CAT24C161/162 (16K), CAT24C081/082 (8K)
CAT24C041/042 (4K), CAT24C021/022 (2K)
Supervisory Circuits with I
2
C Serial CMOS EEPROM, Precision Reset Controller and Watchdog Timer
FEATURES
s
Watchdog monitors SDA for the CAT24CXX1
s
400 KHz I
2
C bus compatible
s
2.7 to 6.0 Volt operation
s
Low power CMOS technology
s
16-Byte page write buffer
s
Built-in inadvertent write protection
s
Active high or low reset
— Precision power supply voltage monitor
— 5V, 3.3V and 3V systems
— Five threshold voltage options
s
1,000,000 Program/Erase cycles
s
100 Year data retention
s
8-pin DIP or 8-pin SOIC
s
Commercial, industrial and automotive
— V
CC
lock out
— Write protect pin, WP
temperature ranges
and against brownout conditions. Five reset threshold
voltages support 5V, 3.3V and 3V systems. If power supply
voltages are out of tolerance reset signals become active,
preventing the system microcontroller, ASIC or peripherals
from operating. Reset signals become inactive typically 200
ms after the supply voltage exceeds the reset threshold
level. With both active high and low reset signals, interface
to microcontrollers and other ICs is simple. In addition, a
reset pin can be used as a debounced input for push-button
manual reset capability.
The CAT24Cxxx memory features a 16-byte page. In addition,
hardware data protection is provided by a write protect pin
WP and by a V
CC
sense circuit that prevents writes to
memory whenever V
CC
falls below the reset threshold or
until V
CC
reaches the reset threshold during power up.
DESCRIPTION
The CAT25Cxx1 is a complete memory and supervisory
solution for microcontroller-based systems. A serial
EEPROM memory (2/4/8/16K) with hardware memory
write protection, a system power supervisor with brown
out protection and a watchdog timer are integrated
together in low power CMOS technology. Memory
interface is via an I
2
C bus.
The 1.6-second watchdog circuit returns a system to a
known good state if a software or hardware glitch halts
or “hangs” the system. The CAT24Cxx1 watchdog
monitors the SDA line, making an additional PC board
trace unnecessary. The lower cost CAT24Cxx2 does
not have a watchdog timer.
The power supply monitor and reset circuit protects Available packages include an 8-pin DIP and a surface
memory and system controllers during power up/down mount, 8-pin SO package.
PIN CONFIGURATION
DC
RESET
WP
VSS
VCC
RESET
SCL
SDA
BLOCK DIAGRAM
EXTERNAL LOAD
DOUT
ACK
VCC
GND
WORD ADDRESS
BUFFERS
COLUMN
DECODERS
SENSE AMPS
SHIFT REGISTERS
CAT
24CXX1/2
SDA
START/STOP
LOGIC
XDEC
E
2
PROM
DC = Do not connect
WP
CONTROL
LOGIC
Part Dash Minimum
Number Threshold
-45
-42
-30
-28
-25
4.50
4.25
3.00
2.85
2.55
Maximum
Threshold
4.75
4.50
RESET Controller
DATA IN STORAGE
HIGH VOLTAGE/
TIMING CONTROL
STATE COUNTERS
SLAVE
ADDRESS
COMPARATORS
3.15
3.00
2.70
Only for
CAT24C161
WATCHDOG
SCL
Precision
Vcc Monitor
24C1601 BLOCK
RESET
RESET
© 2001 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
Doc No. 3000, Rev. A
CAT24CXX1/XX2
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)
........................ 100 mA
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 specifica-
tion is not implied. Exposure to any absolute maximum
rating for extended periods may affect device perfor-
mance and reliability.
