP WHICH CONTAINS the BATTERY and CRYSTAL ■ SNAPHAT HOUSING TSOP32 (8 x 20mm) SOH44 Surface Mount Chip Set Solution (CS) Figure 1. Logic Diagram VCC 17 8 A0-A16 W DQ0-DQ7 M48T129Y M48T129V E RST IRQ/FT G (BATTERY/CRYSTAL) IS REPLACEABLE VSS AI02260 April 2000 1/22 M48T129Y, M48T129V Table 1. Signal Names Figure 2. DIP Connections RST A16 A14 A12 A7 A6 A5 A4 A3 A2 A1 A0 DQ0 DQ1 DQ2 VSS 1 32 2 31 3 30 4 29 5 28 6 27 7 26 8 M48T129Y 25 9 M48T129V 24 10 23 11 22 12 21 13 20 14 19 15 18 16 17 VCC A15 IRQ/FT W A13 A8 A9 A11 G A10 E DQ7 DQ6 DQ5 DQ4 DQ3 A0-A16 Address Inputs DQ0-DQ7 Data Inputs / Outputs E Chip Enable Input G Output Enable Input W Write Enable Input RST Reset Output (open drain) IRQ/FT Interrupt / Frequency Test Output (open drain) VCC Supply Voltage VSS Ground AI02261 Table 2. Absolute Maximum Ratings (1) Symbol TA TSTG Parameter Value Unit 0 to 70 °C –40 to 85 °C –0.3 to VCC+0.3 V M48T129Y –0.3 to 7.0 V M48T129V –0.3 to 4.6 V Ambient Operating Temperature Storage Temperature (VCC Off, Oscillator Off) VIO Input or Output Voltages VCC Supply Voltage IO Output Current 20 mA PD Power Dissipation 1 W Note: 1. Stresses greater than those listed under ”Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to the absolute maximum rating conditions for extended periods of time may affect reliability. 2. Soldering temperature not to exceed 260°C for 10 seconds (total thermal budget not to exceed 150°C for longer than 30 seconds). CAUTION: Negative undershoots below –0.3V are not allowed on any pin while in the Battery Back-up mode. DESCRIPTION The M48T129Y/V TIMEKEEPER RAM is a 128Kb x 8 non-volatile static RAM and real time clock, with programmable alarms and a watchdog timer. The special DIP package provides a fully integrated battery back-up memory and real time clock solution. The M48T129Y/V directly replaces industry standard 128Kb x 8 SRAM. It also provides the non-volatility of Flash without any requirement for special write timing or limitations on the number of writes that can be performed. 2/22 For surface mount environments ST provides a Chip Set solution consisting of a 44 pin 330mil SOIC TIMEKEEPER Supervisor (M48T201V/Y) and a 32 pin TSOP (8 x 20mm) LPSRAM (M68Z128/W) packages. The 44 pin 330mil SOIC provides sockets with gold plated contacts at both ends for direct connection to a separate SNAPHAT housing containing the battery. The unique design allows the SNAPHAT battery package to be mounted on top of the SOIC package after the completion of the surface mount pro- M48T129Y, M48T129V Figure 3. Block Diagram 16 x 8 TIMEKEEPER REGISTERS OSCILLATOR AND CLOCK CHAIN 32,768 Hz CRYSTAL RST IRQ/FT POWER A0-A16 131,056 x 8 SRAM ARRAY LITHIUM CELL VOLTAGE SENSE AND SWITCHING CIRCUITRY VCC cess. Insertion of the SNAPHAT housing after reflow prevents potential battery damage due to the high temperatures required for device surfacemounting. The SNAPHAT housing is keyed to prevent reverse insertion. The SNAPHAT battery package is shipped separately in plastic anti-static tubes or in Tape & Reel form. The part number is ”M4Txx-BR12SH1”. The 32 pin 600 mil DIP Hybrid houses a controller chip, SRAM, quartz crystal, and a long life lithium button cell in a single package. Figure 3 illustrates the static memory array and the quartz controlled clock oscillator. The clock locations contain the century, year, month, date, day, hour, minute, and second in 24 hour BCD format. Corrections for 28, 29 (leap year), 30, and 31 day months are made automatically. The nine clock bytes (1FFFFh-1FFF9h and 1FFF1h) are not the actual clock counters, they are memory locations consisting of BiPORT read/write memory cells within the static RAM array. The M48T129Y/V includes a clock control circuit which updates the clock bytes with current information once per second. The information can be accessed by the user in the same manner as any other location in the static memory array. Byte DQ0-DQ7 E VPFD W G VSS AI02583 1FFF8h is the clock control register. This byte controls user access to the clock information and also stores the clock calibration setting. Byte 1FFF7h contains the watchdog