STMicroelectronics M48T251YPM 5.0 or 3.3v, 4096k timekeeper sram with phantom Datasheet

M48T251Y
M48T251V
5.0 or 3.3V, 4096K TIMEKEEPER® SRAM with PHANTOM
FEATURES SUMMARY
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■
■
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■
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■
5.0V OR 3.3V OPERATING VOLTAGE
REAL TIME CLOCK KEEPS TRACK OF
TENTHS/HUNDREDTHS OF SECONDS,
SECONDS, MINUTES, HOURS, DAYS,
DATE OF THE MONTH, MONTHS, AND
YEARS
AUTOMATIC LEAP YEAR CORRECTION
VALID UP TO THE YEAR 2100
AUTOMATIC SWITCH-OVER AND
DESELECT CIRCUITRY
CHOICE OF POWER-FAIL DESELECT
VOLTAGES:
(VPFD = Power-fail Deselect Voltage):
– M48T251Y: 4.25V ≤ VPFD ≤ 4.50V
– M48T251V: 2.80V ≤ VPFD ≤ 2.97V
FULL 10% VCC OPERATING RANGE
OVER 10 YEARS’ DATA RETENTION IN
THE ABSENCE OF POWER
WATCH FUNCTION IS TRANSPARENT TO
RAM OPERATION
512K x 8 NV SRAM DIRECTLY REPLACES
VOLATILE STATIC RAM OR EEPROM
February 2005
Figure 1. 32-pin, DIP Package
32
1
PMDIP32 (PM)
1/24
M48T251Y, M48T251V
TABLE OF CONTENTS
FEATURES SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Figure 1. 32-pin, DIP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
SUMMARY DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Figure 2.
Table 1.
Figure 3.
Figure 4.
Logic Diagram . .
Signal Names . .
DIP Connections
Block Diagram . .
...................
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...................
...................
.......
.......
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......
......
......
......
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.......
.......
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......
......
......
......
......
......
......
......
.....4
.....4
.....5
.....5
OPERATION MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Table 2. Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
READ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 5. Memory READ Cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
WRITE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 6. Memory WRITE Cycle 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 7. Memory WRITE Cycle 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 3. Memory AC Characteristics, M48T251Y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Table 4. Memory AC Characteristics, M48T251V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Data Retention Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
PHANTOM CLOCK OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 8. Comparison Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Clock Register Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Clock Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
AM-PM/12/24 Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Oscillator and Reset Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Zero Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Table 5. Phantom Clock Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 9. Phantom Clock READ Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 10.Phantom Clock WRITE Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 11.Phantom Clock Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Table 6. Phantom Clock AC Characteristics (M48T251Y). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 7. Phantom Clock AC Characteristics (M48T251V). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
MAXIMUM RATING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 8. Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
DC AND AC PARAMETERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 9. DC and AC Measurement Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Figure 12.AC Testing Load Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 10. Capacitance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 11. DC Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 13.Power Down/Up Mode AC Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2/24
M48T251Y, M48T251V
Table 12. Power Down/Up Trip Points DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
PACKAGE MECHANICAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 14.PMDIP32 – 32-pin Plastic Module DIP, Package Outline . . . . . . . . . . . . . . . . . . . . . . . . 21
Table 13. PMDIP32 – 32-pin Plastic Module DIP, Package Mechanical Data . . . . . . . . . . . . . . . . 21
PART NUMBERING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Table 14. Ordering Information Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
REVISION HISTORY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 15. Document Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3/24
M48T251Y, M48T251V
SUMMARY DESCRIPTION
The M48T251Y/V TIMEKEEPER® RAM is a
512Kbit x 8 non-volatile static RAM and real time
clock organized as 524,288 words by 8 bits. The
special DIP package provides a fully integrated
battery back-up memory and real time clock solution. In the event of power instability or absence, a
self-contained battery maintains the timekeeping
operation and provides power for a CMOS static
RAM. Control circuitry monitors VCC and invokes
write protection to prevent data corruption in the
memory and RTC.
The clock keeps track of tenths/hundredths of seconds, seconds, minutes, hours, day, date, month,
and year information. The last day of the month is
automatically adjusted for months with less than
31 days, including leap year correction.
