M48Z128 Просмотр технического описания (PDF) - STMicroelectronics
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M48Z128 Datasheet PDF : 17 Pages
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M48Z128, M48Z128Y
Table 10. Write Mode AC Characteristics
(TA = 0 to 70 °C; VCC = 4.75V to 5.5V or 4.5V to 5.5V)
M48Z128/M48Z128Y
Symbol
Parameter
-70
-85
-120
Min Max Min Max Min Max
tAVAV
Write Cycle Time
70
85
120
tAVWL
Address Valid to Write Enable Low
0
0
0
tAVEL
Address Valid to Chip Enable Low
0
0
0
tWLWH
Write Enable Pulse Width
55
65
85
tELEH
Chip Enable Low to Chip Enable High
55
75
100
tWHAX
Write Enable High to Address Transition 5
5
5
tEHAX
Chip Enable High to Address Transition 15
15
15
tDVWH
Input Valid to Write Enable High
30
35
45
tDVEH
Input Valid to Chip Enable High
30
35
45
tWHDX
Write Enable High to Input Transition
0
0
0
tEHDX
Chip Enable High to Input Transition
10
10
10
tWLQZ (1, 2) Write Enable Low to Output Hi-Z
25
30
40
tAVWH
Address Valid to Write Enable High
65
75
100
tAVEH
Address Valid to Chip Enable High
65
75
100
tWHQX (1, 2) Write Enable High to Output Transition
5
5
5
Note: 1. CL = 5pF.
2. If E goes low simultaneously with W going low after W going low, the outputs remain in the high impedance state.
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
POWER SUPPLY DECOUPLING
and UNDERSHOOT PROTECTION
ICC transients, including those produced by output
switching, can produce voltage fluctuations, re-
sulting in spikes on the VCC bus. These transients
can be reduced if capacitors are used to store en-
ergy, which stabilizes the VCC 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 (as shown in Figure
9) is recommended in order to provide the needed
filtering.
In addition to transients that are caused by normal
SRAM operation, power cycling can generate neg-
ative voltage spikes on VCC that drive it to values
below VSS by as much as one Volt. These nega-
tive spikes can cause data corruption in the SRAM
while in battery backup mode. To protect from
these voltage spikes, it is recommended to con-
nect a schottky diode from VCC to VSS (cathode
connected to VCC, anode to VSS). Schottky diode
1N5817 is recommended for through hole and
MBRS120T3 is recommended for surface mount.
Figure 9. Supply Voltage Protection
VCC
0.1µF
VCC
DEVICE
VSS
AI02169
9/17
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