timer setting. The watchdog timer can generate either a reset or an interrupt, depending on the state of the Watchdog Steering bit (WDS). Bytes 1FFF6h-1FFF2h include bits that, when programmed, provide for clock alarm functionality. Alarms are activated when the register content matches the month, date, hours, minutes, and seconds of the clock registers. Byte 1FFF1h contains century information. Byte 1FFF0h contains additional flag information pertaining to the watchdog timer, the alarm condition and the battery status. The M48T129Y/V also has its own Power-Fail Detect circuit. This control circuitry constantly monitors the supply voltage for an out of tolerance condition. When VCC is out of tolerance, the circuit write protects the TIMEKEEPER register data and external SRAM, providing data security in the midst of unpredictable system operation. As VCC falls, the control circuitry automatically switches to the battery, maintaining data and clock operation until valid power is restored. 3/22 M48T129Y, M48T129V Figure 4. Hardware Hookup for SMT Chip Set (1) SNAPHAT (3) BATTERY/CRYSTAL A0-A16 32,768 Hz CRYSTAL A0-A16 VCC VOUT 0.1µF 5V LITHIUM CELL M48T201Y/V (2) VCC 0.1µF M68Z128/W (2) E W ECON G E W WDI GCON RSTIN1 RST RSTIN2 IRQ/FT VSS SQW G VSS DQ0-DQ7 DQ0-DQ7 AI03632 Note: 1. For pin connections, see individual data sheets for M48T201Y/V and M68Z128/W at www.st.com. 2. For 5V, M48T129Y (M48T201Y + M68Z128). For 3.3V, M48T129V (M48T201V + M68Z128W). 3. SNAPHAT Top ordered separately. READ MODE The M48T129Y/V is in the Read Mode whenever W (Write Enable) is high and E (Chip Enable) is low. The unique address specified by the 17 Address Inputs defines which one of the 131,072 bytes of data is to be accessed. Valid data will be available at the Data I/O pins within tAVQV (Address Access Time) after the last address input signal is stable, providing the E and G access times are also satisfied. If the E and G access times are not met, valid data will be available after the latter of the Chip Enable Access Times (tELQV) or Output Enable Access Time (tGLQV). The state of the eight three-state Data I/O signals is controlled by E and G. If the outputs are activated before tAVQV, the data lines will be driven to an indeterminate state until tAVQV. If the Address Inputs are changed while E and G remain active, output data will remain valid for tAXQX (Output 4/22 Data Hold Time) but will go indeterminate until the next Address Access. WRITE MODE The M48T129Y/V is in the Write Mode whenever W (Write Enable) and E (Chip Enable) are low state after the address inputs are stable. The start of a write is referenced from the latter occurring falling edge of W or E. A write is terminated by the earlier rising edge of W or E. The addresses must be held valid throughout the cycle. E or W must return high for a minimum of tEHAX from Chip Enable or tWHAX from Write Enable prior to the initiation of another read or write cycle. Data-in must be valid tDVWH prior to the end of write and remain valid for t WHDX afterward. G should be kept high during write cycles to avoid bus contention; although, if the output bus has been activated by a low on E and G a low on W will disable the outputs tWLQZ after W falls. M48T129Y, M48T129V Table 3. Operating Modes (1) Mode VCC Deselect Write Read 4.5V to 5.5V or 3.0V to 3.6V Read Deselect VSO to VPFD (min) Deselect ≤ VSO (2) (2) E G W DQ0-DQ7 Power VIH X X High Z Standby VIL X VIL D IN Active VIL VIL VIH DOUT Active VIL VIH VIH High Z Active X X X High Z CMOS Standby X X X High Z Battery Back-up Mode Note: 1. X = VIH or VIL; VSO = Battery Back-up Switchover Voltage. 