M29F400BT, M29F400BB
BUS OPERATIONS
mand Interface on the rising edge of Chip Enable
or Write Enable, whichever occurs first. Output En-
There are five standard bus operations that control
the device. These are Bus Read, Bus Write, Out-
put Disable, Standby and Automatic Standby. See
Tables 5 and 6, Bus Operations, for a summary.
Typically glitches of less than 5ns on Chip Enable
or Write Enable are ignored by the memory and do
not affect bus operations.
able must remain High, V , during the whole Bus
IH
Write operation. See Figures 9 and 10, Write AC
Waveforms, and Tables 15 and 16, Write AC
Characteristics, for details of the timing require-
ments.
Output Disable. The Data Inputs/Outputs are in
the high impedance state when Output Enable is
Bus Read. Bus Read operations read from the
memory cells, or specific registers in the Com-
mand Interface. A valid Bus Read operation in-
volves setting the desired address on the Address
High, V .
IH
Standby. When Chip Enable is High, V , the
IH
Data Inputs/Outputs pins are placed in the high-
impedance state and the Supply Current is re-
duced to the Standby level.
Inputs, applying a Low signal, V , to Chip Enable
IL
and Output Enable and keeping Write Enable
High, V . The Data Inputs/Outputs will output the
IH
When Chip Enable is at V the Supply Current is
IH
value, see Figure 8, Read Mode AC Waveforms,
and Table 14, Read AC Characteristics, for details
of when the output becomes valid.
reduced to the TTL Standby Supply Current, I
.
CC2
To further reduce the Supply Current to the CMOS
Standby Supply Current, I , Chip Enable should
CC3
Bus Write. Bus Write operations write to the
Command Interface. A valid Bus Write operation
begins by setting the desired address on the Ad-
dress Inputs. The Address Inputs are latched by
the Command Interface on the falling edge of Chip
Enable or Write Enable, whichever occurs last.
The Data Inputs/Outputs are latched by the Com-
be held within V
levels see Table 13, DC Characteristics.
During program or erase operations the memory
will continue to use the Program/Erase Supply
± 0.2V. For Standby current
CC
Current, I
, for Program or Erase operations un-
CC4
til the operation completes.
Table 5. Bus Operations, BYTE = V
IL
Data Inputs/Outputs
Address Inputs
DQ15A–1, A0-A17
Operation
E
G
W
DQ14-DQ8
Hi-Z
DQ7-DQ0
Data Output
Data Input
Hi-Z
V
IL
V
V
IH
Bus Read
Cell Address
IL
IH
IH
V
IL
V
V
V
V
Bus Write
Command Address
Hi-Z
IL
Output Disable
Standby
X
X
Hi-Z
IH
V
X
X
X
Hi-Z
Hi-Z
IH
A0 = V , A1 = V , A9 = V ,
Read Manufacturer
Code
IL
IL
ID
V
V
V
V
V
Hi-Z
Hi-Z
20h
IL
IL
IL
IL
IH
IH
Others V or V
IL
IH
A0 = V , A1 = V , A9 = V ,
D5h (M29F400BT)
D6h (M29F400BB)
IH
IL
ID
V
Read Device Code
Others V or V
IL
IH
Note: X = V or V
.
IH
IL
Table 6. Bus Operations, BYTE = V
IH
Address Inputs
A0-A17
Data Inputs/Outputs
Operation
Bus Read
E
G
W
DQ15A–1, DQ14-DQ0
Data Output
Data Input
Hi-Z
V
IL
V
V
Cell Address
IL
IH
IH
IH
V
IL
V
V
V
V
Bus Write
Command Address
IL
Output Disable
Standby
X
X
X
IH
V
X
X
Hi-Z
IH
A0 = V , A1 = V , A9 = V ,
Read Manufacturer
Code
IL
IL
ID
V
V
V
V
V
0020h
IL
IL
IL
IL
IH
IH
Others V or V
IL
IH
A0 = V , A1 = V , A9 = V ,
00D5h (M29F400BT)
00D6h (M29F400BB)
IH
IL
ID
V
Read Device Code
Others V or V
IL
IH
Note: X = V or V
.
IH
IL
5/22
STMICROELECTRONICS [ ST ]