The clock operates in one of two formats:
– a 12-hour mode with an AM/PM indicator;
or
– a 24-hour mode
The M48T251Y/V is a 32-pin (PM) DIP module
that integrates the RTC, the battery, and SRAM in
one package.
The modules are shipped in plastic, anti-static
tubes (see Table 14., page 22).
Figure 2. Logic Diagram
Table 1. Signal Names
A0–A18
VCC
RST
Reset Input
CE
Chip Enable
OE
Output Enable Input
WE
WRITE Enable Input
DQ0–DQ7
Data Inputs/Outputs
OE
VCC
Supply Voltage Input
RST
VSS
Ground
A0-A18
DQ0-D7
WE
CE
M48T251Y
M48T251V
VSS
AI04237
4/24
Address Input
M48T251Y, M48T251V
Figure 3. DIP Connections
A18/RST
1
32
VCC
A16
2
31
A15
A14
3
30
A17
A12
4
29
WE
A7
5
28
A13
A6
6
27
A8
A5
7
A4
8
M48T251Y
M48T251V
26
A9
25
A11
A3
9
24
OE
A2
10
23
A10
A1
11
22
CE
A0
12
21
DQ7
DQ0
13
20
DQ6
DQ1
14
19
DQ5
DQ2
15
18
DQ4
VSS
16
17
DQ3
AI04239
Figure 4. Block Diagram
XO
CLOCK/CALENDAR
LOGIC
32.768 Hz
CRYSTAL
XI
UPDATE
READ
CE
OE
WE
TIMEKEEPER
REGISTER
WRITE
CONTROL
LOGIC
POWER
FAIL
A0–A16
RST
SRAM
ACCESS
ENABLE
SEQUENCE
DETECTOR
DQ0
I/O
BUFFERS
DQ0–DQ7
COMPARISON
REGISTER
DATA
INTERNAL VCC
VCC
POWER-FAIL
DETECT
LOGIC
VBAT
AI04238
5/24
M48T251Y, M48T251V
OPERATION MODES
Table 2. Operating Modes
VCC
Mode
Deselect
4.5V to 5.5V
or
3.0V to 3.6V
WRITE
READ
READ
CE
OE
WE
DQ7-DQ0
Power
VIH
X
X
High-Z
Standby
VIL
X
VIL
DIN
Active
VIL
VIL
VIH
DOUT
Active
VIL
VIH
VIH
High-Z
Active
Deselect
VSO to VPFD (min)(1)
X
X
X
High-Z
CMOS Standby
Deselect
≤ VSO(1)
X
X
X
High-Z
Battery Back-Up
Note: X = VIH or VIL; VSO = Battery Back-up Switchover Voltage
1. See Table 12., page 20 for details.
READ
A READ cycle executes whenever WRITE Enable
(WE) is high and Chip Enable (CE) is low (see Figure 5.). The distinct address defined by the 19 address inputs (A0-A18) specifies which of the 512K
bytes of data is to be accessed. Valid data will be
accessed by the eight data output drivers within
the specified Access Time (tACC) after the last ad-
dress input signal is stable, the CE and OE access
times, and their respective parameters are satisfied. When CE tACC and OE tACC are not satisfied,
then data access times must be measured from
the more recent CE and OE signals, with the limiting parameter being tCO (for CE) or tOE (for OE) instead of address access.
Figure 5. Memory READ Cycle
tRC
ADDRESSES
tACC
tOH
tCO
CE
tOD
tOE
OE
tCOE
tODO
tCOE
DQ0 - DQ7
DATA OUTPUT
VALID
AI04230
Note: WE is high for a READ cycle.
6/24
M48T251Y, M48T251V
WRITE
WRITE Mode (see Figure 6.) occurs whenever CE
and WE signals are low (after address inputs are
stable). The most recent falling edge of CE and
WE will determine when the WRITE cycle begins
(the earlier, rising edge of CE or WE determines
cycle termination). All address inputs must be kept
stable throughout the WRITE cycle. WE must be
high (inactive) for a minimum recovery time (tWR)
before a subsequent cycle is initiated. The OE
control signal should be kept high (inactive) during
the WRITE cycles to avoid bus contention. If CE
and OE are low (active), WE will disable the outputs for Output Data WRITE Time (tODW) from its
falling edge.
