Preliminary
CAT35C804A
4K-Bit Secure Access Serial E
2
PROM
FEATURES
s
Single 5V Supply
s
Password READ/WRITE Protection: 1 to 8 Bytes
s
Memory Pointer WRITE Protection
s
Sequential READ Operation
s
256 x16 or 512 x 8 Selectable Serial Memory
s
UART Compatible Asynchronous Protocol
s
100,000 Program/Erase Cycles
s
Commercial, Industrial and Automotive
Temperature Ranges
s
I/O Speed: 9600 Baud
–Clock Frequency: 4.9152 MHz Xtal
s
Low Power Consumption:
–Active: 3 mA
–Standby: 250
µ
A
s
100 Year Data Retention
DESCRIPTION
The CAT35C804A is a 4K-bit Serial E
2
PROM that safe-
guards stored data from unauthorized access by use of
a user selectable (1 to 8 byte) access code and a
movable memory pointer. Two operating modes provide
unprotected and password-protected operation allow-
ing the user to configure the device as anything from a
ROM to a fully protected no-access memory. The
CAT35C804A uses a UART compatible asynchronous
protocol and has a Sequential Read feature where data
can be sequentially clocked out of the memory array.
The device is available in 8-pin DIP or 16-pin SOIC
packages.
PIN CONFIGURATION
DIP Package (P)
CS
CLK
DI
DO
1
2
3
4
8
7
6
5
VCC
PE
ERR
GND
BLOCK DIAGRAM
SOIC Package (J)
NC
NC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
NC
NC
VCC
PE
ERR
GND
NC
NC
5074 FHD F01
CS
CLK
DI
DO
NC
NC
VCC
GND
-
64-BIT ACCESS CODE
&
CONTROL BLOCK
SERIAL
COMMUNI-
CATION
BLOCK
PIN FUNCTIONS
Pin Name
CS
DO
(1)
CLK
DI
(1)
PE
ERR
V
CC
GND
Function
Chip Select
Serial Data Output
Clock Input
Serial Data Input
Parity Enable
Error Indication Pin
+5V Power Supply
Ground
DO
CLK
PE
CS
DI
4K-BIT EEPROM
ARRAY
R/W
BUFFER
ADDRESS
DECODER
INSTRUCTION
REGISTER
ERR
INSTRUCTION
DECODER
ADDRESS
REGISTER
STATUS
REGISTER
MEMORY
POINTER
Note:
(1) DI, DO may be tied together to form a common I/O.
35C804 F02
© 1998 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1
Doc. No. 25043-00 2/98
CAT35C804A
Preliminary
ABSOLUTE MAXIMUM RATINGS*
Temperature Under Bias ................. –55°C to +125°C
Storage Temperature ....................... –65°C to +150°C
Voltage on Any Pin with
Respect to Ground
(1)
........... –2.0V to +V
CC
+ 2.0V
V
CC
with Respect to Ground ............... –2.0V to +7.0V
Package Power Dissipation
Capability (T
a
= 25°C) ................................... 1.0W
Lead Soldering Temperature (10 secs) ............ 300°C
Output Short Circuit Current
(2)
........................ 100mA
RELIABILITY CHARACTERISTICS
Symbol
N
END(3)
T
DR(3)
V
ZAP(3)
I
LTH(3)(4)
Parameter
Endurance
Data Retention
ESD Susceptibility
Latch-up
Min.
100,000
100
2000
100
Max.
*COMMENT
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.
Units
Cycles/Byte
Years
Volts
mA
Reference Test Method
MIL-STD-883, Test Method 1033
MIL-STD-883, Test Method 1008
MIL-STD-883, Test Method 3015
JEDEC Standard 17
D.C. CHARACTERISTICS
V
CC
= +5V
±10%,unless
otherwise specified.
Limits
Symbol
I
CC
I
SB
V
IL
V
IH
V
OL
V
OH
I
LI(5)
I
LO
Parameter
Power Supply Current
(Operating)
Power Supply Current
(Standby)
Input Low Voltage
Input High Voltage
Output Low Voltage
Output High Voltage
Input Leakage Current
Output Leakage Current
2.4
2
10
–0.1
2
0.4
Min.
Typ.
Max.
3
250
0.8
Units
mA
µA
V
V
V
V
µA
µA
I
OL
= 2.1mA
I
OH
= –400µA
V
IN
= 5.5V
V
OUT
= 5.5V, CS = 0V
Test Conditions
V
CC
= 5.5V, CS = V
CC
DO is Unloaded.
V
CC
= 5.5V, CS = 0V
DI = 0V, CLK = 0V
Note:
(1) The minimum DC input voltage is –0.5V. During transitions, inputs may undershoot to –2.0V for periods of less than 20 ns. Maximum DC
voltage on output pins is V
CC
+0.5V, which may overshoot to V
CC
+ 2.0V for periods of less than 20ns.
(2) Output shorted for no more than one second. No more than one output shorted at a time.
(3) This parameter is tested initially and after a design or process change that affects the parameter.
(4) Latch-up protection is provided for stresses up to 100 mA on address and data pins from –1V to V
CC
+1V.
(5) PE pin test conditions: V
IH
< V
IN
< V
IL
Doc. No. 25043-00 2/98
2
Preliminary
A.C. CHARACTERISTICS
V
CC
= +5V
±10%,unless
otherwise specified.
