19-1658; Rev 2; 5/05
SOT23, Low-Power µP Supervisory Circuits
with Battery Backup and Chip-Enable Gating
General Description
The MAX6365–MAX6368 supervisory circuits simplify
power-supply monitoring, battery-backup control func-
tions, and memory write protection in microprocessor
(µP) systems. The circuits significantly improve the size,
accuracy, and reliability of modern systems with an ultra-
small integrated solution.
These devices perform four basic system functions:
1) Provide a µP reset output during V
CC
supply power-
up, power-down, and brownout conditions.
2) Internally control V
CC
to backup-battery switching to
maintain data or low-power operation for CMOS
RAM, CMOS µPs, real-time clocks, and other digital
logic when the main supply fails.
3) Provide memory write protection through internal
chip-enable gating during supply or processor faults.
4) Include one of the following options: a manual reset
input (MAX6365), a watchdog timer function
(MAX6366), a battery-on output (MAX6367), or an
auxiliary user-adjustable reset input (MAX6368).
The MAX6365–MAX6368 operate from V
CC
supply volt-
ages as low as 1.2V. The factory preset reset threshold
voltages range from 2.32V to 4.63V (see
Ordering
Information).
In addition, each part is offered in three
reset output versions: push-pull active low, open-drain
active low, or open-drain active high (see
Selector
Guide).
The MAX6365–MAX6368 are available in minia-
ture 8-pin SOT23 packages.
Features
o
Low +1.2V Operating Supply Voltage (V
CC
or V
BATT
)
o
Precision Monitoring of +5.0V, +3.3V, +3.0V, and
+2.5V Power-Supply Voltages
o
On-Board Gating of Chip-Enable Signals, 1.5ns
Propagation Delay
o
Debounced Manual Reset Input (MAX6365)
o
Watchdog Timer, 1.6s Timeout (MAX6366)
o
Battery-On Output Indicator (MAX6367)
o
Auxiliary User-Adjustable RESET IN (MAX6368)
o
Low 10µA Quiescent Supply Current
o
Three Available Output Structures
Push-Pull
RESET
Open-Drain
RESET
Open-Drain RESET
o
RESET/RESET Valid Down to 1.2V Guaranteed
(V
CC
or V
BATT
)
o
Power-Supply Transient Immunity
o
150ms min Reset Timeout Period
o
Miniature 8-Pin SOT23 Package
MAX6365–MAX6368
Ordering Information
PART*
MA X6 36 5
LKA_ _-T
MAX6365PKA_ _-T
MAX6365HKA_ _-T
MA X6 36 6
LKA_ _-T
MAX6366PKA_ _-T
MAX6366HKA_ _-T
MA X6 36 7
LKA_ _-T
MAX6367PKA_ _-T
MAX6367HKA_ _-T
MA X6 36 8
LKA_ _-T
MAX6368PKA_ _-T
MAX6368HKA_ _-T
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
8 SOT23-8
Applications
Critical µP/µC Power
Monitoring
Fax Machines
Industrial Control
Computers/Controllers
Portable/Battery-
Powered Equipment
Set-Top Boxes
POS Equipment
Pin Configurations
TOP VIEW
RESET, RESET
CE IN
GND
1
2
8
7
CE OUT
BATT
OUT
V
CC
MAX6365
3
6
5
MR
4
*These parts offer a choice of reset threshold voltages. From the
Reset Threshold Ranges table, insert the desired threshold volt-
age code in the blank to complete the part number. SOT parts
come in tape-and-reel only and must be ordered in 2500-piece
increments. See Device Marking Codes for a complete parts list,
including SOT top marks and standard threshold versions. See
Selector Guide for a listing of device features.
SOT23
Pin Configurations continued at end of data sheet.
Typical Operating Circuit appears at end of data sheet.