Figure 6. Memory WRITE Cycle 1
tWC
ADDRESSES
tAW
CE
tWR
tWP
WE
tOEW
tODW
HIGH IMPEDANCE
DQ0–DQ7
tDH
tDS
DATA IN
STABLE
AI04231
Note: 1. OE = VIH or VIL. If OE = VIH during a WRITE cycle, the output buffers remain in a high impedance state.
2. 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.
3. If the CE high transition occurs simultaneously with the WE high transition, the output buffers remain in a high impedance state
during this period.
7/24
M48T251Y, M48T251V
Figure 7. Memory WRITE Cycle 2
WE = VIH
ADDRESSES
tWC
VIH
VIL
VIH
VIL
VIH
VIL
tAW
tWP
CE
VIH
VIL
tWR
VIL
VIH
tOEW
WE
VIL
VIL
tODW
tCOE
DQ0–DQ7
tDS
VIH
VIL
tDH
DATA IN
STABLE
VIH
VIL
AI04232
Note: 1. OE = VIH or VIL. If OE = VIH during a WRITE cycle, the output buffers remain in a high impedance state.
2. 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.
8/24
M48T251Y, M48T251V
Table 3. Memory AC Characteristics, M48T251Y
Parameter(1)
Symbol
M48T251Y–70
Unit
Min
Max
tAVAV
tRC
READ Cycle Time
tAVQV
tACC
Access Time
70
ns
tELQV
tCO
Chip Enable Low to Output Valid
70
ns
tGLQV
tOE
Output Enable Low to Output Valid
35
ns
tELQX
tGLQX
tCOE
Chip Enable or Output Enable Low to Output Transition
5
ns
tAXQX
tOH
Output Hold from Address Change
5
ns
tEHQZ
tGHQZ
tOD(2)
tWLQZ
tODW(2)
tAVAV
tWC
tWLWH
tELEH
70
ns
Chip Enable or Output Enable High to Output Hi-Z
25
ns
Output Hi-Z from WE
25
ns
WRITE Cycle Time
70
ns
tWP(3)
WE, CE Pulse Width
50
ns
tAVEL
tAVWL
tAW
Address Setup Time
0
ns
tEHAX
tWR1
WRITE Recovery Time
15
ns
tWHAX
tWR2
Address Hold Time from WE
0
ns
tWHQX
tOEW
Output Active from WE
5
ns
tDVEH
tDVWH
tDS(4)
Data Setup Time
30
ns
tWHDX
tDH1(4)
Data Hold Time from WE
0
ns
tEHDX
tDH2(4)
Data Hold Time from CE
10
ns
Note: 1. Valid for Ambient Operating Temperature: TA = 0 to 70°C; VCC = 4.5 to 5.5V or 3.0 to 3.6V (except where noted).
2. These parameters are sampled with a 5 pF load are not 100% tested.
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 and tDS are measured from the earlier of CE or WE going high.
9/24
M48T251Y, M48T251V
Table 4. Memory AC Characteristics, M48T251V
Parameter(1)
Symbol
M48T251V–85
Unit
Min
Max
tAVAV
tRC
READ Cycle Time
tAVQV
tACC
Access Time
85
ns
tELQV
tCO
Chip Enable Low to Output Valid
85
ns
tGLQV
tOE
Output Enable Low to Output Valid
45
ns
tELQX
tGLQX
tCOE
Chip Enable or Output Enable Low to Output Transition
5
ns
tAXQX
tOH
Output Hold from Address Change
5
ns
tEHQZ
tGHQZ
tOD(2)
tWLQZ
tODW(2)
tAVAV
tWC
tWLWH
tWP1(3)
tELEH
85
ns
Chip Enable or Output Enable High to Output Hi-Z
35
ns
Output Hi-Z from WE
30
ns
WRITE Cycle Time
85
ns
WRITE Enable Pulse Width
65
ns
tWP2
Chip Enable Pulse Width
75
ns
tAVEL
tAVWL
tAW
Address Setup Time
0
ns
tEHAX
tWR1(4)
WRITE Recovery Time
15
ns
tWHAX
tWR2
Address Hold Time from WE
5
ns
tWHQX
tOEW
Output Active from WE
5
ns
tDVEH
tDVWH
tDS(5)
Data Setup Time
35
ns
tWHDX
tDH1(5)
Data Hold Time from WE
0
ns
tEHDX
tDH2
Data Hold Time from CE
15
ns
Note: 1.
