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General Description
The MAX6351–MAX6360 microprocessor (µP) supervi-
sors with multiple reset voltages significantly improve
system reliability and accuracy compared to separate
ICs or discrete components. If any input supply voltage
drops below its associated preset threshold, all reset
outputs are asserted. In addition, the output(s) is valid
as long as either input supply voltage remains greater
than +1.0V.
All devices in this series have an active-low debounced
manual reset input. In addition, the MAX6358/MAX6359/
MAX6360 offer a watchdog timer input with a 46.4sec
start-up timeout period and a 2.9sec timeout period.
The MAX6355/MAX6356/MAX6357 offer an additional
voltage monitor input to monitor a third voltage.
The MAX6351 features both 3V and 5V active-low push-
pull reset outputs. The MAX6353/MAX6356/MAX6359
offer a 5V active-low push-pull reset. The MAX6354/
MAX6357/MAX6360 offer a 3V active-low push-pull
reset. The MAX6352/MAX6355/MAX6358’s reset is
active-low open-drain.
All of these devices are offered with a wide variety of
voltage threshold levels, as shown in the
Voltage
Threshold Levels table below. They are available in 5-
and 6-pin SOT23 packages and operate over the
extended (-40°C to +85°C) temperature range.
Applications
Computers
Intelligent Instruments
Controllers
Multivoltage Systems
Portable/Battery-Powered
Equipment
Features
o
Precision Monitoring of Multiple +2.5V, +3.0V,
+3.3V, and +5V Power-Supply Voltages
o
Precision Factory-Set Power-Supply
Reset Thresholds
o
20µA Supply Current
o
100ms min Power-On Reset Pulse Width
o
Fully Guaranteed Over Temperature
o
Guaranteed
RESET
Valid to V
CC
5 = 1V or
V
CC
3 = 1V
o
Power-Supply Transient Immunity
o
No External Components for Dual-Voltage
Systems
o
Small 5- and 6-Pin SOT23 Packages
o
Debounced TTL/CMOS-Compatible
Manual-Reset Input
o
Watchdog Timer
46.4sec Start-Up Timeout
2.9sec Normal Timeout
o
Low Cost
MAX6351–MAX6360
Dual/Triple-Voltage
µP Supervisory Circuits
________________________________________________________________
Maxim Integrated Products
1
19-1508; Rev 1; 10/99
*
The _ _ are placeholders for the threshold voltage levels of the
devices. Substitute the part number suffix in the Voltage
Threshold Levels table for the desired voltage level. There are
two standard versions for each of the above part numbers. All
devices are available in tape-and-reel only.
Ordering Information
PART*
MAX6351
_ _UT-T
MAX6352
_ _UK-T
MAX6353
_ _UK-T
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
TEMP. RANGE
PIN-PACKAGE
6 SOT23-6
5 SOT23-5
5 SOT23-5
MAX6354
_ _UK-T
MAX6355
_ _UT-T
MAX6356
_ _UT-T
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
5 SOT23-5
6 SOT23-6
6 SOT23-6
MAX6357
_ _UT-T
MAX6358
_ _UT-T
MAX6359
_ _UT-T
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
6 SOT23-6
6 SOT23-6
6 SOT23-6
MAX6360
_ _UT-T
-40°C to +85°C
6 SOT23-6
PART NO.
SUFFIX
(_ _)
V
CC
5 NOMINAL
VOLTAGE
THRESHOLD (V)
V
CC
3 NOMINAL
VOLTAGE
THRESHOLD (V)
LT
4.63
3.08
LS
LR
4.63
2.63
4.63
2.93
MT
MS
4.38
2.93
MR
4.38
3.08
TY
3.08
2.19
4.38
2.63
SY
2.93
2.19
Note:
Standard versions are shown in bold and have a required
order increment of 2500 pieces. Sample stock is generally held on
the standard versions only. The required order increment for non-
standard versions is 10,000 pieces. Contact factory for availability.
