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M48T02 M48T12
5.0V, 16 Kbit (2Kb x 8) TIMEKEEPER(R) SRAM
Features

Integrated, ultra low power SRAM, real time clock, and power-fail control circuit BYTEWIDETM RAM-like clock access BCD coded year, month, day, date, hours, minutes, and seconds Typical clock accuracy of 1 minute a month, at 25C Software controlled clock calibration for high accuracy applications Automatic power-fail chip deselect and WRITE protection WRITE protect voltages (VPFD = Power-fail deselect voltage): - M48T02: VCC = 4.75 to 5.5V 4.5V VPFD 4.75V - M48T12: VCC = 4.5 to 5.5V 4.2V VPFD 4.5V Self-contained battery and crystal in the CAPHATTM DIP package Pin and function compatible with JEDEC standard 2K x8 SRAMs RoHS compliant - Lead-free second level interconnect
24 1

PCDIP24 (PC) battery/crystal CAPHATTM
September 2007
Rev 6
1/24
www.st.com 1
Contents
M48T02, M48T12
Contents
1 2 Summary description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Operation modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 2.2 2.3 Read mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Write mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Data retention mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3
Clock operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1 3.2 3.3 3.4 3.5 Reading the clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Setting the clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Stopping and starting the oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Calibrating the clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 VCC noise and negative going transients . . . . . . . . . . . . . . . . . . . . . . . . . 15
4 5 6 7 8
Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 DC and AC parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Part numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
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M48T02, M48T12
List of tables
List of tables
Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. Table 11. Table 12. Table 13. Table 14. Signal names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Operating modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Read mode AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Write mode AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Register map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Operating and AC measurement conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 DC characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Power down/up AC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Power down/up trip points DC characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 PCDIP24 - 24-pin plastic DIP, battery CAPHAT, package mechanical data . . . . . . . . . . . 21 Ordering information scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
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List of figures
M48T02, M48T12
List of figures
Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 DIP connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Read mode AC waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Write enable controlled, write AC waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Chip enable controlled, write AC waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Checking the BOK flag status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Crystal accuracy across temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Clock calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Supply voltage protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 AC testing load circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Power down/up mode AC waveforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 PCDIP24 - 24-pin plastic DIP, battery CAPHAT, package outline . . . . . . . . . . . . . . . . . . . 21
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M48T02, M48T12
Summary description
1
Summary description
The M48T02/12 TIMEKEEPER(R) RAM is a 2Kb x 8 non-volatile static RAM and real time clock which is pin and functional compatible with the DS1642. A special 24-pin, 600mil DIP CAPHATTM package houses the M48T02/12 silicon with a quartz crystal and a long life lithium button cell to form a highly integrated battery backed-up memory and real time clock solution. The M48T02/12 button cell has sufficient capacity and storage life to maintain data and clock functionality for an accumulated time period of at least 10 years in the absence of power over the operating temperature range. The M48T02/12 is a non-volatile pin and function equivalent to any JEDEC standard 2Kb x 8 SRAM. It also easily fits into many ROM, EPROM, and EEPROM sockets, providing the non-volatility of PROMs without any requirement for special WRITE timing or limitations on the number of WRITEs that can be performed. Figure 1. Logic diagram
VCC
11 A0-A10
8 DQ0-DQ7
W E G
M48T02 M48T12
VSS
AI01027
Table 1.
A0-A10 DQ0-DQ7 E G W VCC VSS
Signal names
Address Inputs Data Inputs / Outputs Chip Enable Output Enable WRITE Enable Supply Voltage Ground
5/24
Summary description Figure 2. DIP connections
A7 A6 A5 A4 A3 A2 A1 A0 DQ0 DQ1 DQ2 VSS 1 24 2 23 3 22 4 21 5 20 M48T02 19 6 M48T12 18 7 8 17 9 16 10 15 14 11 13 12
AI01028
M48T02, M48T12
VCC A8 A9 W G A10 E DQ7 DQ6 DQ5 DQ4 DQ3
Figure 3.