2.
3.
Valid for Ambient Operating Temperature: TA = 0 to 70°C; VCC = 4.5 to 5.5V or 3.0 to 3.6V (except where noted).
These parameters are sampled with a 5 pF load are not 100% tested.
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. tWR is a function of the latter occurring edge of WE or CE.
5. tDH and tDS are measured from the earlier of CE or WE going high.
10/24
M48T251Y, M48T251V
Data Retention Mode
Data can be read or written only when VCC is
greater than VPFD. When VCC is below VPFD (the
point at which write protection occurs), the clock
registers and the SRAM are blocked from any access. When VCC falls below the Battery Switch
Over threshold (VSO), the device is switched from
VCC to battery backup (VBAT). RTC operation and
SRAM data are maintained via battery backup until power is stable. All control, data, and address
signals must be powered down when VCC is powered down.
The lithium power source is designed to provide
power for RTC activity as well as RTC and RAM
data retention when VCC is absent or unstable.
The capability of this source is sufficient to power
the device continuously for the life of the equipment into which it has been installed. For specification purposes, life expectancy is ten (10) years
at 25°C with the internal oscillator running without
VCC. Each unit is shipped with its energy source
disconnected, guaranteeing full energy capacity.
When VCC is first applied at a level greater than
VPFD, the energy source is enabled for battery
backup operation. The actual life expectancy will
be much longer if no battery energy is used (e.g.,
when VCC is present).
PHANTOM CLOCK OPERATION
Communication with the Phantom Clock is established by pattern recognition of 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 clock while disabling the memory.
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 using
the CE and OE control of the clock starts the pattern recognition sequence by moving the pointer to
the first bit of the 64-bit comparison register (see
Figure 8., page 12).
Next, 64 consecutive WRITE cycles are executed
using the CE and WE control of the device. These
64 WRITE cycles are used only to gain access to
the clock. Therefore, any address to the memory
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 1 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 of the
bits in the comparison register have been
matched. With a correct match for 64-bits, the
Phantom Clock is enabled and data transfer to or
from the timekeeping registers can proceed. The
next 64 cycles will cause the Phantom Clock to either receive or transmit data on DQ0, depending
on the level of the OE pin or the WE pin. Cycles to
other locations outside the memory block can be
interleaved with CE cycles without interrupting the
pattern recognition sequence or data transfer sequence to the Phantom Clock.
11/24
M48T251Y, M48T251V
Figure 8. Comparison Register Definition
Hex
Value
7
6
5
4
3
2
1
0
BYTE 0
1
1
0
0
0
1
0
1
C5
BYTE 1
0
0
1
1
1
0
1
0
3A
BYTE 2
1
0
1
0
0
0
1
1
A3
BYTE 3
0
1
0
1
1
1
0
0
5C
BYTE 4
1
1
0
0
0
1
0
1
C5
BYTE 5
0
0
1
1
1
0
1
0
3A
BYTE 6
1
0
1
0
0
0
1
1
A3
BYTE 7
0
1
0
1
1
1
0
0
5C
AI04262
Note: The odds of this pattern being accidentally duplicated and sending aberrant entries to the RTC is less than 1 in 1019. This pattern is
sent to the clock LSB to MSB.
12/24
M48T251Y, M48T251V
Clock Register Information
AM-PM/12/24 Mode
Clock information is contained in eight registers of
8 bits, each of which is sequentially accessed one
(1) bit at a time after the 64-bit pattern recognition
sequence has been completed. When updating
the clock registers, each 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 the
clock register map (see Table 5.).
