19-1615; Rev 3; 11/05
SOT23, Low-Power µP Supervisory Circuits
with Battery Backup
General Description
The MAX6361–MAX6364 supervisory circuits reduce the
complexity and number of components required for
power-supply monitoring and battery control functions in
microprocessor (µP) systems. The circuits significantly
improve system reliability and accuracy compared to that
obtainable with separate ICs or discrete components.
Their functions include µP reset, backup battery
switchover, and power failure warning.
The MAX6361–MAX6364 operate from supply voltages as
low as +1.2V. The factory-preset reset threshold voltage
ranges from 2.32V to 4.63V (see
Ordering Information).
These devices provide a manual reset input (MAX6361),
watchdog timer input (MAX6362), battery-on output
(MAX6363), and an auxiliary adjustable reset input
(MAX6364). In addition, each part type is offered in three
reset output versions: an active-low open-drain reset, an
active-low open-drain reset, and an active-high open-
drain reset (see
Selector Guide
at end of data sheet).
Features
♦
Low +1.2V Operating Supply Voltage
(V
CC
or V
BATT
)
♦
Precision Monitoring of +5.0V, +3.3V, +3.0V, and
+2.5V Power-Supply Voltages
♦
Debounced Manual Reset Input (MAX6361)
♦
Watchdog Timer with 1.6s Timeout Period
(MAX6362)
♦
Battery-On Output Indicator (MAX6363)
♦
Auxiliary User-Adjustable RESET IN (MAX6364)
♦
Three Available Output Structures
Push-Pull
RESET,
Open-Drain
RESET,
Open-Drain RESET
♦
RESET/RESET Valid Down to 1.2V Guaranteed
(V
CC
or V
BATT
)
♦
Power-Supply Transient Immunity
♦
150ms (min) Reset Timeout Period
♦
Small 6-Pin SOT23 Package
MAX6361–MAX6364
Ordering Information
Applications
Computers
Controllers
Intelligent Instruments
Critical µP/µC
Power Monitoring
Fax Machines
Industrial Control
POS Equipment
Portable/Battery-Powered
Equipment
PART
MAX6361LUT_
_-T
MAX6361PUT_ _-T
MAX6361HUT_ _-T
MAX6362LUT_
_-T
MAX6362PUT_ _-T
MAX6362HUT_ _-T
MAX6363LUT_
_-T
MAX6363PUT_ _-T
MAX6363HUT_ _-T
MAX6364LUT_
_-T
MAX6364PUT_ _-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
PIN-PACKAGE
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
Pin Configurations
TOP VIEW
RESET, RESET
1
6
BATT
GND
2
MAX6361
5
OUT
MAX6364HUT_ _-T
-40°C to +85°C
6 SOT23-6
Note:
These parts offer a choice of reset threshold voltages.
From the table below, select the suffix corresponding to the
desired threshold voltage and insert it into the part number to
complete it. When ordering from the factory, there is a 2500-
piece minimum on the SOT package (tape-and-reel only).
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing "-T" with "+T" when ordering.
SUFFIX
46
44
31
29
26
23
RESET THRESHOLD RANGES (V)
MIN
4.50
4.25
3.00
2.85
2.55
2.25
TYP
4.63
4.38
3.08
2.93
2.63
2.32
MAX
4.75
4.50
3.15
3.00
2.70
2.38
1
MR
3
4
V
CC
SOT23-6
Pin Configurations continued at end of data sheet.
Selector Guide appears at end of data sheet.
Typical Operating Circuit appears at end of data sheet.