__________Voltage Threshold Levels
Pin Configurations appear at end of data sheet.
Selector Guide appears at end of data sheet.
MAX6351–MAX6360
Dual/Triple-Voltage
µP Supervisory Circuits
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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.
V
CC
5, V
CC
3 to GND .................................................-0.3V to +6V
RST (MAX6352/55/58) ............................................. -0.3V to +6V
RST, MR, WDI, RST5, RSTIN
(MAX6351/53/56/59).............................-0.3V to (V
CC
5 + 0.3V)
RST, RST3 (MAX6351/54/57/60) .................-3V to (V
CC
3 + 0.3V)
Input/Output Current, All Pins .............................................20mA
Continuous Power Dissipation (T
A
= +70°C)
5-Pin SOT23-5 (derate 7.1mW/°C above +70°C) ........571mW
6-Pin SOT23-6 (derate 7.1mW/°C above +70°C) ........571mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10sec) .............................+300°C
100mV overdrive
V
CC
5 = 5.5V, V
CC
3 = 3.6V, all I/O pins open
V
CC
to Reset Delay
T
A
= -40°C to +85°C
MAX63_ _ _Y
T
A
= 0°C to +70°C
MAX63_ _ _R
MAX63_ _S_
MAX63_ _ _S
MAX63_ _T_
MAX63_ _ _T
MAX63_ _M_
CONDITIONS
µs
20
V
V
TH
/500
Reset Threshold Hysteresis
ppm/°C
20
∆
V
TH
/°C
Reset Threshold Tempco
2.13
2.25
2.16
2.19
2.22
2.55
2.70
2.58
2.63
2.68
2.85
3.00
2.88
2.93
2.98
3.00
3.15
V
3.03
3.08
3.14
V
TH
3
V
CC
3 Threshold (Note 3)
2.85
3.00
µA
20
50
I
CC
5 +
I
CC
3
Supply Current
1.2
5.5
V
1.0
5.5
V
CC
Supply Voltage Range (Note 2)
2.88
2.93
2.98
3.00
3.15
3.03
3.08
3.14
4.25
4.50
V
4.54
4.63
4.72
V
TH
5
V
CC
5 Threshold (Note 3)
4.5
4.75
4.3
4.38
4.46
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
V
CC
5 > V
TH
5
(MAX)
, V
CC
3 > V
TH
3
(MAX)
V
CC
5 or V
CC
3
≥
2.7V, I
SINK
= 1.2mA
V
CC
5 or V
CC
3
≥
4.5V, I
SINK
= 3.2mA
V
CC
5 or V
CC
3 < 1V, I
SINK
= 50µA,
T
A
= 0°C to +70°C
ms
100
180
280
t
RP
Reset Timeout Period
0.3
0.4
V
0.3
T
A
= +25°C
MAX63_ _L_
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
ELECTRICAL CHARACTERISTICS
(V
CC
3 = V
CC
5 = +1.2V to +5.5V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
V
CC
5 or V
CC
3 < 1.2V, I
SINK
= 50µA
V
OL
RESET Output Voltage Low
0.3
V
MAX6351–MAX6360
Dual/Triple-Voltage
µP Supervisory Circuits
_______________________________________________________________________________________
3
Note 1:
Overtemperature limits are guaranteed by design and not production tested.
Note 2:
The reset output is guaranteed to be in the correct state if either V
CC
3 or V
CC
5 is within its specified region of operation.
Note 3:
The reset output(s) is asserted if either V
CC
5 or V
CC
3 drops below its associated trip point.
Note 4:
Guaranteed by design. Not production tested.
Note 5:
WDI is internally serviced within the watchdog timeout period if WDI is left unconnected.
Note 6:
The WDI input current is specified as the average input current when the WDI input is driven high or low.
