CAT1026, CAT1027
Dual Voltage Supervisory Circuits with
I²C Serial 2k-bit CMOS EEPROM
FEATURES
Precision V
CC
Power Supply Voltage Monitor
—
5 V, 3.3 V and 3 V systems
—
Five threshold voltage options
Additional voltage monitoring
—
Externally adjustable down to 1.25 V
Watchdog timer (CAT1027 only)
Active High or Low Reset
—
Valid reset guaranteed at V
CC
= 1 V
400 kHz I
2
C Bus
2.7 V to 5.5 V Operation
Low power CMOS technology
16-Byte Page Write Buffer
Built-in inadvertent write protection
1,000,000 Program/Erase cycles
Manual Reset capability
100 year data retention
Industrial and extended temperature ranges
8-pin DIP, SOIC, TSSOP, MSOP or TDFN
(3 x 3 mm foot-print) packages
—
TDFN max height is 0.8 mm
For Ordering Information details, see page 19.
The CAT1027 is designed with a 1.6 second
watchdog timer circuit that resets a system to a known
state if software or a hardware glitch halts or “hangs”
the system. The CAT1027 features a watchdog timer
interrupt input, WDI.
The on-chip 2k-bit EEPROM memory features a 16-byte
page. In addition, hardware data protection is provided
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.
Available packages include 8-pin DIP and surface
mount, 8-pin SO, 8-pin TSSOP, 8-pin TDFN and 8-pin
MSOP packages. The TDFN package thickness is
0.8 mm maximum. TDFN footprint is 3 x 3 mm.
supply monitor and reset circuit protects memory and
systems controllers during power up/down and
against brownout conditions. If power supply voltages
are out of tolerance reset signals become active
preventing the system microcontroller, ASIC, or
peripherals from operating.
The CAT1026 features two open drain reset outputs:
¯¯¯¯¯¯
one (RESET) drives high and the other (RESET)
drives low whenever V
CC
falls below the threshold.
Reset outputs become inactive typically 200ms after
the supply voltage exceeds the reset threshold value.
With both active high and low reset signals, interface
to microcontrollers and other ICs is simple. CAT1027
¯¯¯¯¯¯
¯¯¯¯¯¯
has only a RESET output. In addition, the RESET pin
can be used as an input for push-button manual reset
capability.
The CAT1026 and CAT1027 provide an auxiliary
voltage sensor input, V
SENSE
, which is used to monitor a
second system supply. The auxiliary high impedance
comparator drives the open drain output, V
LOW
,
whenever the sense voltage is below 1.25 V threshold.
DESCRIPTION
The CAT1026 and CAT1027 are complete memory
and supervisory solutions for microcontroller-based
systems. A 2k-bit serial EEPROM memory and a
system power supervisor with brown-out protection
are integrated together in low power CMOS techno–
logy. Memory interface is via a 400 kHz I
2
C bus.
The CAT1026 and CAT1027 provide a precision V
CC
sense circuit with five reset threshold voltage options
that support 5 V, 3.3 V and 3 V systems. The power
© 2009 SCILLC. All rights reserved.
Characteristics subject to change without notice
1
Doc. No. MD-3010 Rev. P
CAT1026, CAT1027
BLOCK DIAGRAM
EXTERNA LOAD
L
DOUT
ACK
VCC
VSS
WORDADDRESS
BUFFERS
START/STOP
LOGIC
2kbit
EEPROM
COLUMN
DECODERS
SENSEAMPS
SHIFT REGISTERS
RESET THRESHOLD OPTION
Part Dash
Number
-45
-42
-30
-28
XDEC
CONTR
OL
LOGIC
Minimum
Threshold
4.50
4.25
3.00
2.85
2.55
Maximum
Threshold
4.75
4.50
3.15
3.00
2.70
SDA
-25
DATA IN STORAGE
VCC Monitor
VCC
HIGHVOLTAGE/
TIMING CONTR
OL
STATE COUNTERS
SCL
+
VREF
-
RESET
Controller
WDI
(CAT1027)
SLAVE
ADDRESS
COMPARATORS
AuxiliaryVoltage Monitor
VSENSE
VREF
+
-
RESET
RESET
(CAT1026)
VLOW
PIN CONFIGURATION
DIP Package (L)
SOIC Package (W)
TSSOP Package (Y)
MSOP Package (Z)
V
LOW
¯¯¯¯¯¯
RESET
V
SENSE
V
SS
V
LOW
¯¯¯¯¯¯
RESET
V
SENSE
V
SS
1
2
CAT1026
3
4
1
2
CAT1027
3
4
6
5
SCL
SDA
6
5
8
7
SCL
SDA
V
CC
WDI
SCL 6
SDA 5
V
CC
8
WDI 7
CAT1027
SCL 6
SDA 5
8
7
V
CC
RESET
(Bottom View)
TDFN Package: 3mm x 3mm
0.8mm maximum height - (ZD4)
V
CC
8
RESET 7
CAT1026
1
V
LOW
¯¯¯¯¯¯
2
RESET
3 V
SENSE
4 V
SS
1
V
LOW
¯¯¯¯¯¯
2
RESET
3 V
SENSE
4 V
SS
Doc. No. MD-3010 Rev. P
2
© 2009 SCILLC. All rights reserved.
