Preliminary information
®
AS29F400
Operating modes
Mode
ID read MFR code
ID read device code
Read
Standby
Output disable
Write
Enable sector protect
Sector unprotect
Verify sector protect
Temporary sector
unprotect
Hardware Reset
CE
L
L
L
H
L
L
L
L
L
X
X
OE
L
L
L
X
H
H
V
ID
V
ID
L
X
X
WE
H
H
H
X
H
L
Pulse/L
Pulse/L
H
X
X
A0
L
H
A0
X
X
A0
L
L
L
X
X
A1
L
L
A1
X
X
A1
H
H
H
X
X
A6
L
L
A6
X
X
A6
L
H
L
X
X
A9
V
ID
V
ID
A9
X
X
A9
V
ID
V
ID
V
ID
X
X
RESET
H
H
H
H
H
H
H
H
H
V
ID
L
DQ
Code
Code
D
OUT
High Z
High Z
D
IN
X
X
Code
X
High Z
L = Low (<V
IL
); H = High (>V
IH
); V
ID
= 12.0 ± 0.5V; X = don’t care; In ×16 mode, BYTE = V
IH
. In ×8 mode, BYTE = V
IL
and DQ8–14 is High Z with
DQ15 = A-1(X).
Mode definitions
Item
ID MFR code,
device code
Read mode
Description
Selected by A9 = V
ID
(11.5–12.5V), CE = OE = A1 = A6 = L, enabling outputs.
When A0 is low (V
IL
) the output data = 52h, a unique Mfr. code for Alliance Semiconductor Flash products.
When A0 is high (V
IH
), D
OUT
represents the device code for the 29F400.
Selected with CE = OE = L, WE = H. Data is valid in t
ACC
time after addresses are stable, t
CE
after CE is low
and t
OE
after OE is low.
Selected with CE = H. Part is powered down, and I
CC
reduced to <1.0 mA for TTL input levels and <100 µA
for CMOS levels. If activated during an automated on-chip algorithm, the device completes the operation
before entering standby.
Selected with CE = WE = L, OE = H. Accomplish all Flash erasure and programming through the command
register. Contents of command register serve as inputs to the internal state machine. Address latching occurs
on the falling edge of WE or CE, whichever occurs later. Data latching occurs on the rising edge WE or CE,
whichever occurs first. Filters on WE prevent spurious noise events from appearing as write commands.
Hardware protection circuitry implemented with external programming equipment causes the device to
disable program and erase operations for specified sectors.
Disables sector protection using external programming equipment.
Verifies write protection for sector. Sectors are protected from program/erase operations on commercial
programming equipment. Determine if sector protection exists in a system by writing the ID read command
sequence and reading location XXX02h, where address bits A12–17 select the defined sector addresses. A
logical 1 on DQ0 indicates a protected sector; a logical 0 indicates an unprotected sector.
Temporarily disables sector protection for in-system data changes to protected sectors. Apply +12V to RESET
to activate temporary sector unprotect mode. During temporary sector unprotect mode, program protected
sectors by selecting the appropriate sector address. All protected sectors revert to protected state on removal
of +12V from RESET.
Standby
Output disable Part remains powered up; but outputs disabled with OE pulled high.
Write
Enable
sector protect
Sector
unprotect
Verify
sector protect
Temporary
sector
unprotect
3
ALSC [ ALLIANCE SEMICONDUCTOR CORPORATION ]
