The M48T59/Y/V TIMEKEEPER® RAM is an
8 Kb x8 non-volatile static RAM and real time
clock. The monolithic chip is available in two special packages to provid e a highly integrated battery backed-up memory and real time clock
solution.
The M48T59/Y/V is a non-volatile pin and function
equivalent to any JEDEC standard 8 Kb x8 SRAM.
It also easi ly fits into many ROM, EPROM, and
EEPROM sockets, providing the non-volatility of
PROMs without any requirement for special write
timing or limitations on t he number of writes that
can be performed.
The 28-pin, 600mil DIP CAPHAT™ houses the
M48T59/Y/V silicon with a quartz crystal and a
long life lithium button cell in a single package.
The 28-pin, 330mil SOIC provides sockets with
gold plated contacts at bot h ends for direct connection to a separate SNAPHAT
®
housing con-
Figure 3. Logic DiagramTable 1. Signal Names
taining 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 c rystal dam age 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 anti-static tubes or in
Tape & Reel form. For the 2 8-lead SOIC, t he ba ttery/crystal package (e.g., SNAPHAT) part number is “M4T28-BR12SH” or “M4T32-BR12SH”
(see Table 19., page 27).
Caution: Do not place the SNAPHAT battery/crystal top in conductive foam, as this will drain the lithium button-cell battery.
Figure 4. 28-pi n S O I C Co nnectionsFigure 5. PC DIP 28 CA P H A T Connectio ns
RSTV
A12
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
1
2
3
4
5
6
7
8
9
10
11
M48T59Y
M48T59V
12
DQ2
SS
13
14
Figure 6. Block Diagram
32,768 Hz
CRYSTAL
28
27
26
25
24
23
22
21
20
19
18
17
16
15
AI01382E
OSCILLATOR AND
CLOCK CHAIN
CC
W
IRQ/FT
A8
A9
A11
G
A10
E
DQ7
DQ6
DQ5DQ1
DQ4
DQ3V
IRQ/FT
RSTV
1
A12
2
A7
3
A6
4
A5
5
A4
6
A3
7
A2
8
A1
9
A0
10
DQ0
11
12
DQ2
13
14
SS
16 x 8 BiPORT
SRAM ARRAY
M48T59
M48T59Y
28
27
26
25
24
23
22
21
20
19
18
17
16
15
AI01381D
CC
W
IRQ/FT
A8
A9
A11
G
A10
E
DQ7
DQ6
DQ5DQ1
DQ4
DQ3V
A0-A12
LITHIUM
CELL
VOLTAGE SENSE
AND
SWITCHING
CIRCUITRY
CC
RSTV
POWER
V
PFD
8176 x 8
SRAM ARRAY
V
SS
DQ0-DQ7
E
W
G
AI01383D
5/29
M48T59, M48T59Y, M48T59V*
OPERATION MODES
As Figure 6., page 5 shows, the static memory array and the quartz-controlled clock oscillator of the
M48T59/Y/V are integrated on one silicon chip.
The two circuits are interconnected at the upper
eight memory locations to provide user accessible
BYTEWIDE™ clock information in t he bytes with
addresses 1FF8h-1FFFh. The clock locations
contain the century, year, month, date, day, hour,
minute, and second in 24 hour BCD format (except
for the century). Corrections for 28, 29 (l eap year valid until 2100), 30, and 31 day months are made
automatically. Byte 1FF8h is the clock control register. This byte controls user access to the clock
information and also stores the clock calibration
setting.
The eight clock bytes are not the actual clock
counters themselves; they are memory locations
Table 2. Operating Modes
Mode
Deselect
WRITE
READ
READ
Deselect
Deselect
Note: X = VIH or VIL; VSO = Battery B ack-up Switc hover Voltage.
consisting of BiPORT™ READ/WRITE memory
cells. The M48T59/Y/V includes a clock control circuit which updates the clock bytes with current information once per second. The information can
be accessed by the user in the same manner as
any other location in the static memory array.
The M48T59/Y/V also has its ow n Power-fail Detect circuit. The control circuitry constantly monitors the single 5V/3.3V supply for an out of
tolerance condition. When V
is out of tolerance,
CC
the circuit write protects the SRAM, providing a
high degree of data security in the midst of unpredictable system operation brought on by low V
As V
Voltage (V
falls below the Battery Back-up Switchover
CC
), the control circuitry connects the
SO
battery which maintains data and cloc k operation
until valid power returns.
XXHigh ZStandby
X
V
IL
V
IH
V
IL
V
IH
V
IH
D
IN
D
OUT
High ZActive
Active
Active
CC
.
6/29
READ Mode
The M48T59/Y/V is in the READ M ode whenev er
(WRITE Enable) is high and E (Chip Enable) is
W
low. The unique address specified by the 13 address inputs defines which one of the 8,192 bytes
of data is to be acces sed . Vali d data w ill be av ailable at the Data I/O pi ns within Address Access
time (t
stable, providing that the E
are also satisfied. If the E
) after the last address input signal is
AVQV
and G access times
and G access times are
not met, valid data will be available after the latter
Figure 7. READ Mode AC Waveforms
M48T59, M48T59Y, M48T59V*
of the Chip Enable Access time (t
Enable Access time (t
GLQV
).
