Datasheet

M48T201Y, M48T201V Operation
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Table 3. Read mode AC characteristics
2.3 Write mode
The M48T201Y/V is in the WRITE mode whenever W (WRITE enable) and E (chip enable)
are low state after the address inputs are stable. The start of a WRITE is referenced from
the latter occurring falling edge of W
or E. A WRITE is terminated by the earlier rising edge
of W
or E. The addresses must be held valid throughout the cycle. E or W must return high
for a minimum of t
EHAX
from chip enable or t
WHAX
from WRITE enable prior to the initiation
of another READ or WRITE cycle. Data-in must be valid t
DVWH
prior to the end of WRITE
and remain valid for t
WHDX
afterward. G should be kept high during WRITE cycles to avoid
bus contention; although, if the output bus has been activated by a low on E
and G a low on
W
will disable the outputs t
WLQZ
after W falls.
When the address value presented to the M48T201Y/V during the WRITE is in the range of
7FFFFh-7FFF0h, one of the on-board TIMEKEEPER
®
registers will be selected and data
will be written into the device. When the address value presented to M48T201Y/V is outside
the range of TIMEKEEPER registers, an external SRAM location is selected.
Symbol Parameter
(1)
1. Valid for ambient operating temperature: T
A
= 0 to 70°C; V
CC
= 4.5 to 5.5 V or 3.0 to 3.6 V (except where
noted).
M48T201Y M48T201V
Unit–70 –85
Min Max Min Max
t
AVAV
READ cycle time 70 85 ns
t
AVQV
Address valid to output valid 70 85 ns
t
ELQV
Chip enable low to output valid 70 85 ns
t
GLQV
Output enable low to output valid 25 35 ns
t
ELQX
(2)
2. C
L
= 5 pF.
Chip enable low to output transition 5 5 ns
t
GLQX
(2)
Output enable low to output transition 0 0 ns
t
EHQZ
(2)
Chip enable high to output Hi-Z 20 25 ns
t
GHQZ
(2)
Output enable high to output Hi-Z 20 25 ns
t
AXQX
Address transition to output transition 5 5 ns
t
AOEL
External SRAM address to G
CON
low 20 30 ns
t
AOEH
Supervisor SRAM address to G
CON
high 20 30 ns
t
EPD
E to E
CON
low or high 10 15 ns
t
OERL
G low to G
CON
low 15 20 ns
t
RO
G high to G
CON
high 10 15 ns