Block diagram
OSCILLATOR AND CLOCK CHAIN 32,768 Hz CRYSTAL POWER
8 x 8 BiPORT SRAM ARRAY
A0-A10
2040 x 8 SRAM ARRAY LITHIUM CELL VOLTAGE SENSE AND SWITCHING CIRCUITRY VPFD
DQ0-DQ7
E W
BOK
G
VCC
VSS
AI01329
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M48T02, M48T12
Operation modes
2
Operation modes
As Figure 3 on page 6 shows, the static memory array and the quartz controlled clock oscillator of the M48T02/12 are integrated on one silicon chip. The two circuits are interconnected at the upper eight memory locations to provide user accessible BYTEWIDETM clock information in the bytes with addresses 7F8h-7FFh. The clock locations contain the year, month, date, day, hour, minute, and second in 24 hour BCD format. Corrections for 28, 29 (leap year - valid until 2100), 30, and 31 day months are made automatically. Byte 7F8h is the clock control register. This byte controls user access to the clock information and also stores the clock calibration setting. The eight clock bytes are not the actual clock counters themselves; they are memory locations consisting of BiPORTTM READ/WRITE memory cells. The M48T02/12 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. The M48T02/12 also has its own Power-fail Detect circuit. The control circuitry constantly monitors the single 5V supply for an out of tolerance condition. When VCC is out of tolerance, the circuit write protects the SRAM, providing a high degree of data security in the midst of unpredictable system operation brought on by low VCC. As VCC falls below approximately 3V, the control circuitry connects the battery which maintains data and clock operation until valid power returns. Table 2.
Mode Deselect WRITE READ READ Deselect Deselect VSO to VPFD(min)(1) VSO(1) 4.75 to 5.5V or 4.5 to 5.5V
Operating modes
VCC E VIH VIL VIL VIL X X G X X VIL VIH X X W X VIL VIH VIH X X DQ0-DQ7 High Z DIN DOUT High Z High Z High Z Power Standby Active Active Active CMOS Standby Battery Back-up Mode
1. See Table 11 on page 20 for details.
Note:
X = VIH or VIL; VSO = Battery Back-up Switchover Voltage.
2.1
Read mode
The M48T02/12 is in the READ Mode whenever W (WRITE Enable) is high and E (Chip Enable) is low. The device architecture allows ripple-through access of data from eight of 16,384 locations in the static storage array. Thus, the unique address specified by the 11 Address Inputs defines which one of the 2,048 bytes of data is to be accessed. Valid data will be available at the Data I/O pins within Address Access time (tAVQV) after the last address input signal is stable, providing that 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 time (tELQV) or Output Enable Access time (tGLQV).
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Operation modes
M48T02, M48T12
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 Output Data Hold time (tAXQX) but will go indeterminate until the next Address Access. Figure 4. Read mode AC waveforms
tAVAV A0-A10 tAVQV tELQV E tELQX tGLQV G tGLQX DQ0-DQ7 VALID
AI01330
VALID tAXQX tEHQZ
tGHQZ
Note: Table 3.
WRITE Enable (W) = High. Read mode AC characteristics
M48T02/M48T12
Symbol
Parameter(1)
-70 Min Max
-150 Min 150 70 70 35 150 150 75 10 5 25 25 35 35 5 5 Max
-200 Min 200 200 200 80 10 5 40 40 Max
Unit
tAVAV tAVQV tELQV tGLQV tELQX tGLQX tEHQZ tGHQZ tAXQX
READ Cycle Time Address Valid to Output Valid Chip Enable Low to Output Valid Output Enable Low to Output Valid Chip Enable Low to Output Transition Output Enable Low to Output Transition Chip Enable High to Output Hi-Z Output Enable High to Output Hi-Z Address Transition to Output Transition
70
ns ns ns ns ns ns ns ns ns
5 5
10
1. Valid for Ambient Operating Temperature: TA = 0 to 70C; VCC = 4.75 to 5.5V or 4.5 to 5.5V (except where noted).
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M48T02, M48T12
Operation modes
2.2
Write mode
The M48T02/12 is in the WRITE Mode whenever W and E are active. 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 tWHDX 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.
Figure 5.
Write enable controlled, write AC waveform
tAVAV A0-A10 VALID tAVWH tAVEL E tWLWH tAVWL W tWLQZ tWHDX DQ0-DQ7 DATA INPUT tDVWH
AI01331
tWHAX
tWHQX
Figure 6.