2. See Table 7 for details. DATA RETENTION MODE With valid VCC applied, the M48T129Y/V operates as a conventional BYTEWIDE static RAM. Should the supply voltage decay, the RAM will automatically deselect, write protecting itself when VCC falls between VPFD (max), VPFD (min) window. All outputs become high impedance and all inputs are treated as ”don’t care”. Note: A power failure during a write cycle may corrupt data at the current addressed location, but does not jeopardize the rest of the RAM’s content. At voltages below VPFD (min), the memory will be in a write protected state, provided the VCC fall time is not less than tF. The M48T129Y/V may respond to transient noise spikes on VCC that cross into the deselect window during the time the device is sampling VCC. Therefore, decoupling of the power supply lines is recommended. When VCC drops below VSO, the control circuit switches power to the internal battery, preserving data and powering the clock. The internal energy source will maintain data in the M48T129Y/V for an accumulated period of at least 10 years at room temperature. As system power rises above VSO, the battery is disconnected, and the power supply is switched to external VCC. Deselect continues for tREC after VCC reaches VPFD (max). For a further more detailed review of lifetime calculations, please see Application Note AN1012. TIMEKEEPER REGISTERS The M48T129Y/V offers 16 internal registers which contain TIMEKEEPER, Alarm, Watchdog, Interrupt, Flag, and Control data. These registers are memory locations which contain external (user accessible) and internal copies of the data (usually referred to as BiPORT TIMEKEEPER cells). The Table 4. AC Measurement Conditions ≤ 5ns Input Rise and Fall Times Input Pulse Voltages 0 to 3V Input and Output Timing Ref. Voltages 1.5V Note that Output Hi-Z is defined as the point where data is no longer driven. Figure 5. AC Testing Load Circuit 650Ω DEVICE UNDER TEST CL = 100pF CL includes JIG capacitance 1.75V AI01803C Note: Excluding open drain output pins external copies are independent of internal functions except that they are updated periodically by the simultaneous transfer of the incremented internal copy. TIMEKEEPER and Alarm Registers store data in BCD. 5/22 M48T129Y, M48T129V CLOCK OPERATIONS Reading the Clock Updates to the TIMEKEEPER registers should be halted before clock data is read to prevent reading data in transition. Because the BiPORT TIMEKEEPER cells in the RAM array are only data registers, and not the actual clock counters, updating the registers can be halted without disturbing the clock itself. Updating is halted when a ’1’ is written to the READ bit, D6 in the Control Register (1FFF8h). As long as a ’1’ remains in that position, updating is halted. After a halt is issued, the registers reflect the count; that is, the day, date, and time that were current at the moment the halt command was issued. All of the TIMEKEEPER registers are updated simultaneously. A halt will not interrupt an update in progress. Updating occurs 1 second after the READ bit is reset to a ’0’. Setting the Clock Bit D7 of the Control Register (1FFF8h) is the WRITE bit. Setting the WRITE bit to a ’1’, like the READ bit, halts updates to the TIMEKEEPER registers. The user can then load them with the correct day, date, and time data in 24 hour BCD format (see Table 11). Resetting the WRITE bit to a ’0’ then transfers the values of all time registers (1FFFFh-1FFF9h, 1FFF1h) to the actual TIMEKEEPER counters and allows normal operation to resume. After the WRITE bit is reset, the next clock update will occur approximately one second later. Note: Upon power-up following a power failure, both the WRITE bit and the READ bit will be reset to ’0’. Stopping and Starting the Oscillator The oscillator may be stopped at any time. If the device is going to spend a significant amount of time on the shelf, the oscillator can be turned off to minimize current drain on the battery. The STOP bit is located at Bit D7 within 1FFF9h. Setting it to 6/22 a ’1’ stops the oscillator. When reset to a ’0’, the M48T129Y/V oscillator starts within one second. Note: It is not necessary to set the WRITE bit when setting or resetting the FREQUENCY TEST bit (FT) or the STOP bit (ST). SETTING ALARM CLOCK Registers 1FFF6h-1FFF2h contain the alarm settings. The alarm can be configured to go off at a prescribed time on a specific month, date, hour, minute, or second or repeat every month, day, hour, minute, or second. It can also be programmed to go off while the M48T129Y/V is in the battery back-up to serve as a system wake-up call. Bits