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Part Number M41ST85Y

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1/33
May 2003
Rev. 4.0
M41ST85Y
M41ST85W
5.0 OR 3.0V, 512 bit (64 x 8) SERIAL
RTC and NVRAM SUPERVISOR
FEATURES SUMMARY
s
5.0 OR 3.0V OPERATING VOLTAGE
s
SERIAL INTERFACE SUPPORTS I
2
C BUS
(400 KHz)
s
NVRAM SUPERVISOR FOR EXTERNAL
LPSRAM
s
OPTIMIZED FOR MINIMAL INTERCONNECT
TO MCU
s
2.5 TO 5.5V OSCILLATOR OPERATING
VOLTAGE
s
AUTOMATIC SWITCH-OVER and DESELECT
CIRCUITRY
s
CHOICE OF POWER-FAIL DESELECT
VOLTAGES
­ M41ST85Y: V
CC
= 4.5 to 5.5V;
4.20V
V
PFD
4.50V
­ M41ST85W: V
CC
= 2.7 to 3.6V;
2.55V
V
PFD
2.70V
s
1.25V REFERENCE (for PFI/PFO)
s
COUNTERS FOR TENTHS/HUNDREDTHS
OF SECONDS, SECONDS, MINUTES,
HOURS, DAY, DATE, MONTH, YEAR, and
CENTURY
s
44 BYTES OF GENERAL PURPOSE RAM
s
PROGRAMMABLE ALARM and INTERRUPT
FUNCTION (VALID EVEN DURING BATTERY
BACK-UP MODE)
s
WATCHDOG TIMER
s
MICROPROCESSOR POWER-ON RESET
s
BATTERY LOW FLAG
s
POWER-DOWN TIMESTAMP (HT BIT)
s
ULTRA-LOW BATTERY SUPPLY CURRENT
OF 500nA (MAX)
s
PACKAGING INCLUDES A 28-LEAD SOIC and
SNAPHAT
®
TOP (to be Ordered Separately)
s
SOIC SNAPHAT PACKAGE PROVIDES
DIRECT CONNECTION FOR A SNAPHAT
TOP WHICH CONTAINS THE BATTERY and
CRYSTAL
s
SOIC EMBEDDED CRYSTAL PACKAGE (MX)
OPTION
Figure 1. 28-pin SOIC Package
Figure 2. 28-pin (300mil) SOIC Package
28
1
SOH28 (MH)
SNAPHAT (SH)
Battery & Crystal
SOX28 (MX)
EMBEDDED Crystal
M41ST85Y, M41ST85W
2/33
TABLE OF CONTENTS
SUMMARY DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Figure 3. Logic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Table 1. Signal Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 4. 28-pin SOIC Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 6. Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 7. Hardware Hookup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
MAXIMUM RATING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Table 2. Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
DC and AC PARAMETERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 3. DC and AC Measurement Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 8. AC Testing Input/Output Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 4. Capacitance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Table 5. DC Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
OPERATING MODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2-Wire Bus Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Figure 9. Serial Bus Data Transfer Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 11. WRITE Cycle Timing: RTC & External SRAM Control Signals . . . . . . . . . . . . . . . . . . . 12
Figure 12. Bus Timing Requirements Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Table 6. AC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
READ Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 13. Slave Address Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 14. READ Mode Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 15. Alternate READ Mode Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
WRITE Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 16. WRITE Mode Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Data Retention Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Figure 17. Power Down/Up Mode AC Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 7. Power Down/Up AC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
CLOCK OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
TIMEKEEPER® Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Table 8. TIMEKEEPER® Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Calibrating the Clock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Setting Alarm Clock Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 18. Alarm Interrupt Reset Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Table 9. Alarm Repeat Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 19. Back-Up Mode Alarm Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3/33
M41ST85Y, M41ST85W
Watchdog Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Square Wave Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Table 10. Square Wave Output Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Power-on Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Reset Inputs (RSTIN1 & RSTIN2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Figure 20. RSTIN1 & RSTIN2 Timing Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 11. Reset AC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Power-fail INPUT/OUTPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Century Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Output Driver Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Battery Low Warning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
t
REC
Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Initial Power-on Defaults. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Table 12. t
REC
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Table 13. Default Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 21. Crystal Accuracy Across Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 22. Calibration Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
PART NUMBERING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 15. SNAPHAT Battery Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
PACKAGE MECHANICAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
REVISION HISTORY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
M41ST85Y, M41ST85W
4/33
SUMMARY DESCRIPTION
The M41ST85Y/W Serial TIMEKEEPER
®
/Con-
troller SRAM is a low power 512-bit, static CMOS
SRAM organized as 64 words by 8 bits. A built-in
32.768 kHz oscillator (external crystal controlled)
and 8 bytes of the SRAM (see Table 8, page 18)
are used for the clock/calendar function and are
configured in binary coded decimal (BCD) format.
