m27w256 STMicroelectronics, m27w256 Datasheet - Page 8

• Manufacturer Part Number: m27w256
• Description: 256 Kbit 32kb X 8 Low Voltage Uv Eprom And Otp Eprom
• Manufacturer: STMicroelectronics

Device description
2
Note:
2.1
2.2
2.3
8/23
Read mode
Standby mode
Two-line output control
Device description
Table 2
All inputs are TTL levels except for V
Table 2.
X = V
The M27W256 has two control functions, both of which must be logically active in order to
obtain data at the outputs. Chip Enable (E) is the power control and should be used for
device selection. Output Enable (G) is the output control and should be used to gate data to
the output pins, independent of device selection. Assuming that the addresses are stable,
the address access time (t
available at the output after delay of t
been low and the addresses have been stable for at least t
The M27W256 has a standby mode which reduces the supply current from 10mA to 10µA
with low voltage operation V
The M27W256 is placed in the standby mode by applying a CMOS high signal to the E
input. When in the standby mode, the outputs are in a high impedance state, independent of
the G input.
Because EPROMs are usually used in larger memory arrays, this product features a 2-line
control function which accommodates the use of multiple memory connection. The two line
control function allows:
For the most efficient use of these two control lines, E should be decoded and used as the
primary device selecting function, while G should be made a common connection to all
Read
Output Disable
Program
Verify
Program Inhibit
Standby
Electronic Signature
the lowest possible memory power dissipation,
complete assurance that output bus contention will not occur.
IH
lists M27W256 operating modes. A single power supply is required in Read mode.
or V
Mode
IL
Operating modes
, V
ID
= 12V ± 0.5V.
V
AVQV
IL
CC
V
V
V
V
V
V
Pulse
E
IH
IH
IH
IL
IL
IL
) is equal to the delay from E to output (t
3.6V, see Read Mode DC Characteristics table for details.
PP
GLQV
and 12V on A9 for Electronic Signature.
V
V
V
V
V
V
from the falling edge of G, assuming that E has
G
X
IH
IH
IH
IL
IL
IL
V
A9
X
X
X
X
X
X
ID
AVQV
-t
GLQV
V
V
V
V
V
V
V
V
.
CC
CC
CC
CC
PP
PP
PP
PP
ELQV
). Data is
Data Out
Data Out
M27W256
Data In
Q7-Q0
Codes
Hi-Z
Hi-Z
Hi-Z