CAT25256
256-Kb SPI Serial CMOS EEPROM
FEATURES
10 MHz SPI compatible
1.8V to 5.5V supply voltage range
SPI modes (0,0) & (1,1)
64-byte page write buffer
Self-timed write cycle
Hardware and software protection
Block write protection
– Protect 1/4, 1/2 or entire EEPROM array
Low power CMOS technology
1,000,000 program/erase cycles
100 year data retention
Industrial and Extended temperature range
RoHS-compliant 8 lead PDIP, SOIC, TSSOP and
8-pad TDFN packages
8-ball Chip Scale Package (CSP)
DESCRIPTION
The CAT25256 is a 256-Kb Serial CMOS EEPROM
device internally organized as 32Kx8 bits. This
features a 64-byte page write buffer and supports the
Serial Peripheral Interface (SPI) protocol. The device
¯¯
is enabled through a Chip Select (CS) input. In
addition, the required bus signals are clock input
(SCK), data input (SI) and data output (SO) lines. The
¯¯¯¯¯ input may be used to pause any serial
HOLD
communication with the CAT25256 device. The
device features software and hardware write protec–
tion, including partial as well as full array protection.
PIN CONFIGURATION
PDIP (L)
SOIC (V, X)
TSSOP (Y)
TDFN (ZD2)
¯¯
CS
SO
¯¯¯
WP
V
SS
1
2
3
4
8 V
CC
¯¯¯¯¯
7 HOLD
6 SCK
5 SI
V
CC
¯¯¯¯¯
HOLD
SCK
SI
CSP-8B
(Top View)
1
2
3
4
¯¯
8 CS
7 SO
6 ¯¯¯
WP
5 V
SS
FUNCTIONAL SYMBOL
V
CC
SI
CS
WP
HOLD
SCK
CAT25256
SO
V
SS
PIN FUNCTION
Pin Name
¯¯
CS
SO
¯¯¯
WP
V
SS
SI
SCK
¯¯¯¯¯
HOLD
V
CC
Function
Chip Select
Serial Data Output
Write Protect
Ground
Serial Data Input
Serial Clock
Hold Transmission Input
Power Supply
1
Doc. No. MD-1127 Rev. A
For Ordering Information details, see page 16.
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT25256
ABSOLUTE MAXIMUM RATINGS
(1)
Parameters
Storage Temperature
Voltage on any Pin with Respect to Ground
(2)
RELIABILITY CHARACTERISTICS
(3)
Symbol
Parameter
N
END(4)
Endurance
T
DR
Data Retention
Min
1,000,000
100
Ratings
–65 to +150
–0.5 to + 6.5
Units
ºC
V
Units
Program/ Erase Cycles
Years
D.C. OPERATING CHARACTERISTICS
V
CC
= 1.8V to 5.5V, T
A
=-40°C to +85°C and V
CC
= 2.5V to +5.5V, T
A
=-40°C to +125°C, unless otherwise specified.
Symbol Parameter
I
CCR
I
CCW
Supply Current
(Read Mode)
Supply Current
(Write Mode)
Standby Current
Test Conditions
Read, V
CC
= 5.5V, SO open
Write, V
CC
= 5.5V, SO open
¯¯
V
IN
= GND or V
CC
, CS = V
CC
,
¯¯¯ = V
CC
, ¯¯¯¯¯ = V
CC
,
WP
HOLD
V
CC
= 5.5V
¯¯
V
IN
= GND or V
CC
, CS = V
CC
,
¯¯¯ = GND, ¯¯¯¯¯ = GND
WP
HOLD
V
CC
= 5.5V
V
IN
= GND or V
CC
¯¯
CS = V
CC
,
V
OUT
= GND or V
CC
10MHz / -40°C to 85°C
5MHz / -40°C to 125°C
10MHz / -40°C to 85°C
5MHz / -40°C to 125°C
T
A
= -40°C to +85°C
T
A
= -40°C to +125°C
T
A
= -40°C to +85°C
T
A
= -40°C to +125°C
Min
Max
2
2
4
4
1
3
4
5
Units
mA
mA
mA
mA
µA
µA
µA
µA
µA
µA
µA
V
V
V
V
V
V
I
SB1
I
SB2
I
L
I
LO
V
IL
V
IH
V
OL1
V
OH1
V
OL2
V
OH2
Standby Current
Input Leakage Current
Output Leakage
Current
Input Low Voltage
Input High Voltage
Output Low Voltage
Output High Voltage
Output Low Voltage
Output High Voltage
-2
T
A
= -40°C to +85°C
T
A
= -40°C to +125°C
-1
-1
-0.5
0.7V
CC
2
1
2
0.3V
CC
V
CC
+ 0.5
0.4
V
CC
> 2.5V, I
OL
= 3.0mA
V
CC
> 2.5V, I
OH
= -1.6mA
V
CC
> 1.8V, I
OL
= 150µA
V
CC
> 1.8V, I
OH
= -100µA
V
CC
- 0.2V
V
CC
- 0.8V
0.2
PIN CAPACITANCE
(3)
T
A
= 25˚C, f = 1.0MHz, V
CC
= +5.0V
Symbol
C
OUT
C
IN
Test
Output Capacitance (SO)
¯¯
Input Capacitance (CS, SCK, SI, ¯¯¯, HOLD)
WP ¯¯¯¯¯
Conditions
V
OUT
= 0V
V
IN
= 0V
Min
Typ
Max
8
8
Units
pF
pF
Notes:
(1) Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions outside of those listed in the operational sections of this
specification is not implied. Exposure to any absolute maximum rating for extended periods may affect device performance and reliability.
