CAT28F512 CATALYST [Catalyst Semiconductor], CAT28F512 Datasheet - Page 8

• Manufacturer Part Number: CAT28F512
• Description: 512K-Bit CMOS Flash Memory
• Manufacturer: CATALYST [Catalyst Semiconductor]

CAT28F512
READ OPERATIONS
Read Mode
A Read operation is performed with both CE and OE low
and with WE high. V
however, if V
be sent before reading data (see Write Operations). The
data retrieved from the I/O pins reflects the contents of
the memory location corresponding to the state of the 16
address pins. The respective timing waveforms for the
read operation are shown in Figure 3. Refer to the AC
Read characteristics for specific timing parameters.
Signature Mode
The signature mode allows the user to identify the IC
manufacturer and the type of device while the device
resides in the target system. This mode can be activated
in either of two ways; through the conventional method
of applying a high voltage (12V) to address pin A
sending an instruction to the command register (see
Write Operations).
Figure 3. A.C. Timing for Read Operation
Doc. No. 25042-00 2/98 F-1
ADDRESSES
DATA (I/O)
WE (W)
OE (G)
CE (E)
PP
is high, the Set READ command has to
POWER UP
HIGH-Z
PP
can be either high or low,
STANDBY
ADDRESS SELECTION
t WHGL
DEVICE AND
t GLQX (t OLZ )
9
or by
t ELQX (t LZ )
t AVQV (t ACC )
ADDRESS STABLE
8
t AVAV (t RC )
The conventional mode is entered as a regular READ
mode by driving the CE and OE pins low (with WE high),
and applying the required high voltage on address pin A
while all other address lines are held at V
A Read cycle from address 0000H retrieves the binary
code for the IC manufacturer on outputs I/O
A Read cycle from address 0001H retrieves the binary
code for the device on outputs I/O
Standby Mode
With CE at a logic-high level, the CAT28F512 is placed
in a standby mode where most of the device circuitry is
disabled, thereby substantially reducing power con-
sumption. The outputs are placed in a high-impedance
state.
t GLQV (t OE )
ENABLED
OUPUTS
CATALYST Code = 00110001 (31H)
28F512 Code = 1011 1000 (B8H)
t ELQV (t CE )
DATA VALID
OUTPUT VALID
STANDBY
t AXQX (t OH )
t GHQZ (t DF )
t EHQZ (t DF )
0
to I/O
POWER DOWN
Preliminary
7
IL
.
.
HIGH-Z
0
to I/O
28F512 F06
7
:
9