Advanced
CAT24C321/322(32K), CAT24C641/642(64K)
Supervisory Circuits with I2C Serial CMOS E2PROM, Precision Reset Controller and Watchdog Timer
FEATURES
s
Watchdog Timer on SDA for 24C321/641
s
Programmable Reset Threshold
s
400 KHz I2C Bus Compatible
s
2.7 to 6 Volt Operation
s
Low Power CMOS Technology
s
32 - Byte Page Write Buffer
s
Built-in inadvertent write protection
s
Active High or Low Reset Outputs
— Precision Power Supply Voltage Monitoring
— 5V, 3.3V and 3V 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
Temperature Ranges
DESCRIPTION
The CAT24CXXX is a single chip solution to three
popular functions of EEPROM memory, precision reset
controller and watchdog timer. The 24C321/322(32K)
and 24C641/642(64K) feature a I
2
C Serial CMOS
EEPROM. Catalyst's advanced CMOS technology sub-
stantially reduces device power requirements. The
24CXXX features a 32-byte page and is available in 8-pin
DIP or 8-pin SOIC packages.
The reset function of the 24CXXX protects the system
during brown out and power up/down conditions. During
system failure the watchdog timer feature protects the
microcontroller with a reset signal. 24CXXX features
active low reset on pin 2 and active high reset on pin 7.
24C321/641 features watchdog timer on the SDA line.
24C322/642 does not feature the watchdog timer func-
tion.
PIN CONFIGURATION
24C321/322*
24C641/642*
DC
RESET
WP
VSS
VCC
RESET
SCL
SDA
BLOCK DIAGRAM
EXTERNAL LOAD
DOUT
ACK
VCC
VSS
WORD ADDRESS
BUFFERS
COLUMN
DECODERS
SENSE AMPS
SHIFT REGISTERS
*All products offered in P and J packages
SDA
START/STOP
LOGIC
PIN FUNCITONS
Pin Name
SDA
RESET/RESET
SCL
Vcc
DC
V
SS
WP
Function
WP
XDEC
CONTROL
LOGIC
E
2
PROM
Serial Data/Address
Reset I/O
Clock Input
Power Supply
Do not Connect
Ground
Write Protect
Only for
24C321/641
DATA IN STORAGE
HIGH VOLTAGE/
TIMING CONTROL
RESET Controller
WATCHDOG
STATE COUNTERS
SLAVE
ADDRESS
COMPARATORS
SCL
High
Precision
Vcc Monitor
RESET/RESET
24C1601 BLOCK
© 1998 by Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
9-1
Doc. No. 25083-00 12/98
CAT24C321/322/641/642
Advanced
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
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 specifica-
tion is not implied. Exposure to any absolute maximum
rating for extended periods may affect device perfor-
mance and reliability.
V
CC
with Respect to Ground..................–2.0V to +7.0V
Package Power Dissipation
Capability (Ta = 25°C)1.0W.................................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.
1,000,000
100
2000
100
Max.
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. OPERATING CHARACTERISTICS
V
CC
= +2.7V to +6.0V, unless otherwise specified.
Symbol
I
CC
Isb
Parameter
Power Supply Current
Standby Current
Min.
Limits
Typ. Max.
3
40
50
Units
mA
µA
µA
µA
µA
V
V
V
Test Conditions
f
SCL
= 100 KHz
Vcc=3.3V
Vcc=5
V
IN
=G
ND
or V
CC
V
IN
=G
ND
or V
CC
I
LI
I
LO
V
IL
V
IH
V
OL
Input Leakage Current
Output Leakage Current
Input Low Voltage
Input High Voltage
Output Low Voltage (SDA)
–1
V
CC
x 0.7
2
10
V
CC
x 0.3
V
CC
+ 0.5
0.4
I
OL
= 3 mA ,V
CC
=3.0V
CAPACITANCE
T
A
= 25°C, f = 1.0 MHz, V
CC
= 5V
Symbol
C
I/O(3)
C
IN(3)
Test
Input/Output Capacitance (SDA)
Input Capacitance (SCL)
Max.