Characteristics subject to change without notice
CAT1026, CAT1027
PIN DESCRIPTION
¯¯¯¯¯¯
RESET/RESET:
RESET OUTPUTs
(RESET CAT1026 Only)
¯¯¯¯¯¯
These are open drain pins and RESET can be used
as a manual reset trigger input. By forcing a reset
condition on the pin the device will initiate and
maintain a reset condition. 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.
SCL:
SERIAL CLOCK
Serial clock input.
V
SENSE
:
AUXILIARY VOLTAGE MONITOR INPUT
The V
SENSE
input is a second voltage monitor which is
compared against CAT1026 and CAT1027 internal
reference voltage of 1.25 V typically. Whenever the
input voltage is lower than 1.25 V, the open drain V
LOW
output will be driven low. An external resistor divider is
used to set the voltage level to be sensed. Connect
V
SENSE
to V
CC
if unused.
V
LOW
:
AUXILIARY VOLTAGE MONITOR OUTPUT
This open drain output goes low when V
SENSE
is less
than 1.25 V and goes high when V
SENSE
exceeds the
reference voltage.
WDI (CAT1027 Only):
WATCHDOG TIMER INTERRUPT
Watchdog Timer Interrupt Input is used to reset the
watchdog timer. If a transition from high to low or low
to high does not occur every 1.6 seconds, the RESET
outputs will be driven active.
PIN FUNCTION
Pin
Name
¯¯¯¯¯¯
RESET
V
SS
SDA
SCL
RESET
V
CC
V
SENSE
V
LOW
WDI
Function
Active Low Reset Input/Output
Ground
Serial Data/Address
Clock Input
Active High Reset Output
(CAT1026 only)
Power Supply
Auxiliary Voltage Monitor Input
Auxiliary Voltage Monitor Output
Watchdog Timer Interrupt
(CAT1027 only)
OPERATING TEMPERATURE RANGE
Industrial
Extended
-40ºC to 85ºC
-40ºC to 125ºC
CAT10XX FAMILY OVERVIEW
Device
Manual
Reset
Input Pin
Watchdog
Watchdog
Monitor
Pin
SDA
SDA
WDI
Write
Protection
Pin
Independent
Auxiliary
Voltage Sense
RESET:
Active High
and LOW
EEPROM
2k
CAT1021
CAT1022
2k
2k
CAT1023
CAT1024
2k
2k
CAT1025
2k
CAT1026
WDI
CAT1027
2k
For supervisory circuits with embedded 16k EEPROM, please refer to the CAT1161, CAT1162 and CAT1163
data sheets.
© 2009 SCILLC. All rights reserved.
Characteristics subject to change without notice
3
Doc. No. MD-3010 Rev. P
CAT1026, CAT1027
ABSOLUTE MAXIMUM RATINGS
(1)
Parameters
Temperature Under Bias
Storage Temperature
Voltage on any Pin with Respect to Ground
(2)
V
CC
with Respect to Ground
Package Power Dissipation Capability (T
A
= 25°C)
Lead Soldering Temperature (10 s)
Output Short Circuit Current
(3)
Ratings
–55 to +125
–65 to +150
–2.0 to V
CC
+ 2.0
–2.0 to 7.0
1.0
300
100
Units
ºC
ºC
V
V
W
ºC
mA
D.C. OPERATING CHARACTERISTICS
V
CC
= 2.7 V to 5.5 V and over the recommended temperature conditions unless otherwise specified.
