M48T128 ST Microelectronics, M48T128 Datasheet - Page 11

• Manufacturer Part Number: M48T128
• Description: 3.3V-5V 1 Mbit 128Kb x8 TIMEKEEPER SRAM
• Manufacturer: ST Microelectronics

Table 11. Register Map
Keys:
Figure 10. Calibration Waveform
POWER SUPPLY DECOUPLING
and UNDERSHOOT PROTECTION
Note: I
output switching, can produce voltage fluctua-
tions, resulting in spikes on the V
transients can be reduced if capacitors are used to
store energy, which stabilizes the V
energy stored in the bypass capacitors will be re-
leased as low going spikes are generated or ener-
gy will be absorbed when overshoots occur. A
ceramic bypass capacitor value of 0.1µF is recom-
mended in order to provide the needed filtering. In
Address
1FFFEh
1FFFDh
1FFFCh
1FFFBh
1FFFFh
1FFFAh
1FFF9h
1FFF8h
S = SIGN Bit
R = READ Bit
W = WRITE Bit
ST = STOP Bit
CC
NORMAL
POSITIVE
CALIBRATION
NEGATIVE
CALIBRATION
transients, including those produced by
D7
ST
W
0
0
0
0
0
D6
R
0
0
0
0
10 Years
10 Seconds
10 Minutes
D5
S
0
0
10 Hours
10 Date
CC
10 M.
D4
CC
0
bus. These
Data
bus. The
D3
0
Calibration
D2
Seconds
Minutes
addition to transients that are caused by normal
SRAM operation, power cycling can generate neg-
ative voltage spikes on V
below V
spikes can cause data corruption in the SRAM
while in battery backup mode. To protect from
these voltage spikes, ST recommends connecting
a schottky diode from V
nected to V
1N5817 is recommended for through hole and
MBRS120T3 is recommended for surface mount).
Month
Hours
Date
Year
Day
D1
0 = Must be set to zero
Z = ’0’ and are Read only
Y = ’1’ or ’0’
SS
by as much as one volt. These negative
CC
D0
, anode to V
Seconds
M48T128Y, M48T128V
Minutes
Control
Month
CC
Date
Hour
Year
Day
CC
Function/Range
to V
that drive it to values
BCD Format
SS
). (Schottky diode
SS
(cathode con-
AI00594B
00-99
01-12
01-31
01-07
00-23
00-59
00-59
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