MAX6351/MAX6353/
MAX6354/MAX6356/
MAX6357/MAX6359/
MAX6360
(_Y versions only),
V
CC
5 > V
TH
5
(MAX)
,
V
CC
3 > V
TH
3
(MAX)
CONDITIONS
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
MAX63_ _ _Y, V
CC
5 > V
TH
5
(MAX)
MAX63_ _ _Y, V
CC
5 > V
TH
5
(MAX)
MAX63_ _L_, MAX63_ _M_, V
CC
5 > V
TH
5
(MAX)
MAX63_ _L_, MAX63_ _M_, V
CC
5 > V
TH
5
(MAX)
V
WDI
= 0
V
WDI
= V
CC
First timeout period after reset
MAX6351/MAX6353/
MAX6354/MAX6356/
MAX6357/MAX6359/
MAX6360
(L_, M_ versions only),
V
CC
5 > V
TH
5
(MAX)
,
V
CC
3 > V
TH
3
(MAX)
V
CC
3 = 5V
V
IL
= 0.4V, V
IH
= 0.8V
CC
µs
10
t
RP
MR Minimum Pulse Width
k
Ω
32 63.5
100
MR Pull-Up Resistance
0.7V
CC
2.3
V
IL
0.8
MR Input
V
-20
-15
µA
120
160
WDI Input Current (Note 6)
0.7V
CC
V
IH
V
0.3V
CC
V
IL
WDI Input Threshold (Note 5)
ns
50
t
WDI
WDI Pulse Width (Note 4)
1.6
2.9
4.5
sec
25.6
46.4
72.0
t
WD
Watchdog Timeout Period
V
CC
- 1.5
0.8V
CC
0 < V
RISTIN
< V
CC
5 - 0.3V
V
CC
5 > V
TH
5
(MAX),
V
CC
3 > V
TH
3
(MAX)
mV
2.5
RSTIN Hysteresis
nA
-25
25
I
RSTIN
RSTIN Input Current
1.19
1.25
V
1.20
1.22
1.24
V
RSTIN
RSTIN Input Threshold
µs
0.1
t
MD
MR to Reset Delay
ns
100
MR Glitch Rejection
T
A
= +25°C
T
A
= -40°C to +85°C
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
3 = V
CC
5 = +1.2V to +5.5V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
WATCHDOG INPUT
(MAX6358/MAX6359/MAX6360)
MANUAL RESET INPUT
ADJUSTABLE RESET COMPARATOR INPUT
(MAX6355/MAX6356/MAX6357)
I
SOURCE
= 500µA
V
OH
RESET Output Voltage High
I
SOURCE
= 800µA
V
After first WDI falling edge
0.3V
CC
V
IL
V
IH
V
IH
MAX6351–MAX6360
Dual/Triple-Voltage
µP Supervisory Circuits
4
_______________________________________________________________________________________
Typical Operating Characteristics
(V
CC
= +5V, T
A
= +25°C, unless otherwise noted.)
0
5
10
15
20
-40
10
-15
35
60
85
SUPPLY CURRENT vs. TEMPERATURE
MAX6351/60-01
TEMPERATURE (°C)
SUPPLY CURRENT (
µ
A)
I
CC
5 (V
CC
5 = 5.0V, V
CC
3 = 3.3V)
I
CC
3 (V
CC
5 = 5.0V, V
CC
3 = 3.3V)
I
CC
3 (V
CC
5 = 3.3V, V
CC
3 = 2.5V)
I
CC
5 (V
CC
5 = 3.3V, V
CC
3 = 2.5V)
V
CC
5 (V)
RESET vs. V
CC
5 (V
CC
3 = 3V)
V
TH
0
1.0
0.5
2.0
1.5
3.0
2.5
3.5
4.5
4.0
5.0
0
1.0 1.5 2.0
0.5
2.5 3.0 3.5
4.5
4.0
5.0
MAX6351/60-02
RESET (V)
0
1.0
0.5
2.0
1.5
3.0
2.5
3.5
4.5
4.0
5.0
0
1.0 1.5 2.0
0.5
2.5 3.0 3.5
4.5
4.0
5.0
MAX6351/60-03
V
CC
5 (V)
RESET (V)
RESET vs. V
CC
5 (V
CC
3 = GND)
MAX6351
MAX6360
10k
V
CC
5 OR V
CC
3
V
CC
RST5
RST3
RST
0.80
0.90
0.85
1.00
0.95
1.05
1.10
1.15
1.20
-60
-20
0
-40
20
40
60
80
100
NORMALIZED RESET/WATCHDOG
PERIOD vs. TEMPERATURE
MAX6351/60-04
TEMPERATURE (°C)
NORMALIZED PERIOD
OPEN-DRAIN
OUTPUT
0
0
0
5V
3V
5V PUSH-PULL
OUTPUT
3V PUSH-PULL