1
________________________________________________________________
Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
SOT23, Low-Power µP Supervisory Circuits
with Battery Backup and Chip-Enable Gating
MAX6365–MAX6368
ABSOLUTE MAXIMUM RATINGS
Terminal Voltages (with respect to GND)
V
CC
, BATT, OUT.......................................................-0.3V to +6V
RESET
(open drain), RESET (open drain) ................-0.3V to +6V
BATT ON,
RESET
(push-pull), RESET IN,
WDI,
CE
IN,
CE
OUT ...........................-0.3V to (V
OUT
+ 0.3V)
MR
..............................................................-0.3V to (V
CC
+ 0.3V)
Input Current
V
CC
Peak ..............................................................................1A
V
CC
Continuous .............................................................250mA
BATT Peak .....................................................................250mA
BATT Continuous .............................................................40mA
GND ...............................................................................75mA
Output Current
OUT ...............................Short-Circuit Protected for up to 10s
RESET,
RESET,
BATT ON,
CE
OUT...............................20mA
Continuous Power Dissipation (T
A
= +70°C)
8-Pin SOT23 (derate 8.75mW/°C above +70°C)........700mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature .....................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond 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 beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
CC
= +2.4V to +5.5V, V
BATT
= +3.0V,
CE
IN = V
CC
, reset not asserted, T
A
= -40°C to +85°C. Typical values are at T
A
= +25°C,
unless otherwise noted.) (Note 1)
PARAMETER
Operating Voltage Range
(Note 2)
Supply Current
(Excluding I
OUT
)
Supply Current in Battery-
Backup Mode (Excluding I
OUT
)
BATT Standby Current
SYMBOL
V
CC
, V
BATT
No load
V
CC
= 2.8V
I
CC
No load, V
CC
> V
TH
V
BATT
= 2.8V,
V
CC
= 0
5.5V > V
CC
> (V
BATT
+ 0.2V)
V
CC
= 3.6V
V
CC
= 5.5V
I
BACK
I
BATT
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
-0.1
-1.0
CONDITIONS
MIN
0
10
12
15
TYP
MAX
5.5
30
35
50
1
3
0.02
0.02
3.1
3.7
4.6
V
BATT
-
0.2
V
BATT
-
0.15
V
BATT
-
0.15
20
-20
4.50
4.25
3.00
2.85
2.55
2.25
4.63
4.38
3.08
2.93
2.63
2.32
20
4.75
4.50
3.15
3.00
2.70
2.38
µs
V
Ω
µA
µA
µA
UNITS
V
V
CC
= 4.75V, I
OUT
= 150mA
V
CC
to OUT On-Resistance
R
ON
V
CC
= 3.15V, I
OUT
= 65mA
V
CC
= 2.38V, I
OUT
= 25mA
V
BATT
= 4.5V, I
OUT
= 20mA
Output Voltage in Battery-
Backup Mode
V
OUT
V
BATT
= 3.0V, I
OUT
= 10mA
V
BATT
= 2.25V, I
OUT
= 5mA
Battery-Switchover Threshold
(V
CC
- V
BATT
)
V
SW
V
CC
< V
TH
MAX636_ _KA46
MAX636_ _KA44
Reset Threshold
V
TH
MAX636_ _KA31
MAX636_ _KA29
MAX636_ _KA26
MAX636_ _KA23
V
CC
Falling Reset Delay
t
RD
V
CC
falling at 10V/ms
Power-up
Power-down
V
mV
2
_______________________________________________________________________________________
SOT23, Low-Power µP Supervisory Circuits
with Battery Backup and Chip-Enable Gating
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +2.4V to +5.5V, V
BATT
= +3.0V,
CE
IN = V
CC
, reset not asserted, T
A
= -40°C to +85°C. Typical values are at T
A
= +25°C,
unless otherwise noted.) (Note 1)
PARAMETER
Reset Active Timeout Period
SYMBOL
t
RP
Reset asserted,
V
BATT
= 0
Reset not asserted
(MAX636_L only)
Reset not asserted
Reset not asserted,
V
BATT
= 0
(MAX636_H only)
(Note 3)
I
SINK
= 1.6mA,
V
CC
> 2.1V
I
SINK
= 100µA,
V
CC
> 1.2V
I
SOURCE
= 500µA,
V
CC
> V
TH(MAX)
I
SINK
= 1.6mA,
V
CC
> V
TH (MAX)
I
SOURCE
= 1mA,
V
CC
> 1.8V
I
SOURCE
= 200µA,
V
CC
> 1.2V
0.7
✕
V
CC
0.8
✕
V
CC
1
0.3
✕
V
CC
0.7
✕
V
CC
20
1
V
CC
= 3.3V
V
CC
= 3.3V
t
WD
t
WDI
V
IL
WDI Input Voltage
V
IH
WDI Input Current
BATT ON
(MAX6367 only)
Output Voltage
Output Short-Circuit Current
V
OL
I
SINK
= 3.2mA, V
BATT
= 2.1V
Sink current, V
CC
= 5V
Source current, V
BATT
> 2V
10
60
30
100
0.4
V
mA
µA
0.7
✕
V
CC
-1.0
1.0
µA
1.00
100
0.3
✕
V
CC
100
120
1.65
2.25
kΩ
µs
ns
ns
s
ns
µA
0.8
✕
V
CC
0.3
V
CONDITIONS
MIN
150
TYP
MAX
280
0.3
0.4
V
UNITS
ms
MAX6365–MAX6368
V
OL
RESET
Output Voltage
V
OH
V
OL
RESET Output Voltage
V
OH
RESET
Output Leakage Current
MANUAL RESET
(MAX6365 only)
I
LKG
MAX636_P and MAX636_H only
V
IL
MR
Input Voltage
V
IH
Pullup Resistance
Minimum Pulse Width
Glitch Immunity
MR
to Reset Delay
WATCHDOG
(MAX6366 only)
Watchdog Timeout Period
Minimum WDI Input Pulse Width
V
V
_______________________________________________________________________________________
3
SOT23, Low-Power µP Supervisory Circuits
with Battery Backup and Chip-Enable Gating
MAX6365–MAX6368
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +2.4V to +5.5V, V
BATT
= +3.0V,
CE
IN = V
CC
, reset not asserted, T
A
= -40°C to +85°C. Typical values are at T
A
= +25°C,
unless otherwise noted.) (Note 1)
PARAMETER
RESET IN
(MAX6368 only)
RESET IN Threshold
RESET IN Leakage Current
RESET IN to Reset Delay
CHIP-ENABLE GATING
CE
IN Leakage Current
CE
IN to
CE
OUT Resistance
CE
OUT Short-Circuit Current
CE
IN to
CE
OUT Propagation
Delay
Reset asserted
Reset not asserted (Note 4)
Reset asserted,
CE
OUT = 0
50Ω source,
C
LOAD
= 50pF
V
CC
= 4.75V
V
CC
= 3.15V
0.8
✕
V
CC
V
V
CC
= 0, V
BATT
> 2.2V, I
SOURCE
= 1µA
Reset-to-CE OUT Delay
V
BATT
-
0.1
12
µs
20
0.75
1.5
2
±1
100
2.0
7
9
µA
Ω
mA
ns
V
OD
= 50mV, RESET IN falling
V
RTH
1.185
1.235
±0.01
1.5
1.285
±25
V
nA
µs
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
CC
= 5V, V
CC
> V
BATT
, I
SOURCE
= 100µA
CE
OUT Output Voltage High
Note 1:
Note 2:
Note 3:
Note 4:
All devices are 100% production tested at T
A
= +25°C. Limits over temperature are guaranteed by design.
