HY29F400
Electronic ID Mode Operation
The Electronic ID mode provides manufacturer and
device identification and sector protection verifi-
cation through identifier codes output on DQ[7:0]
or DQ[15:0]. This mode is intended primarily for
programming equipment to automatically match
a device to be programmed with its correspond-
ing programming algorithm. The Electronic ID in-
formation can also be obtained by the host through
a command sequence, as described in the De-
vice Commands section.
Operation in the Electronic ID mode requires V
ID
on address pin A[9], with additional requirements
for obtaining specific data items as listed in Table
2:
n
A read cycle at address 0xXXX00 retrieves the
manufacturer code (Hynix = 0xAD).
DEVICE COMMANDS
Device operations are initiated by writing desig-
nated address and data
command sequences
into
the device. A command sequence is composed
of one, two or three of the following sub-segments:
an
unlock cycle,
a
command cycle
and a
data
cycle.
Table 4 summarizes the composition of the
valid command sequences implemented in the
HY29F400, and these sequences are fully de-
scribed in Table 5 and in the sections that follow.
Writing incorrect address and data values or writ-
ing them in the improper sequence resets the
HY29F400 to the Read mode.
Read/Reset 1, 2 Commands
The HY29F400 automatically enters the Read
mode after device power-up, after the RESET#
input is asserted and upon the completion of cer-
tain commands. Read/Reset commands are not
required to retrieve data in these cases.
A Read/Reset command must be issued in order
to read array data in the following cases:
n
If the device is in the Electronic ID mode, a
Read/Reset command must be written to re-
turn to the Read mode. If the device was in the
Erase Suspend mode when the device entered
the Electronic ID mode, writing the Read/Re-
set command returns the device to the Erase
Suspend mode.
Table 4. Composition of Command Sequences
Co mman d
Seq u en c e
Read/Reset 1
Read/Reset 2
Byte Program
Chip Erase
Sector Erase
Erase Suspend
Erase Resume
Electronic ID
Nu mb er o f B u s Cy c les
Un lo c k Co mman d
0
2
2
4
4
0
0
2
1
1
1
1
1
1
1
1
Dat a
Note 1
Note 1
1
1
1 (Note 2)
0
0
Note 3
n
A read cycle at address 0xXXX01 returns the
device code:
- HY29F400T = 0x23 in Byte mode, 0x2223 in
Word mode.
- HY29F400B = 0xAB in Byte mode, 0x22AB
in Word mode.
n
A read cycle containing a sector address (Table
1) in A[17:12] and the address 0x02 in A[7:0]
returns 0x01 if that sector is protected, or 0x00
if it is unprotected.
Notes:
1. Any number of Flash array read cycles are permitted.
2. Additional data cycles may follow. See text.
3. Any number of Electronic ID read cycles are permitted.
Note:
When in the Electronic ID bus operation mode,
the device returns to the Read mode when V
ID
is re-
moved from the A[9] pin. The Read/Reset command is
not required in this case.
n
If DQ[5] (Exceeded Time Limit) goes High dur-
ing a program or erase operation, writing the
Read/Reset command returns the sectors to
the Read mode (or to the Erase Suspend mode
if the device was in Erase Suspend).
The Read/Reset command may also be used to
abort certain command sequences:
Rev. 5.2/May 01
10
HYNIX [ HYNIX SEMICONDUCTOR ]
