M48Z35-70MH1TR STMICROELECTRONICS [STMicroelectronics], M48Z35-70MH1TR Datasheet - Page 12

• Manufacturer Part Number: M48Z35-70MH1TR
• Description: 256 Kbit (32 Kbit x 8) ZEROPOWER SRAM
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

M48Z35, M48Z35Y
Data Retention Mode
With valid V
a conventional BYTEWIDE™ static RAM. Should
the supply voltage decay, the RAM will automati-
cally power-fail deselect, write protecting itself
when V
window. All outputs become high impedance, and
all inputs are treated as “don't care.”
Note: 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 con-
tent. At voltages below V
assured the memory will be in a write protected
state, provided the V
The M48Z35/Y may respond to transient noise
spikes on V
during the time the device is sampling V
Figure 11. Power Down/Up Mode AC Waveforms
Table 9. Power Down/Up AC Characteristics
Note: 1. Valid for Ambient Operating Temperature: T
12/20
Symbol
t
t
REC
t
FB
t
t
2. V
3. V
4. t
F
PD
t
RB
(2)
R
(3)
(4)
es V
REC
CC
PFD
PFD
V CC
V PFD (max)
V PFD (min)
V SO
INPUTS
OUTPUTS
PFD
(min) = 20ms for industrial temperature Grade (6) device.
falls within the V
(max) to V
(min) to V
CC
CC
E or W at V
V
V
V
V
V
(min).
that reach into the deselect window
applied, the M48Z35/Y operates as
PFD
PFD
PFD
SS
PFD
to V
(max) to V
(min) to V
(min) to V
(max) to Inputs Recognized
SS
PFD
tPD
CC
PFD
fall time of less than t
(PER CONTROL INPUT)
(min) fall time of less than t
IH
fall time is not less than t
PFD
(min) V
VALID
before Power Down
RECOGNIZED
SS
PFD
PFD
(min), the user can be
Parameter
PFD
tF
V
(max) V
CC
CC
(min) V
(max), V
Rise Time
Fall Time
FB
CC
CC
(1)
CC
may cause corruption of RAM data.
A
Rise Time
Fall Time
PFD
tFB
= 0 to 70°C or –40 to 85°C; V
. There-
F
may result in deselection/write protection not occurring until 200µs after V
(min)
F
.
fore, decoupling of the power supply lines is rec-
ommended.
When V
switches power to the internal battery which pre-
serves data. The internal button cell will maintain
data in the M48Z35/Y for an accumulated period of
at least 10 years (at 25°C) when V
V
As system power returns and V
V
supply is switched to external V
tion continues until V
t
t
For more information on Battery Storage Life refer
to the Application Note AN1012.
REC
REC
tDR
SO
SO
.
, the battery is disconnected, and the power
(min). Normal RAM operation can resume
after V
DON'T CARE
HIGH-Z
Min
300
10
10
40
CC
0
1
CC
= 4.75 to 5.5V or 4.5 to 5.5V (except where noted).
CC
drops below V
tRB
exceeds V
CC
Max
200
reaches V
PFD
SO
tR
(PER CONTROL INPUT)
(max).
, the control circuit
tREC
RECOGNIZED
CC
VALID
CC
CC
. Write protec-
PFD
AI01168C
rises above
is less than
(min) plus
Unit
ms
µs
µs
µs
µs
µs
CC
pass-