Data contained in the clock registers 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.
Bit 7 of the hours register is defined as the 12-hour
or 24-hour mode select bit. When it is high, the 12hour mode is selected. In the 12-hour mode, Bit 5
is the AM/PM bit with the 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 input. When the reset bit is set to logic '1,'
the Reset Input pin is ignored. When the reset bit
logic is set to '0,' a low input on the reset pin will
cause the device to abort data transfer without
changing data in the timekeeping registers. Reset
operates independently of all other inputs. Bit 5
controls the oscillator. When set to logic '0,' the oscillator turns on and the RTC/calendar begins to
increment.
Clock Accuracy
The RTC is guaranteed to keep time accuracy to
with ±1 minute per month at 25°C. The clock is factory-tuned with special calibration elements, and
does not require additional calibration. Moderate
temperature deviation will have a negligible effect
in most applications.
Zero Bits
Registers 1, 2, 3, 4, 5, and 6 contain one (1) or
more bits that will always read logic '0.' When writing to these locations, either a logic '1' or '0' is acceptable.
Table 5. Phantom Clock Register Map
Register
D7
0
D6
D5
D4
D3
0.1 Seconds
D2
D1
D0
Function/Range
BCD Format
0.01 Seconds
Seconds
00-99
1
0
10 Seconds
Seconds
Seconds
00-59
2
0
10 Minutes
Minutes
Minutes
00-59
3
12/24
0
10 /
A/P
Hrs
Hours (24 Hour Format)
Hours
01-12/
00-23
4
0
0
OSC
RST
Day
01-7
5
0
0
Date: Day of the Month
Date
01-31
6
0
0
Month
Month
01-12
Year
Year
00-99
7
10 date
0
10 Years
Keys: A/P = AM/PM Bit
12/24 = 12 or 24-hour mode Bit
OSC = Oscillator Bit
10M
0
Day of the Week
RST = Reset Bit
0 = Must be set to '0'
13/24
M48T251Y, M48T251V
Figure 9. Phantom Clock READ Cycle
WE
tRC
tCW
tRR
tCO
CE
tOD
tOW
OE
tODO
tOE
tOEE
tCOE
DATA OUTPUT VALID
Q
AI04259
Figure 10. Phantom Clock WRITE Cycle
OE
tWC
tWP
tWR
WE
tWR
tCW
CE
t DH
tDH
tDS
D
DATA INPUT STABLE
AI04261
Figure 11. Phantom Clock Reset
tRST
RST
AI04235
14/24
M48T251Y, M48T251V
Table 6. Phantom Clock AC Characteristics (M48T251Y)
Parameter(1)
Symbol
Min
Typ
Max
Unit
tAVAV
tRC
READ Cycle Time
tELQV
tCO
CE Access Time
55
ns
tGLQV
tOE
OE Access Time
55
ns
tELQX
tCOE
CE to Output Low Z
5
ns
tGLQX
tOEE
OE to Output Low Z
5
ns
tEHQZ
tOD(2)
CE to Output High Z
25
ns
tGHQZ
tODO(2)
OE to Output High Z
25
ns
65
ns
tRR
READ Recovery
10
ns
tAVAV
tWC
WRITE Cycle Time
65
ns
tWLWH
tWP(3)
WRITE Pulse Width
55
ns
tEHAX
tWR(4)
WRITE Recovery
10
ns
tDVEH
tDS(5)
Data Setup Time
30
ns
tWHDX
tDH1(5)
Data Hold Time from WE
0
ns
tEHDX
tDH2(5)
Data Hold Time from CE
0
ns
tELEH
tCW
CE Pulse Width
55
ns
tRST
RST Pulse Width
65
ns
Note: 1. Valid for Ambient Operating Temperature: TA = 0 to 70°C; VCC = 4.5 to 5.5V or 3.0 to 3.6V (except where noted).
2. These parameters are sampled with a 5 pF load and are not 100% tested.
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. tWR is a function of the latter occurring edge of WE or CE.
