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The M41T11 TIMEKEEPER® RAM is a low power 512 bit static CMOS RAM organized as 64 words by 8 bits. A built-in 32.768 kHz oscillator (external crystal controlled) and the first 8 bytes of the RAM are used for the clock/calendar function and are configured in binary coded decimal (BCD) format. Addresses and data are transferred serially via a two-line bi-directional bus. The built-in address register is incremented automatically after each write or read data byte.
The M41T11 clock has a built-in power sense circuit which detects power failures and automatically switches to the battery supply during power failures. The energy needed to sustain the RAM and clock operations can be supplied from a small lithium coin cell.
Typical data retention time is in excess of 5 years with a 50mA/h 3V lithium cell. The M41T11 is supplied in 8 lead Plastic Small Outline package or 28 lead SNAPHAT package.
The 28 pin 330mil SOIC provides sockets with gold plated contacts at both ends for direct connection to a separate SNAPHAT housing containing the battery and crystal. The unique design allows the SNAPHAT battery 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 surfacemounting. The SNAPHAT housing is keyed to prevent reverse insertion. The SOIC and battery/crystal packages are shipped separately in plastic antistatic tubes or in Tape & Reel form.
For the 28 lead SOIC, the battery/crystal package (i.e. SNAPHAT) part number is "M4Txx- BR12SHx".
Caution: Do not place the SNAPHAT battery/crystal package "M4Txx-BR12SHx" in conductive foam since this will drain the lithium button-cell battery.
M41T11 Maximum Ratings
Symbol
Parameter
Value
Unit
TA
Ambient Operating Temperature
40 to 85
TSTG
Storage Temperature (VCC Off, Oscillator Off)
SNAPHAT
40 to 85
SOIC
55 to 125
TSLD (1)
Lead Solder Temperature for 10 seconds
260
VIO
Input or Output Voltage
0.3 to 7
V
VCC
Supply Voltage
0.3 to 7
V
IO
Output Current
20
mA
PD
Power Dissipation
0.25
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 for 10 seconds (total thermal budget not to exceed 150 for longer than 30 seconds). 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.
M41T11 Features
` 2.0V to 5.5V SUPPLY VOLTAGE ` COUNTERS for SECONDS, MINUTES, HOURS, DAY, DATE, MONTH, YEARS and CENTURY ` YEAR 2000 COMPLIANT ` SOFTWARE CLOCK CALIBRATION ` AUTOMATIC SWITCH-OVER and DESELECT CIRCUITRY ` I2C BUS COMPATIBLE ` 56 BYTES of GENERAL PURPOSE RAM ` ULTRA-LOW BATTERY SUPPLY CURRENT of 1A ` LOW OPERATING CURRENT of 300A ` OPERATING TEMPERATURE of 40 to 85 ` AUTOMATIC LEAP YEAR COMPENSATION ` SPECIAL SOFTWARE PROGRAMMABLE OUTPUT ` PACKAGING INCLUDES a 28-LEAD SOIC and SNAPHAT® TOP (to be Ordered Separately)