________________________________________________________________
Maxim Integrated Products
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
SOT23, Low-Power µP Supervisory Circuits
with Battery Backup
MAX6361–MAX6364
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.......................................................-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 Protection for up to 10s
RESET,
RESET,
BATT ON ..............................................20mA
Continuous Power Dissipation (T
A
= +70°C)
6-Pin SOT23 (derate 8.70mW/°C above +70°C) .........696mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +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
= 3V, T
A
= -40°C to +85°C, reset not asserted. Typical values are at T
A
= +25°C, unless otherwise
noted.) (Note 1)
PARAMETER
Operating Voltage Range,
V
CC
or V
BATT
Supply Current
(Excluding I
OUT
)
I
SUPPLY
in Battery-Backup
Mode (Excluding I
OUT
)
BATT Standby Current
SYMBOL
V
CC
,
V
BATT
I
CC
CONDITIONS
No load (Note 2)
No load, V
CC
> V
TH
,
WDI = V
CC
or GND
(MAX6362)
V
BATT
= 2.8V,
V
CC
= 0
5.5V > V
CC
>
(V
BATT
+ 0.2V)
V
CC
= 2.8V
V
CC
= 3.6V
V
CC
= 5.5V
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
MIN
0
10
11
15
TYP
MAX
5.5
30
35
50
1
3
0.02
0.02
2.75
3.0
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
150
4.63
4.38
3.08
2.93
2.63
2.32
35
280
4.75
4.50
3.15
3.00
2.70
2.38
µs
ms
V
mV
V
Ω
µA
µA
µA
UNITS
V
I
SUPPLY
I
BATT
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
V
OUT
in Battery-Backup Mode
Battery-Switchover Threshold
(V
CC
- V
BATT
)
V
BATT
= 3.0V, I
OUT
≤
10mA
V
BATT
= 2.25V, I
OUT
≤
5mA
V
CC
< V
TH
MAX636_UT46
MAX636_UT44
Reset Threshold
V
TH
MAX636_UT31
MAX636_UT29
MAX636_UT26
MAX636_UT23
V
CC
Falling Reset Delay
Reset-Active Timeout Period
t
RP
V
CC
falling at 10V/ms
Power-up
Power-down
2
_______________________________________________________________________________________
SOT23, Low-Power µP Supervisory Circuits
with Battery Backup
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +2.4V to +5.5V, V
BATT
= 3V, T
A
= -40°C to +85°C, reset not asserted. Typical values are at T
A
= +25°C, unless otherwise
noted.) (Note 1)
PARAMETER
SYMBOL
Reset asserted,
V
BATT
= 0
Reset not asserted
(MAX636_L only)
Reset not asserted
CONDITIONS
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)
0.8
✕
V
CC
0.3
1
V
µA
MIN
TYP
MAX
0.3
0.4
V
UNITS
MAX6361–MAX6364
V
OL
RESET
Output Voltage
V
OH
RESET Output Voltage
RESET,
RESET Output Leakage
Current
MANUAL RESET
(MAX6361 only)
MR
Input Voltage
Pull-Up Resistance
Minimum Pulse Width
Glitch Immunity
MR
to Reset Delay
WATCHDOG INPUT
(MAX6362 only)
Watchdog Timeout Period
Minimum WDI Input Pulse Width
Input Voltage
BATT ON
(MAX6363 only)
Output Voltage
Output Short-Circuit Current
RESET IN
(MAX6364 only)
Input Threshold
RESET IN Leakage Current
RESET IN to Reset Delay
V
OL
t
WD
t
WDI
V
IL
V
IH
V
IL
V
IH
V
OL
I
LK
MAX636_P, MAX636_H only
0.3
✕
V
CC
0.7
✕
V
CC
20
1
V
CC
= 3.3V
V
CC
= 3.3V
1.00
100
0.3
✕
V
CC
0.7
✕
V
CC
I
SINK
= 3.2mA, V
BATT
= 2.1V
Sink current, V
CC
= 5V
Source current, V
BATT
≥
2V
10
1.185
Overdrive voltage = 50mV, RESET IN falling
60
30
1.235
±0.01
1.5
100
1.285
±25
0.4
100
120
1.60
2.25
V
kΩ
µs
ns
ns
s
ns
V
V
mA
µA
V
nA
µs
Note 1:
All devices are 100% production tested at T
A
= +25°C. Limits over temperature are guaranteed by design.
Note 2:
V
BATT
can be 0 anytime or V
CC
can go down to 0 if V
BATT
is active (except at startup).
_______________________________________________________________________________________
3
SOT23, Low-Power µP Supervisory Circuits
with Battery Backup
MAX6361–MAX6364
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
(NO LOAD)
MAX6361 toc01
BATTERY SUPPLY CURRENT
(BACKUP MODE) vs. TEMPERATURE
V
CC
= 0
V
BATT
= 2.8V
MAX6361 toc02
BATTERY TO OUT ON-RESISTANCE
vs. TEMPERATURE
MAX6361 toc03
20
1.2
BATTERY SUPPLY CURRENT (µA)
1.0
0.8
0.6
V
BATT
= 2.0V
0.4
0.2
0
7
BATT TO OUT ON-RESISTANCE (Ω)
6
5
V
BATT
= 2.0V
4
3
2
V
BATT
= 5.0V
1
0
I
OUT
= 25mA
V
CC
= 0
-40
-20
0
20
40
60
80
V
BATT
= 2.8V
SUPPLY CURRENT (µA)
18
16
14
V
BATT
= 0
V
CC
= 5.0V
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
12
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
TEMPERATURE (°C)
V
CC
TO OUT ON-RESISTANCE
vs. TEMPERATURE
MAX6361 toc04
RESET TIMEOUT PERIOD
vs. TEMPERATURE
MAX6361 toc05
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
MAX6361 toc06
1.2
V
OUT
TO OUT ON-RESISTANCE (Ω)
V
CC
= 2.3V
I
OUT
= 25mA
0.9
210
RESET TIMEOUT PERIOD (ms)
205
0.6
V
CC
= 4.5V
I
OUT
= 150mA
0.3
V
CC
= 3.0V
I
OUT
= 65mA
200
195
0
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
190
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
0
TEMPERATURE (°C)
MAX6362
WATCHDOG TIMEOUT PERIOD
vs. TEMPERATURE
MAX6361toc06a
RESET THRESHOLD
vs. TEMPERATURE
MAX6361 toc07
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
MAXIMUM TRANSIENT DURATION (µs)
350
300
250
MAX636_46
200
150
100
50
0
1
MAX636_26
10
100
1k
10k
RESET OCCURS
ABOVE CURVE
MAX6361 toc08
2.0
WATCHDOG TIMEOUT PERIOD (s)
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
5.0
MAX636_46
4.5
THRESHOLD (V)
4.0
3.5
3.0
MAX636_26
2.5
2.0
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
400
RESET THRESHOLD OVERDRIVE V
TH
- V
CC
(mV)
4
_______________________________________________________________________________________
SOT23, Low-Power µP Supervisory Circuits
with Battery Backup
Typical Operating Characteristics (continued)
(T
A
= +25°C, unless otherwise noted.)