OUTPUT
5V
PULL-UP CHARACTERISTICS
MAX6351/60-07
400ns/div
300
0
0.01
0.1
1
MAXIMUM V
CC
TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
100
50
MAX6351/60-05
RESET THRESHOLD OVERDRIVE, V
RST
- V
CC
(V)
TRANSIENT DURATION (
µ
s)
150
200
250
RESET OCCURS ABOVE LINE
0
50
100
150
200
250
0
0.4 0.5
0.2 0.3
0.1
0.6 0.7 0.8 0.9 1.0
RESET DELAY vs.
RESET THRESHOLD OVERDRIVE
MAX6351/60-06
RESET THRESHOLD OVERDRIVE, V
RST
- V
CC
(V)
RESET DELAY (
µ
s)
DELAY FROM FALL OF V
CC
5
DELAY FROM FALL OF V
CC
3
0
5V
PULL-DOWN CHARACTERISTICS
AND MANUAL RESET DELAY
40ns/div
0
5V
MR
MAX6351/60-08
0
0
5V
5V
OPEN-DRAIN
OUTPUT
5V PUSH-PULL
OUTPUT
3V PUSH-PULL
OUTPUT
MAX6351–MAX6360
Dual/Triple-Voltage
µP Supervisory Circuits
_______________________________________________________________________________________
5
—
1
1
2
2
2
—
—
5
5
—
—
4
4
4
3
3
3
6
5
6
—
—
—
Pin Description
FUNCTION
Active-Low Reset Output. Open-drain for the
MAX6352/MAX6355/MAX6358, 5V push-pull for the
MAX6353/MAX6356/MAX6359, and 3V push-pull for
the MAX6354/MAX6357/MAX6360.
Ground
Undervoltage Reset Comparator Input. Asserts
reset when the monitored voltage falls below 1.23V.
Set the reset threshold with an external resistor-
divider. Connect to V
CC
5 if unused. V
RSTIN
must be
below V
CC
5.
Active-Low, 3V CMOS Reset Output
+3.3V/+3.0V Supply Input. Powers the device when
it is above V
CC
5 and monitors its own voltage.
Manual-Reset Input. Pull low to force a reset. RST,
RST5, and RST3 remain active as long as MR is low
and for the timeout period after MR goes high.
Leave unconnected or connect to V
CC
5 if unused.
V
MR
must be below V
CC
5.
+5V Supply Input. Powers the device when it is
above V
CC
3 and monitors its own voltage.
Watchdog Input. If WDI remains either high or low
longer than the timeout period, then reset is trig-
gered. The timer clears when reset is asserted or
whenever WDI sees a rising or falling edge. Leave
floating to disable it if unused.
1
2
—
—
4
3
6
5
NAME
RST
GND
RSTIN
RST3
V
CC
3
MR
V
CC
5
WDI
1
—
—
Active-Low, 5V CMOS Reset Output
—
RST5
MAX6351
MAX6352
MAX6353
MAX6354
MAX6355
MAX6356
MAX6357
MAX6358
MAX6359
MAX6360
PIN
6
_______________________________________________________________________________________
MAX6351–MAX6360
Detailed Description
Supply Voltages
The MAX6351–MAX6360 microprocessor (µP) superviso-
ry circuits maintain system integrity by alerting the µP to
fault conditions. These ICs monitor multiple-supply sys-
tems and derive their internal power from the highest volt-
age source present at V
CC
5 and V
CC
3. In addition, the
output reset state is guaranteed to remain viable while
either V
CC
5 or V
CC
3 is above +1V.