RPT5-RPT1 put the alarm in the repeat mode of operation. Table 12 shows the possible configurations. Codes not listed in the table default to the once per second mode to quickly alert the user of an incorrect alarm setting. Note: User must transition address (or toggle Chip Enable) to see Flag Bit change. When the clock information matches the alarm clock settings based on the match criteria defined by RPT5-RPT1, the AF (Alarm Flag) is set. If AFE (Alarm Flag Enable) is also set, the alarm condition activates the IRQ/FT pin. To disable alarm, write ’0’ to the Alarm Date register and RPT1-4. The IRQ/FT output is cleared by a read to the Flags register as shown in Figure 12. A subsequent read of the Flags register will reset the Alarm Flag (D6; Register 1FFF0h). The IRQ/FT pin can also be activated in the battery back-up mode. The IRQ/FT will go low if an alarm occurs and both ABE (Alarm in Battery Back-up Mode Enable) and AFE are set. The ABE and AFE bits are reset during power-up, therefore an alarm generated during power-up will only set AF. The user can read the Flag Register at system boot-up to determine if an alarm was generated while the M48T129Y/V was in the deselect mode during power-up. Figure 13 illustrates the back-up mode alarm timing. M48T129Y, M48T129V Table 5. Capacitance (1) (TA = 25 °C, f = MHz) Symbol C IN CIO (2) Parameter Input Capacitance Input / Output Capacitance Test Condit ion Min Max Unit VIN = 0V 20 pF VOUT = 0V 20 pF Note: 1. Effective capacitance measured with power supply at 5V (M48T129Y) or 3.3V (M48T129V). Sampled only, not 100% tested. 2. Outputs deselected. Table 6A. DC Characteristics (TA = 0 to 70 °C; VCC = 4.5V to 5.5V) Symbol Parameter ILI (1) Input Leakage Current ILO (1) Output Leakage Current Test Conditio n Min Max Unit 0V ≤ VIN ≤ V CC ±2 µA 0V ≤ VOUT ≤ VCC ±2 µA Outputs open 95 mA E = VIH 8 mA E = VCC –0.2V 4 mA ICC Supply Current ICC1 Supply Current (Standby) TTL ICC2 Supply Current (Standby) CMOS VIL Input Low Voltage –0.3 0.8 V VIH Input High Voltage 2.2 VCC + 0.3 V VOL Output Low Voltage I OL = 2.1mA 0.4 V VOH Output High Voltage IOH = –1mA 2.4 Test Conditio n Min V Note: 1. Outputs deselected. Table 6B. DC Characteristics (TA = 0 to 70 °C; VCC = 3.0V to 3.6V) Symbol Parameter ILI (1) Input Leakage Current ILO (1) Output Leakage Current Max Unit 0V ≤ VIN ≤ V CC ±2 µA 0V ≤ VOUT ≤ VCC ±2 µA Outputs open 50 mA E = VIH 4 mA E = VCC –0.2V 3 mA ICC Supply Current ICC1 Supply Current (Standby) TTL ICC2 Supply Current (Standby) CMOS VIL Input Low Voltage –0.3 0.4 V VIH Input High Voltage 2.2 VCC + 0.3 V VOL Output Low Voltage I OL = 2.1mA 0.4 V VOH Output High Voltage IOH = –1mA 2.2 V Note: 1. Outputs deselected. 7/22 M48T129Y, M48T129V Figure 6. Power Down/Up Mode AC Waveforms VCC VPFD (max) VPFD (min) VSO tF tR tFB INPUTS tRB tREC DON’T CARE RECOGNIZED RECOGNIZED HIGH-Z OUTPUTS VALID VALID RST AI01805 Table 7. Power Down/Up Trip Points DC Characteristics (1) (TA = 0 to 70 °C) Symbol Parameter VPFD Power-fail Deselect Voltage VSO Battery Back-up Switchover Voltage tDR (2) Min Typ Max Unit M48T129Y 4.2 4.35 4.5 V M48T129V 2.7 2.9 3.0 V M48T129Y 3.0 V M48T129V V PFD –100mV V Expected Data Retention Time 10 YEARS Note: 1. All voltages referenced to VSS. 2. At 25°C. Table 8. Power Down/Up AC Characteristics (TA = 0 to 70 °C) Symbol Parameter tF (1) VPFD (max) to VPFD (min) VCC Fall Time tFB (2) VPFD (min) to V SS VCC Fall Time Min Max Unit 300 µs M48T129Y 10 µs M48T129V 150 µs tR VPFD (min) to V PFD (max) VCC Rise Time 10 µs tRB VSS to VPFD (min) VCC Rise Time 1 µs tREC VPFD (max) to RST High 40 200 ms Note: 1. VPFD (max) to VPFD (min) fall time of less than tF may result in deselection/write protection not occurring until 50µs after VCC passes VPFD (min). 