PIN FUNCTIONS
Pin No. Pin Name
1
2
3
4
5
6
7
8
DC
RESET
WP
GND
SDA
SCL
RESET
V
CC
Function
Do Not Connect
Active Low Reset I/O
Write Protect
Ground
Serial Data/Address
Clock Input
Active High Reset I/O
Power Supply
RELIABILITY CHARACTERISTICS
Symbol
N
END(3)
T
DR(3)
V
ZAP(3)
I
LTH(3)(4)
Parameter
Endurance
Data Retention
ESD Susceptibility
Latch-Up
Reference Test Method
Minimum
Maximum
Units
Cycles/Byte
Years
Volts
mA
MIL-STD-883, Test Method 1033 1,000,000
MIL-STD-883, Test Method 1008
MIL-STD-883, Test Method 3015
JEDEC Standard 17
100
2000
100
D.C. OPERATING CHARACTERISTICS
V
CC
= +2.7V to +6.0V, unless otherwise specified.
Symbol
I
CC
I
SB
I
LI
I
LO
V
IL
V
IH
V
OL1
Parameter
Power Supply Current
Standby Current
Input Leakage Current
Output Leakage Current
Input Low Voltage
Input High Voltage
Output Low Voltage (SDA) I
OL
= 3 mA, V
CC
= 3.0V
Test Conditions
f
SCL
= 100 KHz
V
CC
= 3.3V
V
CC
= 5
V
IN
= G
ND
or V
CC
V
IN
= G
ND
or V
CC
-1
V
CC
X 0.7
Minimum
Typical
Maximum
3
40
50
2
10
V
CC
x 0.3
V
CC
+ 0.5
0.4
Units
mA
µA
µA
µA
µA
V
V
V
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 20 ns.
(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.
Doc. No. 3000, Rev. A
2
CAT24CXX1/XX2
CAPACITANCE
T
A
= 25˚C, f = 1.0 MHz, V
CC
= 5V
Symbol
C
I/O(1)
C
IN(1)
Test
Input/Output Capacitance (SDA)
Input Capacitance (SCL)
Conditions
V
I/O
= 0V
V
IN
= 0V
Maximum
8
6
Units
pF
pF
A.C. CHARACTERISTICS
V
CC
=2.7V to 6.0V unless otherwise specified.
Output Load is 1 TTL Gate and 100pF.
V
CC
= 2.7V - 6V
SYMBOL
F
SCL
T
I(1)
t
AA
t
BUF(1)
t
HD:STA
t
LOW
t
HIGH
t
SU:STA
t
HD:DAT
t
SU:DAT
t
R(1)
t
F(1)
t
SU:STO
t
DH
PARAMETER
Clock Frequency
Noise Suppresion Time
Constant at SCL, SDA Inputs
SLC Low to SDA Data Out
and ACK Out
Time the Bus Must be Free Before
a New Transmission Can Start
Start Condition Hold Time
Clock Low Period
Clock High Period
Start Condition Setup Time
(for a Repeated Start Condition)
Data in Hold Time
Data in Setup Time
SDA and SCL Rise Time
SDA and SCL Fall Time
Stop Condition Setup Time
Data Out Hold Time
4
100
0
50
1
300
4
4.7
4
4.7
4.7
3.5
Minimum Maximum
100
200
V
CC
= 4.5V - 5.5V
Minimum Maximum
400
200
1
1.2
0.6
1.2
0.6
0.6
0
50
0.3
300
0.6
100
Units
kHz
ns
µs
µs
µs
µs
µs
µs
ns
ns
µs
ns
µs
ns
POWER-UP TIMING
(1)(2)
Symbol
t
PUR
t
PUW
Parameter
Power-up to Read Operation
Power-up to Write Operation
Maximum
1
1
Units
ms
ms
WRITE CYCLE LIMITS
Symbol
t
WR
Parameter
Write Cycle Time
Minimum
Typical
Maximum
10
Units
ms
The write cycle time is the time from a valid stop condition of a write sequence to the end of the internal program/erase cycle. During the
write cycle, the bus interface circuits are disabled, SDA is allowed to remain high, and the device does not respond to its slave address.
NOTE:
(1) This parameter is tested initially and after a design or process change that affects the parameter.
(2) t
PUR
and t
PUW
are the delays required from the time V
CC
is stable until the specific operation can be initiated.