8
6
Units
pF
pF
Conditions
V
I/O
= 0V
V
IN
= 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.
Doc. No. 25083-00 12/98
2
Advanced
A.C. CHARACTERISTICS
V
CC
=2.7V to 6.0V unless otherwise specified.
Output Load is 1 TTL Gate and 100pF
CAT24C321/322/641/642
Read & Write Cycle Limits
Symbol
Parameter
V
CC
=2.7V - 6V
Min.
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
Clock Frequency
Noise Suppression Time
Constant at SCL, SDA Inputs
SCL 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
4.7
4
4.7
4
4.7
0
50
1
300
0.6
100
Max.
100
200
3.5
1.2
0.6
1.2
0.6
0.6
0
50
0.3
300
V
CC
=4.5V - 5.5V
Min.
Max.
400
200
1
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
Max.
1
1
Units
ms
ms
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 specified operation can be initiated.
Write Cycle Limits
Symbol
t
WR
Parameter
Write Cycle Time
Min.
Typ.
Max
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.
3
Doc. No. 25083-00 12/98
CAT24C321/322/641/642
Advanced
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 (Vcc=5V)
(24CXXX-45)
Reset Threshold (Vcc=5V)
(24CXXX-42)
Min.
Max.
100
Units
ns
mV
15
0.4
Vcc-0.75
4.50
4.25
3.00
2.85
2.55
130
4.75
4.50
V
V
V
3.15
3.00
2.70
270
5
1
ms
µs
V
V
TH
Reset Threshold (Vcc=3.3V)
(24CXXX-30)
Reset Threshold (Vcc=3.3V)
(24CXXX-28)
Reset Threshold (Vcc=3V)
(24CXXX-25)
t
PURST
t
RPD
Power-Up Reset Timeout
V
TH
to RESET Output Delay
RESET Output Valid
V
RVALID
Doc. No. 25083-00 12/98
4
Advanced
CAT24C321/322/641/642
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 V
SS
or left floating normal read/write operations are allowed
to the device.
SCL:
SERIAL CLOCK
The serial clock input clocks all data transferred into or
out of the device.
RESET
RESET/RESET
RESET I/O
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. RESET pin must be connected
through a pull-down and
RESET
pin must be connected
through a pull-up device.
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. In the 24C321/
641, the SDA line is also used as the Watchdog Timer
Monitor.
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
reset outputs. At this point the reset outputs will be
pulled up or down by their respective pull up/pull down
devices. During power-down, the RESET outputs will
begin driving 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 level triggered; that is, the
RESET input in the 24CXXX will initiate a reset timeout
after detecting a high and the
RESET
input in the
24CXXX will initiate a reset timeout after detecting a low.
Watchdog Timer
The Watchdog Timer provides an independent protec-
tion for microcontrollers. During a system failure, the
CAT24C321/641 will respond with a reset signal after a
time-out interval of 1.6 seconds for lack of activity.
24CXX1 is designed with the Watchdog Timer feature
on the SDA input. For the 24C321/641, if the
microcontroller does not toggle the SDA input pin within
1.6 seconds the Watchdog Timer times out. This will
generate a reset condition on reset outputs. The Watch-
dog Timer is cleared by any transition on SDA.
As long as the reset signal is asserted, the Watchdog
Timer will not count and will stay cleared. 24C322/642
does not feature the Watchdog Timer function.
DEVICE OPERATION
Reset Controller Description
The CAT24CXXX provides a precision RESET control-
ler that ensures correct system operation during brown-
out and power-up/down conditions. It is configured
with open drain RESET outputs. During power-up, the
RESET outputs remain active until V
CC
reaches the
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. 25083-00 12/98
电源技术
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
