M48T35-70MH1E STMICROELECTRONICS [STMicroelectronics], M48T35-70MH1E Datasheet - Page 11

• Manufacturer Part Number: M48T35-70MH1E
• Description: 5V, 256 Kbit (32 Kb x 8) TIMEKEEPER SRAM
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Table 4.
1. Valid for Ambient Operating Temperature: T
2. C
3. If E goes low simultaneously with W going low, the outputs remain in the high impedance state.
2.3
Note:
t
t
WHQX
WLQZ
Symbol
t
t
t
t
t
t
t
t
t
noted).
t
WLWH
WHDX
WHAX
DVWH
AVWH
EHDX
ELEH
EHAX
DVEH
AVEH
L
= 5pF.
(2)(3)
(2)(3)
WRITE Enable Pulse Width
Chip Enable Low to Chip Enable High
WRITE Enable High to Address Transition
Chip Enable High to Address Transition
Input Valid to WRITE Enable High
Input Valid to Chip Enable High
WRITE Enable High to Input Transition
Chip Enable High to Input Transition
WRITE Enable Low to Output Hi-Z
Address Valid to WRITE Enable High
Address Valid to Chip Enable High
WRITE Enable High to Output Transition
Write mode AC characteristics (continued)
Data retention mode
With valid V
Should the supply voltage decay, the RAM will automatically power-fail deselect, write
protecting itself when V
become high impedance, and all inputs are treated as “Don't care” (see
page
A power failure during a WRITE cycle may corrupt data at the currently addressed location,
but does not jeopardize the rest of the RAM's content. At voltages below V
user can be assured the memory will be in a write protected state, provided the V
is not less than tF. The M48T35/Y may respond to transient noise spikes on V
into the deselect window during the time the device is sampling V
of the power supply lines is recommended.
When V
preserves data and powers the clock. The internal button cell will maintain data in the
M48T35/Y for an accumulated period of at least 7 years when V
system power returns and V
supply is switched to external V
plus t
WRITE Cycles prior to processor stabilization. Normal RAM operation can resume t
V
For more information on Battery Storage Life refer to the Application Note AN1012.
CC
exceeds V
rec
19,
CC
(min). E should be kept high as V
Table
drops below V
CC
Parameter
applied, the M48T35/Y operates as a conventional BYTEWIDE static RAM.
PFD
10, and
(max).
CC
Table 11 on page
(1)
SO
A
falls within the V
= 0 to 70 or –40 to 85°C; V
CC
, the control circuit switches power to the internal battery which
rises above V
CC
. Write protection continues until V
20).
CC
PFD
SO
rises past V
(max), V
, the battery is disconnected, and the power
CC
Min
60
50
55
30
30
60
0
0
5
5
5
= 4.75 to 5.5V or 4.5 to 5.5V (except where
M48T35/Y
PFD
PFD
(min) window. All outputs
(min) to prevent inadvertent
CC
CC
Max
25
is less than V
. Therefore, decoupling
CC
reaches V
Figure 12 on
PFD
CC
(min), the
CC
SO
that reach
PFD
Unit
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
. As
rec
fall time
(min)
after
11/29