3
Doc No. 3000, Rev. A
CAT24CXX1/XX2
RESET CIRCUIT CHARACTERISTICS
Symbol
t
GLITCH
V
RT
V
OLRS
V
OHRS
Parameter
Glitch Reject Pulse Width
Reset Threshold Hystersis
Reset Output Low Voltage (I
OLRS
=1mA)
Reset Output High Voltage
Reset Threshold (V
CC
=5V)
(24CXXX-45)
Reset Threshold (V
CC
=5V)
(24CXXX-42)
V
TH
Reset Threshold (V
CC
=3.3V)
(24CXXX-30)
Reset Threshold (V
CC
=3.3V)
(24CXXX-28)
Reset Threshold (V
CC
=3V)
(24CXXX-25)
t
PURST
twp
t
RPD
V
RVALID
Power-Up Reset Timeout
Watchdog Period
V
TH
to RESET Output Delay
RESET Output Valid
1
4.25
3.00
2.85
2.55
130
1.6
5
4.50
3.15
3.00
2.70
270
ms
sec
µs
V
V
CC
-0.75
4.50
4.75
15
0.4
Minimum
Typical
Maximum
100
Units
ns
mV
V
V
V
Doc. No. 3000, Rev. A
4
CAT24CXX1/XX2
PIN DESCRIPTIONS
WP:
WRITE PROTECT
If the pin is tied to V
CC
the entire memory array
becomes Write Protected (READ only). When the pin
is tied to GND or left floating normal read/write
operations are allowed to the device.
SCL: SERIAL CLOCK
If there is no transition on the WDI for more than 1.6
seconds, the watchdog timer times out.
RESET/RESET RESET I/O
RESET:
RESET
These are open drain pins and can be used as reset
trigger inputs. By forcing a reset condition on the pins
the device will initiate and maintain a reset condition
for approximately 200ms. The RESET pin must be
connected through a pull-down resistor, and the
RESET
pin must be connected through a pull-up
resistor.
SDA: SERIAL DATA ADDRESS
The bidirectional serial data/address pin is used to
transfer all data into and out of the device. The SDA
pin is an open drain output and can be wire-ORed
with other open drain or open collector outputs.
remain active until V
CC
reaches the V
TH
threshold and will
continue driving the outputs for approximately 200ms (t
PURST
)
after reaching V
TH
. After the t
PURST
timeout interval, the
device will cease to drive the reset outputs. At this point the
reset outputs will be pulled up or down by their respective pull
up/down resistors. During power-down, the RESET outputs
will be active when V
CC
falls below V
TH
. The RESET outputs
will be valid so long as V
CC
is >1.0V (V
RVALID
).
The RESET pins are I/Os; therefore, the CAT24CXXX can
act as a signal conditioning circuit for an externally applied
reset. The inputs are edge triggered; that is, the RESET input
in the 24CXXX will initiate a reset timeout after detecting a
low to high transition and the RESET input in the CAT24CXXX
will initiate a reset timeout after detecting a high to low
transition.
Watchdog Timer
The Watchdog Timer provides an independent protection for
microcontrollers. During a system failure, the CAT24CXXX
will respond with a reset signal after a time-out interval of
1.63 seconds for a lack of activity. The CAT24CXX1 is
designed with the Watchdog Timer feature on the SDA input.
For the CAT24CXX1, if the microcontroller does not toggle
the SDA input pin within 1.6 sectonds, the Watchdog Timer
times out. This will generate a reset condition on reset
outputs. The Watchdog Timer is cleared by any transition on
WDI.
DEVICE OPERATION
Reset Controller Description
As long as the reset signal is asserted, the Watchdog Timer
The CAT24CXXX precision RESET controller ensures will not count and will stay cleared. The CAT24CXX2 does
correct system operation during brownout and power not have a Watchdog.
up/down conditions. It is configured with open drain
RESET outputs. During power-up, the RESET outputs
Figure 1. RESET Output Timing
t
GLITCH
V
TH
V
RVALID
V
CC
t
PURST
t
RPD
t
PURST
RESET
t
RPD
RESET
5
Doc No. 3000, Rev. A
嵌入式系统
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