2. VPFD (min) to VSS fall time of less than tFB may cause corruption of RAM data. 8/22 M48T129Y, M48T129V Table 9. Read Mode AC Characteristics (TA = 0 to 70 °C) Symbol M48T129Y M48T129V -70 -85 Parameter Min tAVAV Read Cycle Time Max 70 Min Unit Max 85 ns tAVQV (1) Address Valid to Output Valid 70 85 ns tELQV (1) Chip Enable Low to Output Valid 70 85 ns tGLQV (1) Output Enable Low to Output Valid 40 55 ns tELQX (2) Chip Enable Low to Output Transition 5 5 ns tGLQX (2) Output Enable Low to Output Transition 5 5 ns tEHQZ (2) Chip Enable High to Output Hi-Z 25 30 ns tGHQZ (2) Output Enable High to Output Hi-Z 25 30 ns tAXQX (1) Address Transition to Output Transition 5 5 ns Note: 1. CL = 100pF. 2. CL = 5pF. Figure 7. Address Controlled, Read Mode AC Waveforms tAVAV A0-A16 VALID tAVQV tAXQX DQ0-DQ7 DATA VALID DATA VALID AI02324 9/22 M48T129Y, M48T129V Table 10. Write Mode AC Characteristics (TA = 0 to 70 °C) Symbol M48T129Y M48T129V -70 -85 Parameter Min Max Min Unit Max tAVAV Write Cycle Time 70 85 ns tAVWL Address Valid to Write Enable Low 0 0 ns tAVEL Address Valid to Chip Enable Low 0 0 ns tWLWH Write Enable Pulse Width 50 60 ns tELEH Chip Enable Low to Chip Enable High 55 65 ns tWHAX Write Enable High to Address Transition 5 5 ns t EHAX Chip Enable High to Address Transition 10 15 ns tDVWH Input Valid to Write Enable High 30 35 ns tDVEH Input Valid to Chip Enable High 30 35 ns tWHDX Write Enable High to Input Transition 5 5 ns tEHDX Chip Enable High to Input Transition 10 15 ns tWLQZ (1, 2) Write Enable Low to Output Hi-Z 25 30 ns tAVWH Address Valid to Write Enable High 60 70 ns tAVEH Address Valid to Chip Enable High 60 70 ns 5 5 ns tWHQX (1, 2) Write Enable High to Output Transition Note: 1. CL = 5pF. 2. If E goes low simultaneously with W going low, the outputs remain in the high impedance state. WATCHDOG TIMER The watchdog timer can be used to detect an outof-control microprocessor. The user programs the watchdog timer by setting the desired amount of time-out into the Watchdog Register, address 1FFF7h. Bits BMB4-BMB0 store a binary multiplier and the two lower order bits RB1-RB0 select the resolution, where 00 = 1/16 second, 01 = 1/4 second, 10 = 1 second, and 11 = 4 seconds. The amount of time-out is then determined to be the multiplication of the five bit multiplier value with the resolution. (For example: writing 00001110 in the Watchdog Register = 3*1 or 3 seconds). Note: Accuracy of timer is within ± the selected resolution. If the processor does not reset the timer within the specified period, the M48T129Y/V sets the WDF (Watchdog Flag) and generates a watchdog interrupt or a microprocessor reset. WDF is reset by reading the Flags Register (Address 1FFF0h). The most significant bit of the Watchdog Register is the Watchdog Steering Bit (WDS). When set to a ’0’, 10/22 the watchdog will activate the IRQ/FT pin when timed-out. When WDS is set to a ’1’, the watchdog will output a negative pulse on the RST pin for 40 to 200 ms. The Watchdog register and the FT bit will reset to a ’0’ at the end of a Watchdog time-out when the WDS bit is set to a ’1’. The watchdog timer can be reset by having the original time-out period re-written into the Watchdog Register, effectively restarting the count-down cycle. Should the watchdog timer time-out, and the WDS bit is programmed to output an interrupt, a value of 00h needs to be written to the Watchdog Register in order to clear the IRQ/FT pin. This will also disable the watchdog function until it is again programmed correctly. A read of the Flags Register will reset the Watchdog Flag (Bit D7; Register 1FFF0h). The watchdog function is automatically disabled upon power-down and the Watchdog Register is cleared. If the watchdog function is set to output to the IRQ/FT pin and the frequency test function is activated, the watchdog or alarm function prevails and the frequency test function is denied. M48T129Y, M48T129V Figure 8. Chip Enable or Output Enable Controlled, Read Mode AC Waveforms tAVAV A0-A16 VALID tAVQV tAXQX tELQV tEHQZ E tELQX tGLQV tGHQZ G tGLQX DQ0-DQ7 DATA OUT AI01197 Figure 9. Write Enable Controlled, Write AC Waveforms tAVAV A0-A16 VALID tAVWH tWHAX tAVEL E tWLWH tAVWL W tWLQZ tWHQX tWHDX DQ0-DQ7 DATA INPUT tDVWH AI02382 11/22 M48T129Y, M48T129V Figure 10. Chip Enable Controlled, Write AC Waveforms tAVAV A0-A16 VALID tAVEL tELEH tEHAX E tAVWL W tWHDX DQ0-DQ7 DATA INPUT tDVWH AI02582 POWER-ON RESET The M48T129Y/V continuously monitors VCC. When VCC falls to the power