(2) The DC input voltage on any pin should not be lower than -0.5V or higher than V
CC
+ 0.5V. During transitions, the voltage on any pin may
undershoot to no less than -1.5V or overshoot to no more than V
CC
+ 1.5V, for periods of less than 20ns.
(3) These parameters are tested initially and after a design or process change that affects the parameter according to appropriate AEC-Q100
and JEDEC test methods.
(4) Page Mode, V
CC
= 5V, 25°C
Doc. No. MD-1127 Rev. A
2
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT25256
A.C. CHARACTERISTICS
T
A
= -40°C to +85°C (Industrial) and T
A
= -40°C to +125°C (Extended).
(1)
V
CC
= 1.8V-5.5V / -40°C to +85°C
V
CC
= 2.5V-5.5V / -40°C to +125°C
Symbol
f
SCK
t
SU
t
H
t
WH
t
WL
t
LZ
t
RI(2)
t
FI(2)
t
HD
t
CD
t
V
t
HO
t
DIS
t
HZ
t
CS
t
CSS
t
CSH
t
WPS
t
WPH
t
WC(4)
Parameter
Clock Frequency
Data Setup Time
Data Hold Time
SCK High Time
SCK Low Time
¯¯¯¯¯
HOLD to Output Low Z
Input Rise Time
Input Fall Time
¯¯¯¯¯
HOLD Setup Time
¯¯¯¯¯ Hold Time
HOLD
Output Valid from Clock Low
Output Hold Time
Output Disable Time
¯¯¯¯¯ to Output High Z
HOLD
¯¯
CS High Time
¯¯
CS Setup Time
¯¯
CS Hold Time
¯¯¯ Setup Time
WP
¯¯¯ Hold Time
WP
Write Cycle Time
50
50
50
10
10
5
0
50
100
15
15
15
10
10
5
0
10
75
0
20
25
Min.
DC
30
30
75
75
50
2
2
0
10
40
Max.
5
V
CC
= 2.5V-5.5V
-40°C to +85°C
Min.
DC
20
20
40
40
25
2
2
Max.
10
Units
MHz
ns
ns
ns
ns
ns
µs
µs
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ms
Power-Up Timing
(2)(3)
Symbol
t
PUR
t
PUW
Notes:
(1) AC Test Conditions:
Input Pulse Voltages: 0.3V
CC
to 0.7V
CC
Input rise and fall times:
≤
10ns
Input and output reference voltages: 0.5V
CC
Output load: current source I
OL max
/I
OH max
; C
L
= 50pF
(2) This parameter is tested initially and after a design or process change that affects the parameter.
(3) t
PUR
and t
PUW
are the delays required from the time V
CC
is stable until the specified operation can be initiated.
¯¯
(4) t
WC
is the time from the rising edge of CS after a valid write sequence to the end of the internal write cycle.
Parameter
Power-up to Read Operation
Power-up to Write Operation
Max.
1
1
Units
ms
ms
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
3
Doc. No. MD-1127 Rev. A
CAT25256
PIN DESCRIPTION
SI:
The serial data input pin accepts op-codes,
addresses and data. In SPI modes (0,0) and (1,1)
input data is latched on the rising edge of the SCK
clock input.
SO:
The serial data output pin is used to transfer data
out of the device. In SPI modes (0,0) and (1,1) data is
shifted out on the falling edge of the SCK clock.
SCK:
The serial clock input pin accepts the clock
provided by the host and used for synchronizing
communication between host and CAT25256.
¯¯
CS:
The chip select input pin is used to
¯¯
enable/disable the CAT25256. When CS is high, the
SO output is tri-stated (high impedance) and the
device is in Standby Mode (unless an internal write
operation is in progress).