Limits
Symbol
t
CSH
t
D
t
PD
t
HZ(1) (2)
t
EW
t
CSL
t
SV
t
VCCS(1)
f
CLK
Parameter
CS Hold Time
CLK to DO Delay
CLK to DO Delay
CLK to DO High-Z Delay
Program/Erase Pulse Width
CS Low Pulse Width
ERR
Output Delay
V
CC
to CS Setup Time
Clock Frequency
5
DC
4.9152
100
150
Min.
0
104
150
50
12
Typ.
Max.
Units
ns
µs
ns
ns
ms
ns
ns
µs
MHz
CAT35C804A
Test Conditions
C
L
= 100pF
V
IN
= V
IH
or V
IL
V
OUT
= V
OH
or V
OL
C
L
= 100pF
C
L
= 100pF
Note:
(1) This parameter is tested initially and after a design or process change that affects the parameter.
(2) t
HZ
is measured from the falling edge of the clock to the time when the output is no longer driven.
3
Doc. No. 25043-00 2/98
CAT35C804A
Preliminary
divided into a read-only area and a non-access area.
Figure 2 illlustrates this partitioning of the memory array.
PASSWORD PROTECTION
The CAT35C804A is a 4K-bit E
2
PROM that features a
password protection scheme to prevent unauthorized
access to the information stored in the device. It contains
an access code register which stores one to eight bytes
of access code along with the length of that access code.
Additionally, a memory pointer register stores the ad-
dress that partitions the memory into protected and
unprotected areas. As shipped from the factory, the
device is unprogrammed and unprotected. The length of
the access code is equal to zero and the memory pointer
register points to location zero. Every byte of the device
is fully accessible without an access code. Setting a
password and moving the memory pointer register to
cover all or part of the memory secures the device. Once
secured, the memory is divided into a read/write area
and a read-only area with the entry of a valid access
code. If no access code is entered, the memory is
Figure 1. A.C. Timing
VCC
tVCCS
CS
WRITE PROTECTION
Another feature of the CAT35C804A is WRITE-protec-
tion without the use of an access code. If the memory
pointer register is set to cover all or part of the memory,
without setting the access code register, the device may
be divided into an area which allows full access, and an
area which allows READ-only access. To write into the
READ-only area, the user can override the memory
pointer register for every WRITE instruction or he can
simply move the address in the memory pointer register
to uncover this area, and then write into the memory.
This mechanism prevents inadvertent overwriting of
important data in the memory without the use of an
access code. Figure 3 illustrates this partitioning of the
memory array.
CLK
tD
DI
START BIT
tD
STOP BIT
tHZ
DO
HIGH-Z
HIGH-Z
35C804 F03
MARK
DATA TIMING
(1)
PARITY
BIT
START
BIT
BIT TIME
104
µs
CHARACTER TIME @ 9600 BAUD
Note:
(1) If PE pin = 1.
Doc. No. 25043-00 2/98
4
STOP
BIT
SPACE
D0
D1
D2
D3
D4
D5
D6
D7
Preliminary
CAT35C804A
READ SEQUENTIAL
To allow for convenient reading of blocks of contiguous
data, the device has a READ SEQUENTIAL instruction
which accepts a starting address of the block and
continuously outputs data of subsequent addresses
until the end of memory, or until Chip Select goes LOW.
The CAT35C804A communicates with external devices
via an asynchronous serial communication protocol.
The data transmission may be a continuous stream of
data or it can be packed by pulsing Chip Select LOW in
between each packet of information. (Except for the
SEQUENTIAL READ instruction where Chip Select
must be held high).
PIN DESCRIPTIONS
CS
Chip Select is a TTL compatible input which, when set
HIGH, allows normal operation of the device. Any time
Chip Select is set LOW, it resets the device, terminating
all I/O communication, and puts the output in a high
impedance state. CS is used to reset the device if an
error condition exists or to put the device in a power-
down mode to minimize power consumption. It may also
be used to frame data transmission in applications
where the clock and data input have to be ignored from
time to time. Although CS resets the device, it does not
change the program/erase or the access-enable status,
nor does it terminate a programming cycle once it has
started. The program/erase and access-enable opera-
tions, once enabled, will remain enabled until specific
disabling instructions are sent or until power is removed.
Figure 2. Secure Mode
ACCESS REGISTER:
ACCESS CODE LENGTH:
MEMORY POINTER:
ACCESS CODE (1–8 BYTES)
1 TO 8
a…a
255 (x16)
511 (x8)
READ-ONLY
ACCESS
POINTER
REGISTER
ADDRESS
IN MEMORY
a…a
PASSWORD-ONLY
ACCESS
0
5074 FHD F04
Figure 3. Unprotected Mode
(1)
ACCESS REGISTER:
ACCESS CODE LENGTH:
MEMORY POINTER:
x…x
0
a…a
255 (x16)
511 (x8)
READ/WRITE/ERASE
ACCESS
POINTER
REGISTER
ADDRESS
IN MEMORY
a…a
READ-ONLY
ACCESS
0
5074 FHD F05
Note:
(1) x = DON’T CARE; a = ADDRESS BIT.
5
Doc. No. 25043-00 2/98
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