fail detect trip point, the RST pulls low (open drain) and remains low on power-up for 40 to 200ms after VCC passes VPFD. The RST pin is an open drain output and an appropriate pull-up resistor to VCC should be chosen to control the rise time. CALIBRATING THE CLOCK The M48T129Y/V is driven by a quartz controlled oscillator with a nominal frequency of 32,768Hz. The devices are factory calibrated at 25°C and tested for accuracy. Clock accuracy will not exceed 35 ppm (parts per million) oscillator frequency error at 25°C, which equates to about * 1.53 minutes per month. When the Calibration circuit is properly employed, accuracy improves to better than +4 ppm at 25°C. The oscillation rate of crystals changes with temperature. The M48T129Y/V design employs periodic counter correction. The calibration circuit adds or subtracts counts from the oscillator divider circuit at the divide by 256 stage, as shown in Figure 11. The number of times pulses which are blanked (subtracted, negative calibration) or split (added, positive calibration) depends upon the value loaded into the five Calibration bits found in the Control Register. Adding counts speeds the clock up, subtracting counts slows the clock down.The Calibra- 12/22 tion bits occupy the five lower order bits (D4-D0) in the Control Register 1FFF8h. These bits can be set to represent any value between 0 and 31 in binary form. Bit D5 is a Sign bit; ’1’ indicates positive calibration, ’0’ indicates negative calibration. Calibration occurs within a 64 minute cycle. The first 62 minutes in the cycle may, once per minute, have one second either shortened by 128 or lengthened by 256 oscillator cycles. If a binary ’1’ is loaded into the register, only the first 2 minutes in the 64 minute cycle will be modified; if a binary 6 is loaded, the first 12 will be affected, and so on. Therefore, each calibration step has the effect of adding 512 or subtracting 256 oscillator cycles for every 125, 829, 120 actual oscillator cycles, that is +4.068 or –2.034 ppm of adjustment per calibration step in the calibration register. Assuming that the oscillator is running at exactly 32,768Hz, each of the 31 increments in the Calibration byte would represent +10.7 or –5.35 seconds per month which corresponds to a total range of +5.5 or –2.75 minutes per month. Figure 11 illustrates a TIMEKEEPER calibration waveform. Two methods are available for ascertaining how much calibration a given M48T129Y/V may require. The first involves setting the clock, letting it run for a month and comparing it to a known accurate reference and recording deviation over a fixed period of time. M48T129Y, M48T129V Table 11. TIMEKEEPER Register Map Data Address D7 D6 1FFFFh D5 D4 D3 D2 10 Years D0 Function/Rang e BCD Format Year Year 00-99 Month Month 01-12 Date Date 01-31 Day of Week Day 01-07 Hours (24 Hours Format) Hour 00-23 1FFFEh 0 0 1FFFDh 0 0 1FFFCh 0 FT 1FFFBh 0 0 1FFFAh 0 10 Minutes Minutes Minutes 00-59 1FFF9h ST 10 Seconds Seconds Seconds 00-59 1FFF8h W R S 1FFF7h WDS BMB4 BMB3 BMB2 1FFF6h AFE 0 ABE Al 10M 1FFF5h RPT4 RPT5 1FFF4h RPT3 0 1FFF3h RPT2 1FFF2h RPT1 1FFF1h 1FFF0h Keys: 0 D1 10 M. 10 Date 0 0 0 10 Hours Calibration BMB1 RB1 RB0 Watchdog Alarm Month A Month 01-12 Al 10 Date Alarm Date A Date 01-31 Al 10 Hours Alarm Hours A Hours 00-23 Alarm 10 Minutes Alarm Minutes A Minutes 00-59 Alarm 10 Seconds Alarm Seconds A Seconds 00-59 100 Year Century 00-99 1000 Year WDF BMB0 Control AF 0 S = SIGN Bit FT = FREQUENCY TEST Bit R = READ Bit W = WRITE Bit ST = STOP Bit 0 = Must be set to zero Y = ’1’ or ’0’ BL = Battery Low BL Y Y Y Y Flags AF = Alarm Flag WDS = Watchdog Steering Bit BMB0-BMB4 = Watchdog Multiplier Bits RB0-RB1 = Watchdog Resolution Bits AFE = Alarm Flag Enable ABE = Alarm in Battery Back-up Mode Enable RPT1-RPT5 = Alarm Repeat Mode Bits WDF = Watchdog Flag Figure 11. Calibration Waveform NORMAL POSITIVE CALIBRATION NEGATIVE CALIBRATION AI00594B 13/22 M48T129Y, M48T129V Figure 12. Alarm Interrupt Reset Waveform 15ns Min ADDRESS 1FF0h AD0-AD7 ACTIVE FLAG BIT IRQ/FT HIGH-Z AI02581 Figure 13. Back-up Mode Alarm Waveforms tREC VCC VPFD (max) VPFD (min) VSO AFE bit in Interrupt Register AF bit in Flags Register IRQ/FT HIGH-Z HIGH-Z AI01678C Calibration values, including the number of seconds lost or gained in a given period, can be found in Application Note: TIMEKEEPER CALIBRATION. This allows the designer to give the end user the ability to calibrate the clock as the environment requires, even if the final product is packaged in a non-user serviceable enclosure. The designer could provide a simple utility that accesses the Calibration byte. The second approach is better suited to a manufacturing environment, and involves the use of the IRQ/FT pin. The pin will toggle at 512Hz, when the Stop bit (ST, D7 of 1FFF9h) is ’0’,the Frequency Test bit (FT, D6 of 1FFFCh) is ’1’, the Alarm Flag 14/22 Enable bit (AFE, D7 of 1FFF6h) is ’0’, and the Watchdog Steering bit (WDS, D7 of 1FFF7h) is ’1’ or the Watchdog Register (1FFF7h=0) is reset. Note: A 4 second settling time must be allowed before reading the 512Hz output. Any deviation from 512Hz indicates the degree and direction of oscillator frequency shift at the test temperature. For example, a reading of 512.010124Hz would indicate a +20 ppm oscillator frequency error, requiring a –10 (WR001010) to be loaded into the Calibration Byte for correction. Note that setting or changing the Calibration Byte does not affect the Frequency test output frequency. M48T129Y, M48T129V Table 12. Alarm Repeat Modes RPT4 RPT3 RPT2 RPT1 1 1 1 1 Once per Second 1 1 1 0 Once per Minute 1 1 0 0 Once per Hour 1 0 0 0 Once per Day 1 0 0 0 Once per Month Figure 14. Supply Voltage Protection VCC VCC 0.1µF DEVICE VSS AI02169 The IRQ/FT pin is an open drain output which requires a pull-up resistor to VCC for proper operation. A 500-10k resistor is recommended in order to control the rise time. The FT bit is cleared on power-up. BATTERY LOW WARNING The M48T129Y/V automatically performs battery voltage monitoring upon power-up and at factoryprogrammed time intervals of approximately 24 hours. The Battery Low (BL) bit, Bit D4 of Flags Register 1FFF0h, will be asserted if the battery voltage is found to be less than approximately 2.5V. If a battery low is generated during a power-up sequence, this indicates that the battery is below approximately 2.5 volts and may not be able to maintain data integrity in the SRAM. Data should be considered suspect and verified as correct. Alarm Activated If a battery low indication is generated during the 24-hour interval check, this indicates that the battery is near end of life. However, data is not compromised due to the fact that a nominal VCC is supplied. The M48T129Y/V only monitors the battery when a nominal VCC is applied to the device. Thus applications which require extensive durations in the battery back-up mode should be powered-up periodically (at least once every few months) in order for this technique to be beneficial. Additionally, if a battery low is indicated, data integrity should be verified upon power-up via a checksum or other technique. POWER-ON DEFAULTS Upon application of power to the device, the following register bits are set to a ’0’ state: WDS, BMB0-BMB4, RB0,RB1, AFE, ABE, W, R and FT. POWER SUPPLY DECOUPLING and UNDERSHOOT PROTECTION ICC transients, including those produced by output switching, can produce voltage fluctuations, resulting in spikes on the VCC bus. These transients can be reduced if capacitors are used to store energy, which stabilizes the VCC bus. The energy stored in the bypass capacitors will be released as low going spikes are generated or energy will be absorbed when overshoots occur. A ceramic bypass capacitor value of 0.1µF (see Figure 14) is recommended in order to provide the needed filtering. In addition to transients that are caused by normal SRAM operation, power cycling can generate negative voltage spikes on VCC that drive it to values below V SS by as much as one volt. These negative spikes can cause data corruption in the SRAM while in battery backup mode. To protect from these voltage spikes, ST recommends connecting a schottky diode from VCC to VSS (cathode connected to VCC, anode to VSS). (Schottky diode 1N5817 is recommended for through hole and MBRS120T3 is recommended for surface mount). 