5. tDH and tDS are measured from the earlier of CE or WE going high.
15/24
M48T251Y, M48T251V
Table 7. Phantom Clock AC Characteristics (M48T251V)
Parameter(1)
Symbol
Min
Typ
Max
Unit
tAVAV
tRC
READ Cycle Time
tELQV
tCO
CE Access Time
85
ns
tGLQV
tOE
OE Access Time
85
ns
tELQX
tCOE
CE to Output Low Z
5
ns
tGLQX
tOEE
OE to Output Low Z
5
ns
tEHQZ
tOD(2)
CE to Output High Z
30
ns
tGHQZ
tODO(2)
OE to Output High Z
30
ns
85
ns
tRR
READ Recovery
20
ns
tAVAV
tWC
WRITE Cycle Time
85
ns
tWLWH
tWP(3)
WRITE Pulse Width
60
ns
tEHAX
tWR(4)
WRITE Recovery
20
ns
tDVEH
tDS(5)
Data Setup Time
35
ns
tWHDX
tDH1(5)
Data Hold Time from WE
0
ns
tEHDX
tDH2(5)
Data Hold Time from CE
0
ns
tELEH
tCW
CE Pulse Width
65
ns
tRST
RST Pulse Width
85
ns
Note: 1. Valid for Ambient Operating Temperature: TA = 0 to 70°C; VCC = 4.5 to 5.5V or 3.0 to 3.6V (except where noted).
2. These parameters are sampled with a 5 pF load and are not 100% tested.
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. tWR is a function of the latter occurring edge of WE or CE.
5. tDH and tDS are measured from the earlier of CE or WE going high.
16/24
M48T251Y, M48T251V
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 8. Absolute Maximum Ratings
Symbol
TA
Parameter
Operating Temperature
Value
Unit
0 to 70
°C
TSTG
Storage Temperature (VCC, Oscillator Off)
–40 to 85
°C
TSLD(1)
Lead Solder Temperature for 10 seconds
260
°C
M48T251Y
–0.3 to +7.0
V
M48T251V
–0.3 to +4.6
V
–0.3 to VCC + 0.3
V
VCC
Supply Voltage (on any
pin relative to Ground)
VIO
Input or Output Voltages
IO
Output Current
20
mA
PD
Power Dissipation
1
W
Note: 1. Soldering temperature not to exceed 260°C for 10 seconds (total thermal budget not to exceed 150°C for longer than 30 seconds).
No preheat above 150°C, or direct exposure to IR reflow (or IR preheat) allowed, to avoid damaging the Lithium battery.
CAUTION! Negative undershoots below -0.3V are not allowed on any pin while in the Battery Back-up Mode.
17/24
M48T251Y, M48T251V
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 Measure-
ment 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 9. DC and AC Measurement Conditions
Parameter
M48T251Y
M48T251V
4.5 to 5.5V
3.0 to 3.6V
0 to 70°C
0 to 70°C
Load Capacitance (CL)
100pF
50pF
Input Rise and Fall Times
≤ 5ns
≤ 5ns
0 to 3V
0 to 3V
1.5V
1.5V
VCC Supply Voltage
Ambient Operating Temperature
Input Pulse Voltages
Input and Output Timing Ref. Voltages
Note: Output High Z is defined as the point where data is no longer driven (see Table 9., page 18).
Figure 12. AC Testing Load Circuit
VCCI
1.1 KΩ
DEVICE
UNDER
TEST
680 Ω
CL = 50 pF
AI04240
Note: 50pF for M48T251V.
Table 10. Capacitance
Symbol
CIN
CIO(3)
Parameter(1,2)
Min
Max
Unit
Input Capacitance
10
pF
Input / Output Capacitance
10
pF
Note: 1. Effective capacitance measured with power supply at 5V. Sampled only; not 100% tested.