BATTERY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6361 toc09
MAX6361–MAX6364
MAX6364
RESET IN THRESHOLD
vs. TEMPERATURE
MAX6361 toc10
MAX6364
RESET IN TO RESET PROPAGATION DELAY
vs. TEMPERATURE
2.8
PROPAGATION DELAY (µs)
2.5
2.2
1.9
1.6
1.3
V
OD
= 50mV
MAX6361 toc11
10
9
BATTERY SUPPLY CURRENT (µA)
8
7
6
5
4
3
2
1
0
0
V
BATT
= 2.3V
1
2
V
CC
(V)
3
4
V
BATT
= 2.5V
V
BATT
= 2.8V
V
TH
= 2.93V
1.236
THRESHOLD (V)
1.235
1.234
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
1.0
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
Pin Description
PIN
NAME
FUNCTION
Active-High Reset Output. RESET is continuously high when V
CC
is below the reset threshold (V
TH
),
MR
is
low, or RESET IN is low. It asserts in pulses when the internal watchdog times out. RESET remains high
for the reset timeout period (t
RP
) after V
CC
rises above the reset threshold, after the manual reset input
goes from low to high, after RESET IN goes high, or after the watchdog triggers a reset event. The
MAX636_H is an active-high open-drain output.
Active-Low Reset Output.
RESET
is continuously low when V
CC
is below the reset threshold (V
TH
),
MR
is
low, or RESET IN is low. It asserts in pulses when the internal watchdog times out.
RESET
remains low for
the reset timeout period (t
RP
) after V
CC
rises above the reset threshold, after the manual reset input goes
from low to high, after RESET IN goes high, or after the watchdog triggers a reset event. The MAX636_L
is an active-low push-pull output while the MAX636_P is an active-low open-drain output.
Ground
MAX6361
Manual-Reset Input. Maintaining logic low on
MR
asserts a reset. Reset output remains assert-
ed for at least 150ms (t
RP
) after
MR
transitions from low to high. Leave unconnected or connected to V
CC
if not used.
MAX6362
Watchdog Input. If WDI remains high or low for longer than the watchdog timeout period (t
WD
), the
internal watchdog timer runs out and a reset pulse is triggered for the reset timeout period (t
RP
) (Figure 1). The
internal watchdog clears whenever reset asserts or whenever WDI sees a rising or falling edge.
MAX6363
Battery-On Output. BATT ON goes high in battery backup mode.
MAX6364
Reset Input. When RESET IN falls below 1.235V, reset is asserted. Reset output remains
asserted as long as RESET IN is low and for at least 150ms (t
RP
) after RESET IN goes high.
Supply Voltage, 0 to 5.5V. Reset is asserted when V
CC
drops below the reset threshold voltage (V
TH
).
Reset remains asserted until V
CC
rises above V
TH
and for at least 150ms after V
CC
rises above V
TH
.
Output. OUT sources from V
CC
when it is above the reset threshold (V
TH
), and from the greater of V
CC
or
BATT when V
CC
is below V
TH
.
Backup-Battery Input. When V
CC
falls below the reset threshold, BATT switches to OUT if V
BATT
is 20mV
greater than V
CC
. When V
CC
rises 20mV above V
BATT
, V
CC
switches to OUT. The 40mV hysteresis
prevents repeated switching if V
CC
falls slowly.
_______________________________________________________________________________________
5
RESET
1
RESET
2
GND
MR
3
WDI
BATT ON
RESET IN
4
5
V
CC
OUT
6
BATT
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