15/22 M48T129Y, M48T129V Table 13. Ordering Information Scheme Example: M48T129Y -70 PM 1 Device Type M48T Supply Voltage and Write Protect Voltage 129Y = VCC = 4.5V to 5.5V; VPFD = 4.2V to 4.5V 129V = VCC = 3.0V to 3.6V; VPFD = 2.7V to 3.0V Speed -70 = 70ns -85 = 85ns Package PM = PMDIP32 CS (1) = Surface Mount Chip Set solution M48T201Y/V (SOH44) + M68Z128/W (TSOP32) Temperature Range 1 = 0 to 70 °C Note: 1. The SOIC package (SOH44) requires the battery package (SNAPHAT ) which is ordered separately under the part number ”M4Txx-BR12SH1” in plastic tube or ”M4Txx-BR12SH1TR” in Tape & Reel form. Caution: Do not place the SNAPHAT battery package ”M4Txx-BR12SH1” in conductive foam since this will drain the lithium button-cell battery. For a list of available options (Speed, Package, etc...) or for further information on any aspect of this device, please contact the ST Sales Office nearest to you. Table 14. Revision History Date April 2000 16/22 Revision Details Chipset datasheet - First Issue M48T129Y, M48T129V Table 15. PMDIP32 - 32 pin Plastic Module DIP, Package Mechanical Data mm inches Symb Typ Min Max A 9.27 A1 Typ Min Max 9.52 0.365 0.375 0.38 – 0.015 – B 0.43 0.59 0.017 0.023 C 0.20 0.33 0.008 0.013 D 42.42 43.18 1.670 1.700 E 18.03 18.80 0.710 0.740 e1 2.29 2.79 0.090 0.110 e3 34.29 41.91 1.350 1.650 eA 14.99 16.00 0.590 0.630 L 3.05 3.81 0.120 0.150 S 1.91 2.79 0.075 0.110 N 32 32 Figure 15. PMDIP32 - 32 pin Plastic Module DIP, Package Outline A A1 S B L C eA e1 e3 D N E 1 PMDIP Drawing is not to scale. 17/22 M48T129Y, M48T129V Table 16. TSOP32 - 32 lead Plastic Thin Small Outline, 8 x 20mm, Package Mechanical Data mm inch Symbol Typ Min Max A Typ Min 1.200 0.0472 A1 0.050 0.150 0.0020 0.0059 A2 0.950 1.050 0.0374 0.0413 B 0.150 0.270 0.0059 0.0106 C 0.100 0.210 0.0039 0.0083 D 19.800 20.200 0.7795 0.7953 D1 18.300 18.500 0.7205 0.7283 – – – – E 7.900 8.100 0.3110 0.3189 L 0.500 0.700 0.0197 0.0276 α 0° 5° 0° 5° e 0.500 CP 0.0197 0.100 N 32 0.0039 1.3 Figure 16. TSOP32 - 32 lead Plastic Thin Small Outline, 8 x 20mm, Package Outline A2 1 N e E B N/2 D1 A CP D DIE C TSOP-a Drawing is not to scale. 18/22 Max A1 α L M48T129Y, M48T129V Table 17. SH - 4-pin SNAPHAT Housing for 48 mAh Battery & Crystal, Package Mechanical Data mm inches Symb Typ Min A Max Typ Min Max 9.78 0.385 A1 6.73 7.24 0.265 0.285 A2 6.48 6.99 0.255 0.275 A3 0.38 0.015 B 0.46 0.56 0.018 0.022 D 21.21 21.84 0.835 0.860 E 14.22 14.99 0.560 0.590 eA 15.55 15.95 0.612 0.628 eB 3.20 3.61 0.126 0.142 L 2.03 2.29 0.080 0.090 Figure 17. SH - 4-pin SNAPHAT Housing for 48 mAh Battery & Crystal, Package Outline A1 eA A2 A A3 B L eB D E SHTK-A Drawing is not to scale. 19/22 M48T129Y, M48T129V Table 18. SH - 4-pin SNAPHAT Housing for 120 mAh Battery & Crystal, Package Mechanical Data mm inches Symb Typ Min A Max Typ Min Max 10.54 0.415 A1 8.00 8.51 0.315 .0335 A2 7.24 8.00 0.285 0.315 A3 0.38 0.015 B 0.46 0.56 0.018 0.022 D 21.21 21.84 0.835 0.860 E 17.27 18.03 0.680 .0710 eA 15.55 15.95 0.612 0.628 eB 3.20 3.61 0.126 0.142 L 2.03 2.29 0.080 0.090 Figure 18. SH - 4-pin SNAPHAT Housing for 120 mAh Battery & Crystal, Package Outline A1 eA A2 A A3 B L eB D E SHTK-A Drawing is not to scale. 20/22 M48T129Y, M48T129V Table 19. SOH44 - 44 lead Plastic Small Outline, 4-socket battery, SNAPHAT, Package Mechanical Data mm inches Symb Typ Min Max A Typ Min 3.05 Max 0.120 A1 0.05 0.36 0.002 0.014 A2 2.34 2.69 0.092 0.106 B 0.36 0.46 0.014 0.018 C 0.15 0.32 0.006 0.012 D 17.71 18.49 0.697 0.728 E 8.23 8.89 0.324 0.350 – – – – eB 3.20 3.61 0.126 0.142 H 11.51 12.70 0.453 0.500 L 0.41 1.27 0.016 0.050 α 0° 8° 0° 8° N 44 e 0.81 0.032 44 CP 0.10 0.004 Figure 19. SOH44 - 44 lead Plastic Small Outline, 4-socket battery, SNAPHAT, Package Outline A2 A C B eB e CP D N E H A1 α L 1 SOH-A Drawing is not to scale. 21/22 M48T129Y, M48T129V Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in lif e support devices or systems without express written approval of STMicroelectronics. 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