V
BATT
can be 0 anytime, or V
CC
can go down to 0 if V
BATT
is active (except at startup).
RESET is pulled up to OUT. Specifications apply for OUT = V
CC
or OUT = BATT.
The chip-enable resistance is tested with V
CC
= V
TH(MAX)
and
CE
IN = V
CC
/2.
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. TEMPERATURE (NO LOAD)
MAX6365/8-01
BATTERY SUPPLY CURRENT
(BACKUP MODE) vs. TEMPERATURE
MAX6365/8-02
BATT-TO-OUT ON-RESISTANCE
vs. TEMPERATURE
7
6
5
4
3
2
1
0
I
OUT
= 25mA
V
CC
= 0
-40
-20
0
20
40
60
80
V
BATT
= 2.8V
V
BATT
= 5.0V
V
BATT
= 2.0V
MAX6365/8-03
16
15
SUPPLY CURRENT (µA)
14
13
12
11
10
9
8
1.2
BATTERY SUPPLY CURRENT (µA)
1.0
0.8
0.6
V
BATT
= 2.0V
0.4
0.2
0
V
BATT
= 2.8V
-40
-20
0
20
40
60
80
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
TEMPERATURE (°C)
BATT-TO-OUT ON-RESISTANCE (Ω)
V
CC
= 5.0V
V
BATT
= 0
V
CC
= 0
8
TEMPERATURE (°C)
4
_______________________________________________________________________________________
SOT23, Low-Power µP Supervisory Circuits
with Battery Backup and Chip-Enable Gating
MAX6365–MAX6368
Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
V
CC
TO OUT ON-RESISTANCE
vs. TEMPERATURE
MAX6365/8-04
RESET TIMEOUT PERIOD
vs. TEMPERATURE
MAX6365/8-05
V
CC
TO RESET PROPAGATION DELAY
vs. TEMPERATURE
135
120
PROPAGATION DELAY (µs)
105
90
75
60
45
30
15
10V/ms
-40
-20
0
20
40
60
80
1V/ms
V
CC
FALLING
0.25V/ms
MAX6365/8-06
1.4
V
CC
TO OUT ON-RESISTANCE (Ω)
1.2
1.0
0.8
0.6
0.4
0.2
0
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
V
CC
= 4.5V
I
OUT
= 150mA
V
CC
= 3.0V
I
OUT
= 65mA
V
CC
= 2.3V
I
OUT
= 25mA
210
RESET TIMEOUT PERIOD (ms)
205
200
195
190
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
0
TEMPERATURE (°C)
RESET THRESHOLD
vs. TEMPERATURE
MAX6365/8-07
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
MAX6365/8-08
BATTERY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
9
BATTERY SUPPLY CURRENT (µA)
8
7
6
5
4
3
2
1
0
V
BATT
= 2.3V
V
BATT
= 2.5V
V
BATT
= 2.8V
V
TH
= 2.93V
MAX6365/8-09
5.0
MAX636_ 46 (V
TH
= 4.63V)
4.5
THRESHOLD (V)
4.0
3.5
3.0
MAX636_ 26 (V
TH
= 2.63V)
2.5
2.0
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
400
MAXIMUM TRANSIENT DURATION (µs)
350
300
250
200
150
100
50
0
1
10
100
1000
MAX636_ 26
(V
TH
= 2.63V)
RESET OCCURS
ABOVE CURVE
MAX636_ 46
(V
TH
= 4.63V)
10
10,000
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
RESET THRESHOLD OVERDRIVE V
TH
- V
CC
(mV)
V
CC
(V)
_______________________________________________________________________________________
5
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