Chip enable controlled, write AC waveforms
tAVAV A0-A10 VALID tAVEH tAVEL E tAVWL W tEHDX DQ0-DQ7 DATA INPUT tDVEH
AI01332B
tELEH
tEHAX
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Operation modes Table 4. Write mode AC characteristics
M48T02, M48T12
M48T02/M48T12 Symbol Parameter(1) -70 -150 -200 Unit
Min Max Min Max Min Max tAVAV tAVWL tAVEL tWLWH tELEH tWHAX tEHAX tDVWH tDVEH tWHDX tEHDX tWLQZ tAVWH tAVEH tWHQX WRITE Cycle Time Address Valid to WRITE Enable Low Address Valid to Chip Enable Low WRITE Enable Pulse Width Chip Enable Low to Chip Enable High WRITE Enable High to Address Transition Chip Enable High to Address Transition Input Valid to WRITE Enable High Input Valid to Chip Enable High WRITE Enable High to Input Transition Chip Enable High to Input Transition WRITE Enable Low to Output Hi-Z Address Valid to WRITE Enable High Address Valid to Chip Enable High WRITE Enable High to Output Transition 60 60 5 70 0 0 50 55 0 0 30 30 5 5 25 120 120 10 150 0 0 90 90 10 10 40 40 5 5 50 140 140 10 200 0 0 120 120 10 10 60 60 5 5 60 ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns
1. Valid for Ambient Operating Temperature: TA = 0 to 70C; VCC = 4.75 to 5.5V or 4.5 to 5.5V (except where noted).
2.3
Data retention mode
With valid VCC applied, the M48T02/12 operates as a conventional BYTEWIDETM static RAM. Should the supply voltage decay, the RAM will automatically power-fail deselect, write protecting itself when VCC falls within the 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 currently addressed location, but does not jeopardize the rest of the RAM's content. At voltages below VPFD (min), the user can be assured the memory will be in a write protected state, provided the VCC fall time is not less than tF. The M48T02/12 may respond to transient noise spikes on VCC that reach into the deselect window during the time the device is sampling VCC. Therefore, decoupling of the power supply lines is recommended. The power switching circuit connects external VCC to the RAM and disconnects the battery when VCC rises above VSO. As VCC rises, the battery voltage is checked. If the voltage is too low, an internal Battery Not OK (BOK) flag will be set. The BOK flag can be checked after power up. If the BOK flag is set, the first WRITE attempted will be blocked. The flag is automatically cleared after the first WRITE, and normal RAM operation resumes. Figure 7 on page 11 illustrates how a BOK check routine could be structured. For more information on a Battery Storage Life refer to the Application Note AN1012.
10/24
M48T02, M48T12 Figure 7. Checking the BOK flag status
POWER-UP
Operation modes
READ DATA AT ANY ADDRESS
WRITE DATA COMPLEMENT BACK TO SAME ADDRESS
READ DATA AT SAME ADDRESS AGAIN
IS DATA COMPLEMENT OF FIRST READ? (BATTERY OK) YES
NO (BATTERY LOW)
NOTIFY SYSTEM OF LOW BATTERY (DATA MAY BE CORRUPTED)
WRITE ORIGINAL DATA BACK TO SAME ADDRESS
CONTINUE
AI00607
11/24
Clock operations
M48T02, M48T12
3
3.1
Clock operations
Reading the clock
Updates to the TIMEKEEPER(R) registers should be halted before clock data is read to prevent reading data in transition. The BiPORTTM TIMEKEEPER cells in the RAM array are only data registers and not the actual clock counters, so updating the registers can be halted without disturbing the clock itself. Updating is halted when a '1' is written to the READ Bit, the seventh bit in the control register. 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 the 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 is within a second after the bit is reset to a '0.'
3.2
Setting the clock
The eighth bit of the control register 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 (on Table 5 on page 13). Resetting the WRITE Bit to a '0' then transfers the values of all time registers (7F9-7FF) to the actual TIMEKEEPER counters and allows normal operation to resume. The FT Bit and the bits marked as '0' in Table 5 on page 13 must be written to '0' to allow for normal TIMEKEEPER and RAM operation. See the Application Note AN923, "TIMEKEEPER(R) Rolling Into the 21st Century" for information on Century Rollover.
12/24
M48T02, M48T12 Table 5.