Threshold Levels
All the possible input voltage threshold level combina-
tions are indicated by a two-letter code in
Voltage
Threshold Levels. The two standard combinations are
LS and SY. LS parts monitor one +5V ±5% supply and
one +3.3V ±10% supply. SY parts monitor one +3.3V
±10% supply and one +2.5V ±10% supply. The other
combinations also monitor +5V ±10% supplies, +3.3V
±5% supplies, and +3V ±5% supplies.
Reset Outputs
The MAX6351 provides a 5V active-low reset and a 3V
active-low reset. The MAX6353/MAX6356/MAX6359 pro-
vide a 5V active-low push-pull reset and the MAX6354/
MAX6357/MAX6360 provide a 3V active-low push-pull
reset. The MAX6353/MAX6355/MAX6358 provide an
active-low open-drain reset. The higher input voltages of
V
CC
5 and V
CC
3 maintain the sinking capability of the
low reset-output state. The reset outputs are maintained
as long as either supply is above +1V.
Negative-Going V
CC
Transients
The MAX6351–MAX6360 are designed to ignore short
negative-going V
CC
5 and V
CC
3 transients. See
Typical
Operating Characteristics for a glitch immunity graph.
Third Input Voltage
(MAX6355/MAX6356/MAX6357)
The MAX6355/MAX6356/MAX6357 provide an addition-
al input to monitor a third voltage. The threshold voltage
at RSTIN is typically 1.22V. To monitor a voltage higher
than 1.22V, connect a resistor-divider to the circuit as
shown in Figure 2. The threshold at V
3
is:
Note that RSTIN is powered by V
CC
5, and its voltage
must therefore remain lower than V
CC
5.
V
1.22
R1
R2
R2
3TH
=
+
Dual/Triple-Voltage
µP Supervisory Circuits
WATCHDOG
TIMER
V
CC
5
(5) 6
4
(5)
(5)
2
GND
NOTE: PIN 1 IS RST5 FOR THE MAX6351 AND RST FOR THE
MAX6352–MAX6360. PIN 5 IS RST3 FOR THE MAX6351, RSTIN
FOR THE MAX6355/56/57, WDI FOR THE MAX6358/59/60,
AND V
CC
FOR THE MAX6352/53/54.
V
CC
3
MR
(RSTIN)
RST (1)
RST3 (5)
(1)
RST5
(WDI)
RESET
GENERATOR
GLITCH
FILTER
MAX6351–MAX6360
V
TH
5
V
TH
3
1.22V
3
Figure 1. Functional Diagram
Figure 2. Monitoring a Third Voltage
V3
R1
R2
V
CC
5
≥
V
RSTIN
RSTIN
MAX6355
MAX6356
MAX6357
Watchdog Input
(MAX6358/MAX6359/MAX6360)
The MAX6358/MAX6359/MAX6360 include a WDI to
provide a reset if the µP goes into an infinite loop. After
a reset, the start-up timeout period and the initial time-
out period is nominally 46.4sec to allow the µP time to
initialize. After the first transition on the WDI and after
any toggle of the watchdog thereafter, the timeout peri-
od is nominally 2.9sec.
Applications Information
Ensuring a Valid
RESET Output
Down to V
CC
= 0
In some systems, it is necessary to ensure a valid reset
even if V
CC
falls to 0. In these applications, use the cir-
cuit shown in Figure 3. Note that this configuration does
not work for the open-drain outputs of the MAX6352/
MAX6355/MAX6358.
Monitoring a Negative Voltage
To monitor a negative supply rail using RSTIN or the
MAX6355/MAX6356/MAX6357, use the circuit shown in
Figure 4. In this configuration, a reset is issued when
the negative supply falls below V
INTH
.
Interfacing to µPs with