Every communication
session between host and CAT25256 must be
preceded by a high to low transition and concluded
¯¯
with a low to high transition of the CS input.
¯¯¯:
The write protect input pin will allow all write
WP
operations to the device when held high. When ¯¯¯
WP
pin is tied low and the WPEN bit in the Status
Register (refer to Status Register description, later in
this Data Sheet) is set to “1”, writing to the Status
Register is disabled.
¯¯¯¯¯
¯¯¯¯¯
HOLD:
The HOLD input pin is used to pause trans–
mission between host and CAT25256, without
having to retransmit the entire sequence at a later
¯¯¯¯¯
time. To pause, HOLD must be taken low and to
resume it must be taken back high, with the SCK
input low during both transitions. When not used for
pausing, it is recommended the ¯¯¯¯¯ input to be
HOLD
tied to V
CC
, either directly or through a resistor.
Figure 1. Synchronous Data Timing
V
IH
t
CS
FUNCTIONAL DESCRIPTION
The CAT25256 device supports the Serial Peripheral
Interface (SPI) bus protocol, modes (0,0) and (1,1). The
device contains an 8-bit instruction register. The
instruction set and associated op-codes are listed in
Table 1.
Reading data stored in the CAT25256 is accomplished
by simply providing the READ command and an
address. Writing to the CAT25256, in addition to a
WRITE command, address and data, also requires
enabling the device for writing by first setting certain bits
in a Status Register, as will be explained later.
¯¯
After a high to low transition on the CS input pin, the
CAT25256 will accept any one of the six instruction op-
codes listed in Table 1 and will ignore all other possible
8-bit combinations. The communication protocol follows
the timing from Figure 1.
Table 1: Instruction Set
Instruction
WREN
WRDI
RDSR
WRSR
READ
WRITE
Opcode
0000 0110
0000 0100
0000 0101
0000 0001
0000 0011
0000 0010
Operation
Enable Write Operations
Disable Write Operations
Read Status Register
Write Status Register
Read Data from Memory
Write Data to Memory
CS
V
IL
V
IH
V
IL
V
IH
t
SU
t
CSS
t
CSH
SCK
t
WH
t
H
t
WL
SI
VALID IN
t
RI
tFI
VIL
t
V
t
HO
t
DIS
HI-Z
SO
V
OH
V
OL
HI-Z
Note:
Dashed Line = mode (1, 1) - - - - - -
Doc. No. MD-1127 Rev. A
4
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CAT25256
STATUS REGISTER
The Status Register, as shown in Table 2, contains a
number of status and control bits.
The ¯¯¯¯ (Ready) bit indicates whether the device is
RDY
busy with a write operation. This bit is automatically
set to 1 during an internal write cycle, and reset to 0
when the device is ready to accept commands. For
the host, this bit is read only.
The WEL (Write Enable Latch) bit is set/reset by the
WREN/WRDI commands. When set to 1, the device is
in a Write Enable state and when set to 0, the device
is in a Write Disable state.
The BP0 and BP1 (Block Protect) bits determine
which blocks are currently write protected. They are
set by the user with the WRSR command and are
Table 2. Status Register
7
WPEN
6
0
5
0
4
0
3
BP1
2
BP0
1
WEL
0
¯¯¯¯
RDY
non-volatile. The user is allowed to protect a quarter,
one half or the entire memory, by setting these bits
according to Table 3. The protected blocks then
become read-only.
The WPEN (Write Protect Enable) bit acts as an
enable for the ¯¯¯ pin. Hardware write protection is
WP
enabled when the ¯¯¯ pin is low and the WPEN bit
WP
is 1. This condition prevents writing to the status
register and to the block protected sections of
memory. While hardware write protection is active,
only the non-block protected memory can be written.
Hardware write protection is disabled when the ¯¯¯
WP
pin is high or the WPEN bit is 0. The WPEN bit, ¯¯¯
WP
pin and WEL bit combine to either permit or inhibit
Write operations, as detailed in Table 4.
Table 3. Block Protection Bits
Status Register Bits
BP1
0
0
1
1
BP0
0
1
0
1
Array Address Protected
None
6000-7FFF
4000-7FFF
0000-7FFF
Protection
No Protection
Quarter Array Protection
Half Array Protection
Full Array Protection
Table 4. Write Protect Conditions
WPEN
0
0
1
1
X
X
¯¯¯
WP
X
X
Low
Low
High
High
WEL
0
1
0
1
0
1
Protected
Blocks
Protected
Protected
Protected
Protected
Protected
Protected
Unprotected
Blocks
Protected
Writable
Protected
Writable
Protected
Writable
Status
Register
Protected
Writable
Protected
Protected
Protected
Writable
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
5
Doc. No. MD-1127 Rev. A
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