Addres s 7FF 7FE 7FD 7FC 7FB 7FA 7F9 7F8 0 0 0 0 0 ST W R
Clock operations Register map
Data D7 D6 D5 D4 D3 D2 D1 Year 10 M Month Date 0 Day Hours Minutes Seconds Calibration D0 Function/Range BCD Format Year Month Date Day Hours Minutes Seconds Control 00-99 01-12 01-31 01-07 00-23 00-59 00-59
10 Years 0 0 FT 0 0
10 Date 0 0
10 Hours 10 Minutes 10 Seconds S
Keys: S = SIGN Bit FT = FREQUENCY TEST Bit (Set to '0' for normal clock operation) R = READ Bit W = WRITE Bit ST = STOP Bit 0 = Must be set to '0'
3.3
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 the MSB of the seconds register. Setting it to a '1' stops the oscillator. The M48T02/12 is shipped from STMicroelectronics with the STOP Bit set to a '1.' When reset to a '0,' the M48T02/12 oscillator starts within one second.
3.4
Calibrating the clock
The M48T02/12 is driven by a quartz-controlled oscillator with a nominal frequency of 32,768 Hz. A typical M48T02/12 is accurate within 1 minute per month at 25C without calibration. The devices are tested not to exceed 35 ppm (parts per million) oscillator frequency error at 25C, which equates to about 1.53 minutes per month. The oscillation rate of any crystal changes with temperature. Figure 8 on page 15 shows the frequency error that can be expected at various temperatures. Most clock chips compensate for crystal frequency and temperature shift error with cumbersome "trim" capacitors. The M48T02/12 design, however, 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 9 on page 15. The number of times pulses are blanked (subtracted, negative calibration) or split (added, positive calibration) depends upon the value loaded into the five-bit Calibration Byte found in the Control Register. Adding counts speeds the clock up, subtracting counts slows the clock down. The Calibration Byte occupies the five lower order bits in the Control register. This byte can be set to represent any value between 0 and 31 in binary form. The sixth bit is the Sign Bit;
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Clock operations
M48T02, M48T12
'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 in fact 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. Two methods are available for ascertaining how much calibration a given M48T02/12 may require. The first involves simply setting the clock, letting it run for a month and comparing it to a known accurate reference (like WWV broadcasts). While that may seem crude, it allows the designer to give the end user the ability to calibrate his clock as his environment may require, even after the final product is packaged in a non-user serviceable enclosure. All the designer has to do is provide a simple utility that accesses the Calibration Byte. The second approach is better suited to a manufacturing environment, and involves the use of some test equipment. When the Frequency Test (FT) Bit, the seventh-most significant bit in the Day Register, is set to a '1,' and the oscillator is running at 32,768 Hz, the LSB (DQ0) of the Seconds Register will toggle at 512 Hz. Any deviation from 512 Hz indicates the degree and direction of oscillator frequency shift at the test temperature. For example, a reading of 512.01024 Hz would indicate a +20 ppm oscillator frequency error, requiring a - 10 (WR001010) to be loaded into the Calibration Byte for correction. Note: Setting or changing the Calibration Byte does not affect the Frequency Test output frequency. The device must be selected and addresses must be stable at Address 7F9 when reading the 512 Hz on DQ0. The FT Bit must be set using the same method used to set the clock: using the WRITE Bit. The LSB of the Seconds Register is monitored by holding the M48T02/12 in an extended READ of the Seconds Register, but without having the READ Bit set. The FT Bit MUST be reset to '0' for normal clock operations to resume. Note: It is not necessary to set the WRITE Bit when setting or resetting the Frequency Test Bit (FT) or the Stop Bit (ST). For more information on calibration, see the Application Note AN924, "TIMEKEEPER(R) Calibration."
14/24
M48T02, M48T12 Figure 8. Crystal accuracy across temperature
ppm 20
Clock operations
0
-20
-40 F = -0.038 ppm (T - T )2 10% 0 F C2 T0 = 25 C -80
-60
-100 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 C
AI02124
Figure 9.