2. At 25°C, f = 1MHz.
3. Outputs were deselected.
18/24
M48T251Y, M48T251V
Table 11. DC Characteristics
Sym
(1)
Parameter
Test Condition
Min
M48T251Y
M48T251V
–70
–85
Typ
Max
±1
µA
0V ≤ VOUT ≤ VCC
±1
±1
µA
85
50
mA
ILO
Output Leakage Current
ICC1
Supply Current
ICC2
Supply Current (TTL
Standby)
ICC3
VCC Power Supply
Current
VIL(3)
Input Low Voltage
–0.3
0.8
VIH(3)
Input High Voltage
2.2
VCC + 0.3
VOL
Output Low Voltage
IOL = 2.0 mA
VOH
Output High Voltage
IOH = –1.0 mA
Battery Back-up
Switchover
Max
±1
Input Leakage Current
VSO(3)
Typ
0V ≤ VIN ≤ VCC
ILI(2)
VPFD(3) Power Fail Deselect
Min
Unit
CE = VIH
5
10
5
7
mA
CE = VCCI – 0.2
3
5
2
3
mA
–0.3
0.6
V
2.2
VCC + 0.3
V
0.4
V
0.4
2.4
4.25
2.4
4.37
VBAT
4.50
V
2.80
2.97
2.5
V
V
Note: 1. Valid for Ambient Operating Temperature: TA = 0 to 70°C; VCC = 4.5 to 5.5V or 3.0 to 3.6V (except where noted).
2. RST (Pin 1) has an internal pull-up resistor.
3. All voltages are referenced to Ground.
19/24
M48T251Y, M48T251V
Figure 13. Power Down/Up Mode AC Waveforms
VCC
tF
tR
VPFD (max)
VPFD (min)
VSO
tFB
tREC
tPD
CE
tDR
AI04236
Table 12. Power Down/Up Trip Points DC Characteristics
Symbol
Parameter(1)
Min
Max
Unit
VPFD (max) to CE low
1.5
2.5
ms
tF
VPFD (max) to VPFD (min) VCC Fall Time
300
µs
tFB
VPFD (min) to VSO VCC Fall Time
10
µs
tR
VPFD (min) to VPFD (max) VCC Rise Time
0
µs
CE High to Power-Fail
0
µs
Expected Data Retention Time
10
Years
tREC
tPD
tDR(2)
Note: 1. Valid for Ambient Operating Temperature: TA = 0 to 70°C; VCC = 4.5 to 5.5V or 3.0 to 3.6V (except where noted).
2. At 25°C, VCC = 0V; the expected tDR is defined as cumulative time in the absence of VCC with the clock oscillator running.
20/24
M48T251Y, M48T251V
PACKAGE MECHANICAL INFORMATION
Figure 14. PMDIP32 – 32-pin Plastic Module DIP, Package Outline
A
A1
B
S
L
C
eA
e1
e3
D
N
E
1
PMDIP
Note: Drawing is not to scale.
Table 13. 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
21/24
M48T251Y, M48T251V
PART NUMBERING
Table 14. Ordering Information Example
Example:
M48T
251Y
–70
PM
1
TR
Device Type
M48T
Supply Voltage and Write Protect Voltage
251Y = VCC = 4.5 to 5.5V; VPFD = 4.25 to 4.50V
251V = VCC = 3.0 to 3.6V; VPFD = 2.80 to 2.97V
Speed
–70 = 70ns (M48T251Y)
–85 = 85ns (M48T251V)
Package
PM = PMDIP32
Temperature Range
1 = 0 to 70°C
Shipping Method for SOIC
blank = Tubes
TR = Tape & Reel
For other options, or for more information on any aspect of this device, please contact the ST Sales Office
nearest you.
22/24
M48T251Y, M48T251V
REVISION HISTORY
Table 15. Document Revision History
Date
Version
Revision Details
June 2001
1.0
First Issue
20-May-02
1.1
Add countries to disclaimer
28-Mar-03
2.0
v2.2 template applied; test condition updated (Table 12)
22-Feb-05
3.0
Reformatted; IR reflow update (Table 8)
23/24
M48T251Y, M48T251V
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 life support devices or systems without express written approval of STMicroelectronics.
The ST logo is a registered trademark of STMicroelectronics.
All other names are the property of their respective owners
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24/24