m48t18 STMicroelectronics, m48t18 Datasheet - Page 17

• Manufacturer Part Number: m48t18
• Description: 5v, 64kbit 8 Kb X 8 Timekeeper Sram
• Manufacturer: STMicroelectronics

Figure 8.
Figure 9.
V
CC
noise and negative going transients
NORMAL
POSITIVE
CALIBRATION
NEGATIVE
CALIBRATION
Crystal accuracy across temperature
Clock calibration
I
fluctuations, resulting in spikes on the V
capacitors are used to store energy which stabilizes the V
bypass capacitors will be released as low going spikes are generated or energy will be
absorbed when overshoots occur. A ceramic bypass capacitor value of 0.1µF (as shown in
Figure
In addition to transients that are caused by normal SRAM operation, power cycling can
generate negative voltage spikes on V
one volt. These negative spikes can cause data corruption in the SRAM while in battery
backup mode. To protect from these voltage spikes, it is recommended to connect a
schottky diode from V
CC
transients, including those produced by output switching, can produce voltage
-100
ppm
-20
-40
-60
-80
20
0
10) is recommended in order to provide the needed filtering.
0
5
10
F
F = -0.038
CC
15
to V
T
20
0
SS
ppm
= 25 C
C
2
(cathode connected to V
25
(T - T
30
0
)
CC
2
CC
35
10%
that drive it to values below V
bus. These transients can be reduced if
40
45
50
CC
CC
55
, anode to V
bus. The energy stored in the
60
65
AI02124
SS
70
SS
by as much as
). Schottky diode
AI00594B
C
17/30