An additional 12 bytes of RAM provide status/con-
trol of Alarm, Watchdog and Square Wave func-
tions. Addresses and data are transferred serially
via a two line, bi-directional I
2
C interface. The
built-in address register is incremented automati-
cally after each WRITE or READ data byte. The
M41ST85Y/W has a built-in power sense circuit
which detects power failures and automatically
switches to the battery supply when a power fail-
ure occurs. The energy needed to sustain the
SRAM and clock operations can be supplied by a
small lithium button-cell supply when a power fail-
ure occurs.
Functions available to the user include a non-vol-
atile, time-of-day clock/calendar, Alarm interrupts,
Watchdog Timer and programmable Square
Wave output. Other features include a Power-On
Reset as well as two additional debounced inputs
(RSTIN1 and RSTIN2) which can also generate an
output Reset (RST). The eight clock address loca-
tions contain the century, year, month, date, day,
hour, minute, second and tenths/hundredths of a
second in 24 hour BCD format. Corrections for 28,
29 (leap year - valid until year 2100), 30 and 31
day months are made automatically.
The M41ST85Y/W is supplied in a 28-lead SOIC
SNAPHAT
®
package (which integrates both crys-
tal and battery in a single SNAPHAT top) or a 28-
pin, 300mil SOIC package (MX) which includes an
embedded 32kHz crystal.
The 28-pin, 330mil SOIC provides sockets with
gold plated contacts at both ends for direct con-
nection to a separate SNAPHAT housing contain-
ing the battery and crystal. The unique design
allows the SNAPHAT battery/crystal package to
be mounted on top of the SOIC package after the
completion of the surface mount process.
Insertion of the SNAPHAT housing after reflow
prevents potential battery and crystal damage due
to the high temperatures required for device sur-
face-mounting. The SNAPHAT housing is also
keyed to prevent reverse insertion.
The SOIC and battery/crystal packages are
shipped separately in plastic anti-static tubes or in
Tape & Reel form. For the 28-lead SOIC, the bat-
tery/crystal package (e.g., SNAPHAT) part num-
ber is "M4TXX-BR12SH" (see Table 15, page 27).
Caution: Do not place the SNAPHAT battery/crys-
tal top in conductive foam, as this will drain the lith-
ium button-cell battery.
The 300mil, embedded crystal SOIC requires only
a user-supplied battery to provide non-volatile op-
eration.
5/33
M41ST85Y, M41ST85W
Figure 3. Logic Diagram
Note: 1. For 28-pin, 300mil embedded crystal SOIC only.
Table 1. Signal Names
Note: 1. For 28-pin, 300mil embedded crystal SOIC only.
Figure 4. 28-pin SOIC Connections
Figure 5. 28-pin, 300mil SOIC (MX)
Connections
AI03658
SCL
VCC
M41ST85Y
M41ST85W
EX
VSS
VBAT
(1)
SDA
RSTIN1
IRQ/FT/OUT
SQW
WDI
RSTIN2
PFI
ECON
RST
PFO
VOUT
E
CON
Conditioned Chip Enable Output
EX
External Chip Enable
IRQ/FT/OUT
Interrupt/Frequency Test/Out Output
(Open Drain)
PFI
Power Fail Input
PFO
Power Fail Output
RST
Reset Output (Open Drain)
RSTIN1
Reset 1 Input
RSTIN2
Reset 2 Input
SCL
Serial Clock Input
SDA
Serial Data Input/Output
SQW
Square Wave Output
WDI
Watchdog Input
V
CC
Supply Voltage
V
OUT
Voltage Output
V
SS
Ground
V
BAT
(1)
Battery Supply Voltage
AI03659
8
2
3
4
5
6
7
9
10
11
12
13
14
22
21
20
19
18
17
16
15
28
27
26
25
24
23
1
RSTIN1
RSTIN2
NC
NC
NC
NC
WDI
NC
NC
IRQ/FT/OUT
NC
VOUT
NC
NC
EX
NC
PFI
SCL
NC
NC
PFO
ECON
VSS
SDA
RST
NC
SQW
VCC
M41ST85Y
M41ST85W
AI06370c
8
2
3
4
5
6
7
9
10
11
12
13
14
22
21
20
19
18
17
16
15
28
27
26
25
24
23
1
RSTIN1
RSTIN2
NC
NC
NC
NC
SQW
WDI
NC
NC
IRQ/FT/OUT
NC
VOUT
NC
EX
PFI
SCL
NC
PFO
ECON
VSS
VBAT
VSS
SDA
RST
NC
NC
VCC
M41ST85Y
M41ST85W