Symbol
I
LI
I
LO
I
CC1
I
CC2
I
SB
V
IL(4)
V
IH(4)
V
OL
V
OH
Parameter
Input Leakage Current
Output Leakage Current
Power Supply Current
(Write)
Power Supply Current
(Read)
Standby Current
Input Low Voltage
Input High Voltage
Output Low Voltage
¯¯¯¯¯¯
(SDA, RESET)
Output High Voltage
(RESET)
I
OL
= 3 mA
V
CC
= 2.7 V
I
OH
= -0.4 mA
V
CC
= 2.7 V
CAT102x-45 (V
CC
= 5.0 V)
CAT102x-42 (V
CC
= 5.0 V)
V
TH
Reset Threshold
CAT102x-30 (V
CC
= 3.3 V)
CAT102x-28 (V
CC
= 3.3 V)
CAT102x-25 (V
CC
= 3.0 V)
V
RVALID
V
RT(5)
V
REF
Reset Output Valid V
CC
Voltage
Reset Threshold Hysteresis
Auxiliary Voltage Monitor
Threshold
V
CC
- 0.75
4.50
4.25
3.00
2.85
2.55
1.00
15
1.2
1.25
1.3
4.75
4.50
3.15
3.00
2.70
V
mV
VS
Test Conditions
V
IN
= GND to V
CC
V
IN
= GND to V
CC
f
SCL
= 400 kHz
V
CC
= 5.5 V
f
SCL
= 400 kHz
V
CC
= 5.5 V
CAT1026
Vcc = 5.5 V,
V
IN
= GND or V
CC
CAT1027
-0.5
0.7 x V
CC
Min
-2
-10
Typ
Max
10
10
3
1
50
60
0.3 x V
CC
V
CC
+ 0.5
0.4
Units
µA
µA
mA
mA
µA
V
V
V
V
V
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 minimum DC input voltage is -0.5 V. During transitions, inputs may undershoot to -2.0 V for periods of less than 20 ns. Maximum DC
voltage on output pins is V
CC
+0.5 V, which may overshoot to V
CC
+2.0 V for periods of less than 20 ns.
(3) Output shorted for no more than one second. No more than one output shorted at a time.
(4) V
IL
min and V
IH
max are reference values only and are not tested.
(5) This parameter is tested initially and after a design or process change that affects the parameter. Not 100% tested.
Doc. No. MD-3010 Rev. P
4
© 2009 SCILLC. All rights reserved.
Characteristics subject to change without notice
CAT1026, CAT1027
CAPACITANCE
T
A
= 25ºC, f = 1.0 MHz, V
CC
= 5 V
Symbol
C
OUT (1)
C
IN(1)
Test
Output Capacitance
Input Capacitance
Test Conditions
V
OUT
= 0 V
V
IN
= 0 V
Max
8
6
Units
pF
pF
AC CHARACTERISTICS
V
CC
= 2.7 V to 5.5 V and over the recommended temperature conditions, unless otherwise specified.
Memory Read & Write Cycle
(2)
Symbol
f
SCL
t
SP
t
LOW
t
HIGH
t
R(1)
t
F
(1)
Parameter
Clock Frequency
Input Filter Spike Suppression (SDA, SCL)
Clock Low Period
Clock High Period
SDA and SCL Rise Time
SDA and SCL Fall Time
Start Condition Hold Time
Start Condition Setup Time (for a Repeated Start)
Data Input Hold Time
Data Input Setup Time
Stop Condition Setup Time
SCL Low to Data Out Valid
Data Out Hold Time
Time the Bus must be Free Before a New Transmission Can Start
Write Cycle Time (Byte or Page)
Min
Max
400
100
Units
kHz
ns
µs
µs
1.3
0.6
300
300
0.6
0.6
0
100
0.6
900
50
1.3
5
ns
ns
µs
µs
ns
ns
µs
ns
ns
µs
ms
t
HD; STA
t
SU; STA
t
HD; DAT
t
SU; DAT
t
SU; STO
t
AA
t
DH
t
BUF
(1)
t
WC(3)
Notes:
(1) This parameter is characterized initially and after a design or process change that affects the parameter. Not 100% tested.
(2) Test Conditions according to “AC Test Conditions” table.
(3) 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.
© 2009 SCILLC. All rights reserved.
Characteristics subject to change without notice
5
Doc. No. MD-3010 Rev. P
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