Clock calibration
NORMAL
POSITIVE CALIBRATION
NEGATIVE CALIBRATION
AI00594B
3.5
VCC noise and negative going transients
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 0.1F (as shown in Figure 10 on page 16) 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 VSS 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, it is recommended to connect a
15/24
Clock operations
M48T02, M48T12
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. Figure 10. Supply voltage protection
VCC VCC
0.1F
DEVICE
VSS
AI02169
16/24
M48T02, M48T12
Maximum rating
4
Maximum rating
Stressing the device above the rating listed in the "Absolute Maximum Ratings" table may cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other conditions above those indicated in the Operating sections of this specification is not implied. Exposure to Absolute Maximum Rating conditions for extended periods may affect device reliability. Refer also to the STMicroelectronics SURE Program and other relevant quality documents. Table 6.
Symbol TA TSTG TSLD(1) VIO VCC IO PD
Absolute maximum ratings
Parameter Ambient Operating Temperature Storage Temperature (VCC Off, Oscillator Off) Lead Solder Temperature for 10 seconds Input or Output Voltages Supply Voltage Output Current Power Dissipation Value 0 to 70 -40 to 85 260 -0.3 to 7 -0.3 to 7 20 1 Unit C C C V V mA W
1. Soldering temperature not to exceed 260C for 10 seconds (total thermal budget not to exceed 150C for longer than 30 seconds).
Caution:
Negative undershoots below -0.3V are not allowed on any pin while in the Battery Back-up mode.
17/24
DC and AC parameters
M48T02, M48T12
5
DC and AC parameters
This section summarizes the operating and measurement conditions, as well as the DC and AC characteristics of the device. The parameters in the following DC and AC Characteristic tables are derived from tests performed under the Measurement Conditions listed in the relevant tables. Designers should check that the operating conditions in their projects match the measurement conditions when using the quoted parameters. Table 7. Operating and AC measurement conditions
Parameter Supply Voltage (VCC) Ambient Operating Temperature (TA) Load Capacitance (CL) Input Rise and Fall Times Input Pulse Voltages Input and Output Timing Ref. Voltages M48T02 4.75 to 5.5 0 to 70 100 5 0 to 3 1.5 M48T12 4.5 to 5.5 0 to 70 100 5 0 to 3 1.5 Unit V C pF ns V V
Note:
Output Hi-Z is defined as the point where data is no longer driven. Figure 11. AC testing load circuit
5V
1.8k DEVICE UNDER TEST 1k
OUT
CL = 100pF
CL includes JIG capacitance
AI01019
Table 8.
Symbol CIN CIO
(3)
Capacitance
Parameter(1)(2) Input Capacitance Input / Output Capacitance Min Max 10 10 Unit pF pF
1. Effective capacitance measured with power supply at 5V. Sampled only, not 100% tested. 2. At 25C, f = 1MHz. 3. Outputs deselected.
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M48T02, M48T12 Table 9.
Symbol ILI ILO(2) ICC ICC1(3) ICC2
(3)
DC and AC parameters
DC characteristics
Parameter Input Leakage Current Output Leakage Current Supply Current Supply Current (Standby) TTL Supply Current (Standby) CMOS Input Low Voltage Input High Voltage Output Low Voltage Output High Voltage IOL = 2.1mA IOH = -1mA 2.4 Test condition(1) 0V VIN VCC 0V VOUT VCC Outputs open E = VIH E = VCC - 0.2V -0.3 2.2 Min Max 1 1 80 3 3 0.8 VCC + 0.3 0.4 Unit A A mA mA mA V V V V
VIL VIH VOL VOH
1. Valid for Ambient Operating Temperature: TA = 0 to 70C; VCC = 4.75 to 5.5V or 4.5 to 5.5V (except where noted). 2. Outputs deselected. 3. Measured with Control Bits set as follows: R = '1'; W, ST, FT = '0.'
Figure 12. Power down/up mode AC waveforms
VCC VPFD (max) VPFD (min) VSO tF tPD INPUTS
RECOGNIZED
tDR tFB tRB DON'T CARE
tR trec
NOTE RECOGNIZED
HIGH-Z OUTPUTS VALID
(PER CONTROL INPUT)
VALID
(PER CONTROL INPUT)
AI00606
Note:
Inputs may or may not be recognized at this time. Caution should be taken to keep E high as VCC rises past VPFD (min). Some systems may perform inadvertent WRITE cycles after VCC rises above VPFD (min) but before normal system operations begin. Even though a power on reset is being applied to the processor, a reset condition may not occur until after the system clock is running.
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DC and AC parameters Table 10.