The state of the eight t hree-state Da ta I/O si gnals
is controlled by E
ed before t
indeterminate state until t
puts are changed while E
and G. If the outputs are activat-
, the data lines will be driven to an
AVQV
AVQV
and G remain active,
output dat a will re main valid for Ou tput D ata H old
time (t
) but will go indeterminate until the next
AXQX
Addr e ss Access.
tAVAV
ELQV
. If the Ad dres s In-
) or Output
A0-A12
tAVQVtAXQX
tELQV
E
tELQX
tGLQV
G
tGLQX
DQ0-DQ7
Note: W RITE Enable (W) = High.
VALID
tEHQZ
tGHQZ
VALID
AI01385
Table 3. READ Mode AC Characteristics
M48T59/Y/V
Symbol
t
AVAV
t
AVQV
t
ELQV
t
GLQV
t
ELQX
t
GLQX
t
EHQZ
t
GHQZ
t
AXQX
Note: 1. Valid for Ambient Operating Temperat ure: TA = 0 to 70°C; VCC = 4.5 to 5.5V, 4.7 5 to 5.5V, or 3.0 to 3.6V (except where noted) .
2. C
3. C
READ Cycle Time70ns
(2)
Address Valid to Output Valid70ns
(2)
Chip Enable Low to Output Valid70ns
(2)
Output Enable Low to Output Valid35ns
(3)
Chip Enable Low to Output Transition5ns
(3)
Output Enable Low to Output Transition5ns
(3)
Chip Enable High to Output Hi-Z25ns
(3)
Output Enable High to Output Hi-Z25ns
(2)
Address Transition to Output Transition10ns
= 100pF (see Figure 15 .,page 20).
L
= 5pF (see Figure 15., page 20).
L
Parameter
(1)
Unit–70
MinMax
7/29
M48T59, M48T59Y, M48T59V*
WRITE Mode
The M48T59/Y/V is in the WRITE Mode whenever
and E are low. The start of a WRITE is refer-
W
enced from the latter occurring falling edge of W
. A WRITE is terminated by the earlier rising
E
edge of W
throughout the cycle. E
a minimum of t
or E. The addresses must be held valid
or W must return high for
from Chip Enable or t
EHAX
or
WHAX
from WRITE Enable prior to the initiation of anoth-
Figure 8. WRITE Enable Controlled, WRITE Mode AC Waveforms
er READ or WRITE cycle. Data-in must be valid
t
for t
prior to the end of WRITE and remain valid
DVWH
afterward. G should be kept high during
WHDX
WRITE cycles to avoid bus contention; however, if
the output bus has b een activated by a low on E
and G a low on W will disable the outputs t
falls .
ter W
tAVAV
WLQZ
af-
A0-A12
tAVEL
E
tAVWL
W
tWLQZ
DQ0-DQ7
VALID
tAVWH
tWLWH
DATA INPUT
tDVWH
Figure 9. Chip Enable Controlled, WRITE Mode AC Waveforms
tAVAV
A0-A12
tAVEL
VALID
tAVEH
tELEH
tWHAX
tWHQX
tWHDX
AI01386
tEHAX
8/29
E
W
DQ0-DQ7
tAVWL
tDVEH
tEHDX
DATA INPUT
AI01387B
M48T59, M48T59Y, M48T59V*
Table 4. WRITE Mode AC Characteristics
M48T59/Y/V
Symbol
Parameter
(1)
MinMax
t
AVAV
t
AVWL
t
AVEL
t
WLWH
t
ELEH
t
WHAX
t
EHAX
t
DVWH
t
DVEH
t
WHDX
t
EHDX
(2,3)
t
WLQZ
t
AVWH
t
AVEH
(2,3)
t
WHQX
Note: 1. Valid for Ambient Operating Temperat ure: TA = 0 to 70°C; VCC = 4.5 to 5.5V, 4.7 5 to 5.5V, or 3.0 to 3.6V (except where noted) .
= 5pF (see Figure 15., page 20).
2. C
L
3. If E
WRITE Cycle Time70ns
Address Valid to WRITE Enable Low0ns
Address Valid to Chip Enable Low0ns
WRITE Enable Pulse Width50ns
Chip Enable Low to Chip Enable High55ns
WRITE Enable High to Address Transition0ns
Chip Enable High to Address Transition0ns
Input Valid to WRITE Enable High30ns
Input Valid to Chip Enable High30ns
WRITE Enable High to Input Transition5ns
Chip Enable High to Input Transition5ns
WRITE Enable Low to Output Hi-Z25ns
Address Valid to WRITE Enable High60ns
Address Valid to Chip Enable High60ns
WRITE Enable High to Output Transition5ns
goes low simultaneously with W going low , t he outputs remai n in the high impedance state.
Unit–70
9/29
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