CAT28F010
READ OPERATIONS
Read Mode
The conventional mode is entered as a regular READ
mode by driving the CE and OE pins low (with WE high),
andapplyingtherequiredhighvoltageonaddresspinA9
while all other address lines are held at VIL.
A Read operation is performed with both CE and OE low
and with WE high. VPP can be either high or low,
however, if VPP is high, the Set READ command has to
be sent before reading data (see Write Operations). The
data retrieved from the I/O pins reflects the contents of
thememorylocationcorrespondingtothestateofthe17
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.
A Read cycle from address 0000H retrieves the binary
code for the IC manufacturer on outputs I/O0 to I/O7:
CATALYST Code = 00110001 (31H)
A Read cycle from address 0001H retrieves the binary
code for the device on outputs I/O0 to I/O7.
Signature Mode
The signature mode allows the user to identify the IC
manufacturer and the type of device while the device
residesinthetargetsystem. Thismodecanbeactivated
in either of two ways; through the conventional method
of applying a high voltage (12V) to address pin A9 or by
sending an instruction to the command register (see
Write Operations).
28F010 Code = 1011 0100 (B4H)
Standby Mode
With CE at a logic-high level, the CAT28F010 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.
Figure 3. A.C. Timing for Read Operation
STANDBY
DEVICE AND
OUPUTS
DATA VALID
STANDBY
POWER DOWN
POWER UP
ADDRESS SELECTION
ENABLED
ADDRESS STABLE
ADDRESSES
CE (E)
t
(t
)
AVAV RC
t
t(
)
)
EHQZ DF
OE (G)
t
t
(t
WHGL
GHQZ DF
t
(t
)
WE (W)
GLQV OE
t
(t
)
ELQV CE
t
t(
)
AXQX OH
t
(t
)
GLQX OLZ
t
(t
)
ELQX LZ
HIGH-Z
HIGH-Z
OUTPUT VALID
DATA (I/O)
t
(t
)
AVQV ACC
28F010 F05
Doc. No. 25005-0A 2/98 F-1
8
CATALYST [ CATALYST SEMICONDUCTOR ]