Symbol tPD tF(2) tFB(3) tR tRB trec
M48T02, M48T12 Power down/up AC characteristics
Parameter(1) E or W at VIH before Power Down VPFD (max) to VPFD (min) VCC Fall Time VPFD (min) to VSS VCC Fall Time VPFD (min) to VPFD (max) VCC Rise Time VSS to VPFD (min) VCC Rise Time E or W at VIH before Power Up Min 0 300 10 0 1 2 Max Unit s s s s s ms
1. Valid for Ambient Operating Temperature: TA = 0 to 70C; VCC = 4.75 to 5.5V or 4.5 to 5.5V (except where noted). 2. VPFD (max) to VPFD (min) fall time of less than tF may result in deselection/write protection not occurring until 200s after VCC passes VPFD (min). 3. VPFD (min) to VSS fall time of less than tFB may cause corruption of RAM data.
Table 11.
Symbol VPFD VSO tDR
(3)
Power down/up trip points DC characteristics
Parameter(1)(2) Power-fail Deselect Voltage M48T02 M48T12 Min 4.5 4.2 Typ 4.6 4.3 3.0 10 Max 4.75 4.5 Unit V V V YEARS
Battery Back-up Switchover Voltage Expected Data Retention Time
1. All voltages referenced to VSS. 2. Valid for Ambient Operating Temperature: TA = 0 to 70C; VCC = 4.75 to 5.5V or 4.5 to 5.5V (except where noted). 3. At 25C; VCC = 0V.
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M48T02, M48T12
Package mechanical data
6
Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK(R) packages. These packages have a Lead-free second level interconnect. The category of second Level Interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com. Figure 13. PCDIP24 - 24-pin plastic DIP, battery CAPHAT, package outline
A2
A
A1 B1 B e3 D
N
L eA
C
e1
E
1 PCDIP
Note:
Drawing is not to scale. Table 12.
Symb Typ A A1 A2 B B1 C D E e1 e3 eA L N Min 8.89 0.38 8.38 0.38 1.14 0.20 34.29 17.83 2.29 25.15 15.24 3.05 24 Max 9.65 0.76 8.89 0.53 1.78 0.31 34.80 18.34 2.79 30.73 16.00 3.81 Typ Min 0.350 0.015 0.330 0.015 0.045 0.008 1.350 0.702 0.090 0.990 0.600 0.120 24 Max 0.380 0.030 0.350 0.021 0.070 0.012 1.370 0.722 0.110 1.210 0.630 0.150
PCDIP24 - 24-pin plastic DIP, battery CAPHAT, package mechanical data
mm inches
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Part numbering
M48T02, M48T12
7
Part numbering
Table 13.
Example:
Ordering information scheme
M48T 02 -70 PC 1
Device type M48T
Supply voltage and write protect voltage 02 = VCC = 4.75 to 5.5V; VPFD = 4.5 to 4.75V 12 = VCC = 4.5 to 5.5V; VPFD = 4.2 to 4.5V
Speed -70 = 100ns (M48T02/12) -150 = 150ns (M48T02/12) -200 = 200ns (M48T02/12)
Package PC = PCDIP24
Temperature range 1 = 0 to 70C
Shipping method blank = ECOPACK package, tubes
For other options, or for more information on any aspect of this device, please contact the ST sales office nearest you.
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M48T02, M48T12
Revision history
8
Revision history
Table 14.
Date Jul-2000 13-Jul-2000 07-May-2001 14-May-01 16-Jul-2001 20-May-2002 26-Jun-2002 28-Mar-2003 31-Mar-2004 12-Dec-2005 21-Sep-2007
Document revision history
Revision 1.0 1.1 2.0 2.1 2.2 2.3 2.4 3.0 4.0 5.0 6 First issue trec change (Table 10) Reformatted; temp. / voltage info. added to tables (Table 8, 9, 3, 4, 10, 11) Note added to Clock Calibration section; table footnote correction (Table 2) Basic formatting / content changes (cover page, Table 8, 9) Add countries to disclaimer Add footnote to table (Table 11) v2.2 template applied; test conditions updated (Table 10) Reformatted; Lead-free (Pb-free) package information update (Table 6, 13) Updated template, Lead-free text, removed footnote (Table 9, 13) Added lead-free second level interconnect information to cover page and Section 6: Package mechanical data. Changes
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M48T02, M48T12
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