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MK41T56
MKI41T56
512 bit (64b x8) Serial Access TIMEKEEPER
SRAM
March 1999
1/15
COUNTERS for SECONDS, MINUTES,
HOURS, DAY, DATE, MONTH and YEARS
SOFTWARE CLOCK CALIBRATION
AUTOMATIC POWER-FAIL DETECT and
SWITCH CIRCUITRY
I
2
C BUS COMPATIBLE
56 BYTES of GENERAL PURPOSE RAM
ULTRA-LOW BATTERY SUPPLY CURRENT of
500nA
OPERATING TEMPERATURE:
– MK41T56: 0 to 70
°
C
– MKI41T56: –40 to 85°C
AUTOMATIC LEAP YEAR COMPENSATION
DESCRIPTION
The MK41T56 TIMEKEEPER
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 MK41T56 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 button cell.
AI02304
OSCI
VCC
MK41T56
MKI41T56
VSS
SCL
OSCO
SDA
FT/OUT
VBAT
Figure 1. Logic Diagram
OSCI
Oscillator Input
OCSO
Oscillator Output
FT/OUT
Frequency Test / Output Driver
(Open Drain)
SDA
Serial Data Address Input / Output
SCL
Serial Clock
V
BAT
Battery Supply Voltage
V
CC
Supply Voltage
V
SS
Ground
Table 1. Signal Names
8
1
PSDIP8 (N)
0.4mm Frame
8
1
SO8 (S)
150mil Width