Features: ` 5.0 OR 3.0V OPERATING VOLTAGE
` SERIAL PERIPHERAL INTERFACE (SPI)
` NVRAM SUPERVISOR FOR EXTERNAL LPSRAM
` 2.5 TO 5.5V OSCILLATOR OPERATING VOLTAGE
` AUTOMATIC SWITCH-OVER AND DESELECT CIRCUITRY
` CHOICE OF POWER-FAIL DESELECT VOLTAGES:
M41ST95Y*: VCC = 4.5 to 5.5V
4.20V VPFD 4.50V
M41ST95W: VCC = 2.7 to 3.6V
2.55V VPFD 24.70V
` 1.25V REFERENCE (FOR PFI/PFO)
` COUNTERS FOR TENTHS/HUNDREDTHS OF SECONDS, SECONDS, MINUTES
HOURS, DAY, DATE, MONTH, YEAR, AND CENTURY
` 44 BYTES OF GENERAL PURPOSE RAM
` PROGRAMMABLE ALARM and INTERRUPT FUNCTION (VALID EVEN DURING BATTERY BACK-UP MODE)
` WATCHDOG TIMER
` MICROPROCESSOR POWER-ON RESET
` BATTERY LOW FLAG
` 32kHz FREQUENCY OUTPUT AVAILABLE
IMMEDIATELY UPON POWER-ON (300mil SO28 MX PACKAGE ONLY)
` AUTOMATICALLY RECORDS TIME WHEN POWER-FAIL OCCURS
` ULTRA-LOW BATTERY SUPPLY CURRENT OF 550nA (MAX)
` PACKAGING INCLUDES A 28-LEAD SOIC and SNAPHAT® TOP (to be ordered separately)
` SOIC PACKAGE PROVIDES DIRECT
CONNECTION FOR A SNAPHAT TOP
WHICH CONTAINS THE BATTERY and CRYSTAL Pinout
Specifications
|
Symbol |
Parameter |
Value |
Unit |
|
TSTG |
Storage Temperature (VCC Off, Oscillator Off) |
55 to 125 |
|
|
VCC |
Supply Voltage |
M41ST95Y |
0.3 to 7 |
V |
| M41ST95W |
0.3 to 4.6 |
V |
|
TSLD |
Lead Solder Temperature for 10 seconds |
Lead-free lead finish(1) |
260 |
|
Standard (SnPb)
lead finish(2,3) |
240 |
|
|
TSLD (1,2) |
Lead Solder Temperature for 10 seconds |
260 |
|
|
VIO |
Input or Output Voltages |
0.3 to VCC +0.3 |
V |
|
IO |
Output Current |
20 |
mA |
|
PD |
Power Dissipation |
1 |
W |
Note: 1. For SOH28 package, Lead-free (Pb-free) lead finish: Reflow at peak temperature of 260 (total thermal budget not to exceed 245 for greater than 30 seconds).
2. For SOH28 package, standard (SnPb) lead finish: Reflow at peak temperature of 225 (total thermal budget not to exceed 180 for between 90 to 150 seconds).
3. The SOX28 package has Lead-free (Pb-free) lead finish, but cannot be exposed to peak reflow temperature in excess of 240 (use same reflow profile as standard (SnPb) lead finish).
CAUTION: Negative undershoots below 0.3V are not allowed on any pin while in the Battery Back-up mode.
CAUTION: Do NOT wave solder SOIC to avoid damaging SNAPHAT sockets.DescriptionThe M41ST95Y/W Serial TIMEKEEPER® SRAM is a low power, 512-bit static CMOS SRAM organized as 64 words by 8 biT. A built-in 32,768Hz oscillator (external crystal controlled) and 8 bytes of the SRAM M41ST95Y/W (see Table 4., page 16) are used for the clock/calendar function and are configured in binary coded decimal (BCD) format.
An additional 12 bytes of RAM M41ST95Y/W provide status/control of Alarm, Watchdog and Square Wave functions. Addresses and data are transferred serially via a serial SPI interface. The built-in address register is incremented automatically after each WRITE or READ data byte. The M41ST95Y/W has a built-in power sense circuit which detects power failures and automatically switches to the battery supply when a power failure occurs. The energy needed to sustain the SRAM and clock operations can be supplied by a small lithium buttoncell supply when a power failure occurs. Functions available to the user include a non-volatile, timeof- day clock/calendar, Alarm interrupts, Watchdog Timer and programmable Square Wave output. Other features of M41ST95Y/W 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 locations 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 M41ST95Y/W is supplied in a 28-lead SOIC SNAPHAT® (MH) package (which integrates both crystal and battery in a single SNAPHAT top), or a 28-pin, 300mil SOIC M41ST95Y/W package (MX) which includes an embedded 32kHz crystal.
The 28-pin, 330mil SOIC provides sockets with gold plated contacts at both ends for direct connection to a separate SNAPHAT housing containingthe battery and crystal. The unique design of M41ST95Y/W 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 M41ST95Y/W housing after reflow prevents potential battery and crystal damage due to the high temperatures required for device surface- mounting. The SNAPHAT M41ST95Y/W housing is also keyed to prevent reverse insertion.
The SNAPHAT SOIC M41ST95Y/W and battery/crystal packages are shipped separately in plastic anti-static tubes or in Tape & Reel form. For the 28-lead SOIC, the battery/crystal package (e.g., SNAPHAT) part number is "M4TXX-BR12SH"M41ST95Y/W (see Table 20., page 33).
Caution: Do not place the SNAPHAT battery/crystal top in conductive foam, as this will drain the lithium button-cell battery.
The 300mil, embedded crystal SOIC M41ST95Y/W requires only a user-supplied battery to provide non-volatile operation.
M41ST95Y Data Sheet
