M48Z35AV-10PC1 Datasheet, PDF (13/20 Pages) STMicroelectronics – 256 Kbit (32 Kbit x 8) ZEROPOWER SRAM

M48Z35, M48Z35Y
Table 10. Power Down/Up Trip Points DC Characteristics
Symbol
Parameter⁽¹⁾
Min
Typ
Max
Unit
V_PFD Power-fail Deselect Voltage
M48Z35
4.5
M48Z35Y
4.2
4.6
4.75
V
4.35
4.5
V
V_SO
Battery Back-up Switchover Voltage M48Z35/Y
3.0
V
t_DR(2)
Expected Data Retention Time
10
YEARS
Note: All voltages referenced to V_SS.
1. Valid for Ambient Operating Temperature: TA = 0 to 70°C or –40 to 85°C; VCC = 4.75 to 5.5V or 4.5 to 5.5V (except where noted).
2. At 25°C.
V_CC Noise And Negative Going Transients
I_CC transients, including those produced by output
switching, can produce voltage fluctuations, re-
sulting in spikes on the V_CC bus. These transients
can be reduced if capacitors are used to store en-
ergy which stabilizes the V_CC bus. The energy
stored in the bypass capacitors will be released as
low going spikes are generated or energy will be
absorbed when overshoots occur. A ceramic by-
pass capacitor value of 0.1µF (see Figure 12) is
recommended in order to provide the needed fil-
tering.
In addition to transients that are caused by normal
SRAM operation, power cycling can generate neg-
ative voltage spikes on V_CC that drive it to values
below V_SS by as much as one volt. These negative
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_CC to V_SS (cathode con-
nected to V_CC, anode to V_SS). (Schottky diode
1N5817 is recommended for through hole and
MBRS120T3 is recommended for surface mount).
Figure 12. Supply Voltage Protection
VCC
0.1µF
VCC
DEVICE
VSS
AI02169
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