Am28F256A 9
FUNCTIONAL DESCRIPTION
Description Of User Modes
Table 1. Am28F256A Device Bus Operations (Notes 7 and 8)
Legend:
X = Don’t care, where Don’t Care is either V
IL
or V
IH
leve ls. V
PPL
= V
PP
<
V
CC
+ 2 V. See DC Characteristics for voltage levels
of V
PPH
. 0 V < An < V
CC
+ 2 V, (normal TTL or CMOS input levels, where n = 0 or 9).
Notes:
1. V
PPL
may be grounded, connected with a resistor to ground, or < V
CC
+ 2.0 V. V
PPH
is the programming v oltage specified for
the device. Refer to the DC characteristics. When V
PP
= V
PPL
, memory contents can be read but not written or erased.
2. Manufacturer and device codes may also be accessed via a command register write sequence. Refer to Table 2.
3. 11.5 < V
ID
< 13.0 V. Minimum V
ID
rise time and fall time (between 0 and V
ID
voltages) is 500 ns.
4. Read operation with V
PP
= V
PPH
may access array data or the Auto select codes.
5. With V
PP
at high voltage, the standby current is I
CC
+ I
PP
(standby).
6. Refer to Table 3 for valid D
IN
during a write operation.
7. All inputs are Don’t Care unless otherwise stated, where Don’t Care is either V
IL
or V
IH
levels. In the Auto select mode all
addresses except A
9
and A
0
must be held at V
IL
.
8. If V
CC
≤
1.0 Volt, the voltage difference between V
PP
and V
CC
should not exceed 10.0 volts. Also, the Am28F256 has a V
PP
rise time and fall time specification of 500 ns minimum.
Operation
CE#
(E#)
OE#
(G#)
WE#
(W#)
V
PP
(Note 1) A0 A9 I/O
Read-On ly
Read V
IL
V
IL
XV
PPL
A0 A9 D
OUT
Standby V
IH
XXV
PPL
X X HIGH Z
Output Disable V
IL
V
IH
V
IH
V
PPL
X X HIGH Z
Auto-select Manufacturer
Code (Note 2)
V
IL
V
IL
V
IH
V
PPL
V
IL
V
ID
(Note 3)
CODE
(01h)
Auto-select Device
Code (Note 2)
V
IL
V
IL
V
IH
V
PPL
V
IH
V
ID
(Note 3)
CODE
(2Fh)
Read/Write
Read V
IL
V
IL
V
IH
V
PPH
A0 A9
D
OUT
(Note 4)
Standby (Note 5) V
IH
XXV
PPH
X X HIGH Z
Output Disable V
IL
V
IH
V
IH
V
PPH
X X HIGH Z
Write V
IL
V
IH
V
IL
V
PPH
A0 A9
D
IN
(Note 6)
