CAT25010 Datasheet, PDF (5/11 Pages) Catalyst Semiconductor – 1K/2K/4K SPI Serial CMOS EEPROM

CAT25010/20/40
clock for SPI modes (0,0 & 1,1).
SCK: Serial Clock
SCK is the serial clock pin. This pin is used to synchronize
the communication between the microcontroller and the
CAT25010/20/40. Opcodes, byte addresses, or data
present on the SI pin are latched on the rising edge of the
SCK. Data on the SO pin is updated on the falling edge
of the SCK for SPI modes (0,0 & 1,1) .
CS: Chip Select
CS is the Chip select pin. CS low enables the CAT25010/
20/40 and CS high disables the CAT25010/20/40. CS
high takes the SO output pin to high impedance and
forces the devices into a Standby Mode (unless an
internal write operation is underway) The CAT25010/
20/40 draws ZERO current in the Standby mode. A high
to low transition on CS is required prior to any sequence
being initiated. A low to high transition on CS after a valid
write sequence is what initiates an internal write cycle.
STATUS REGISTER
7
6
5
4
1
1
1
1
WP: Write Protect
WP is the Write Protect pin. The Write Protect pin will
allow normal read/write operations when held high.
When WP is tied low all write operations are inhibited.
WP held low while CS is low will interrupt a write to the
CAT25010/20/40. If the internal write cycle has already
been initiated, WP going low will have no effect on any
write operation. Figure 10 illustrates the WP timing
sequence during a write operation.
HOLD: Hold
The HOLD pin is used to pause transmission to the
CAT25010/20/40 while in the middle of a serial sequence
without having to re-transmit entire sequence at a later
time. To pause, HOLD must be brought low while SCK
is low. The SO pin is in a high impedance state during
the time the part is paused, and transitions on the SI pins
will be ignored. To resume communication, HOLD is
brought high, while SCK is low. (HOLD should be held
high any time this function is not being used.) HOLD may
be tied high directly to VCC or tied to VCC through a
resistor. Figure 9 illustrates hold timing sequence.
3
2
1
0
BP1
BP0
WEL
RDY
BLOCK PROTECTION BITS
Status Register Bits
BP1
BP0
0
0
0
1
1
0
1
1
Array Address
Protected
None
25010: 60-7F
25020: C0-FF
25040: 180-1FF
25010: 40-7F
25020: 80-FF
25040: 100-1FF
25010: 00-7F
25020: 00-FF
25040: 000-1FF
Protection
No Protection
Quarter Array Protection
Half Array Protection
Full Array Protection
5
Doc. No. 1006, Rev. L