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KM416C254D, KM416V254D
CMOS DRAM
An initial pause of 200us is required after power-up followed by any 8 RAS-only refresh or CAS-before-RAS refresh cycles
before proper device operation is achieved.
V
IH
(min) and V
IL
(max) are reference levels for measuring timing of input signals.
Transition times are measured between V
IH
(min) and V
IL
(max) and are assumed to be 2ns for all inputs.
Measured with a load equivalent to 2 TTL(5V)/1 TTL(3.3V) loads and 50pF.
Operation within the
t
RCD
(max) limit insures that
t
RAC
(max) can be met.
t
RCD
(max) is specified as a reference point only.
If
t
RCD
is greater than the specified
t
RCD
(max) limit, then access time is controlled exclusively by
t
CAC
.
Assumes that
t
RCD
≥
t
RCD
(max).
This parameter defines the time at which the output achieves the open circuit condition and is not referenced to V
oh
or V
ol
.
t
WCS
,
t
RWD
,
t
CWD
,
t
AWD
and
t
CPWD
are non restrictive operating parameters. They are included in the data sheet as electrical
characteristics only. If
t
WCS
≥
t
WCS
(min), the cycle is an early write cycle and the data output will remain high impedance for
the duration of the cycle. If
t
CWD
≥
t
CWD
(min),
t
RWD
≥
t
RWD
(min),
t
AWD
≥
t
AWD
(min) and
t
CPWD
≥
t
CPWD
(min) then the cycle is a
read-modify-write cycle and the data output will contain the data read from the selected address. If neither of the above con-
ditions is satisfied, the condition of the data out is indeterminate.
Either
t
RCH
or
t
RRH
must be satisfied for a read cycle.
These parameters are referenced to the first CAS falling edge in early write cycles and to W falling edge in OE controlled
write cycle and read-modify-write cycles.
Operation within the
t
RAD
(max) limit insures that
t
RAC
(max) can be met.
t
RAD
(max) is specified as a reference point only.
If
t
RAD
is greater than the specified
t
RAD
(max) limit, then access time is controlled by
t
AA
.
t
ASC
≥
6ns, Assume t
T
= 2.0ns
If
RAS
goes high before CAS high going, the open circuit condition of the output is achieved by CAS high going. If CAS
goes
high before RAS high going, the open circuit condition of the output is achieved by RAS going.
KM416C/V254D/DL Truth Table
RAS
H
LCAS
H
UCAS
H
W
H
OE
H
DQ0 - DQ7
Hi-Z
DQ8-DQ15
Hi-Z
STATE
Standby
L
H
H
H
H
Hi-Z
Hi-Z
Refresh
L
L
H
H
L
DQ-OUT
Hi-Z
Byte Read
L
H
L
H
L
Hi-Z
DQ-OUT
Byte Read
L
L
L
H
L
DQ-OUT
DQ-OUT
Word Read
L
L
H
L
H
DQ-IN
-
Byte Write
L
H
L
L
H
-
DQ-IN
Byte Write
L
L
L
L
H
DQ-IN
DQ-IN
Word Write
L
L
L
H
H
Hi-Z
Hi-Z
-
7.
6.
5.
10.
9.
8.
12.
11.
3.
2.
1.
4.
NOTES