19-2690; Rev 2; 12/07
Power-Supply Monitor with Reset
General Description
The MAX700/MAX701/MAX702 are supervisory circuits
used to monitor the power supplies in microprocessor
(µP) and digital systems. The
RESET/RESET
outputs of
the MAX700/MAX701/MAX702 are guaranteed to be in
the correct state for V
CC
voltages down to +1V (Figure 4).
They provide excellent circuit reliability and low cost by
eliminating external components and adjustments when
used with +5V-powered circuits.
The MAX702 is the simplest part in the family. When
V
CC
falls to 4.65V,
RESET
goes low. The MAX702 also
provides a debounced manual reset input. The
MAX701 performs the same functions but has both
RESET
and RESET outputs. Their primary function is to
provide a system reset. Accordingly, an active reset
signal is supplied for low supply voltages and for at
least 200ms after the supply voltage reaches its operat-
ing value.
In addition to the features of the MAX701 and MAX702,
the MAX700 provides preset or adjustable voltage
detection so thresholds other than 4.65V can be select-
ed, and adjustable hysteresis. All parts are supplied in
8-pin PDIP and Narrow SO packages in commercial
and extended temperature ranges.
Features
♦
Min 200ms
RESET
Pulse on Power-Up, Power-
Down, and During Low-Voltage Conditions
♦
Reset Threshold Factory Trimmed for +5V
Systems
♦
No External Components or Adjustments with
+5V-Powered Circuits
♦
Debounced Manual Reset Input
♦
Preset or Adjustable Voltage Detection (MAX700)
♦
Adjustable Hysteresis (MAX700)
♦
8-Pin PDIP and Narrow SO Packages
MAX700/MAX701/MAX702
Ordering Information
PART*
MAX700C/D
MAX700CPA
MAX700CSA
MAX700EPA
MAX700ESA
MAX701C/D
MAX701CPA
MAX701CSA
MAX701EPA
MAX701ESA
MAX702C/D
MAX702CPA
MAX702CSA
MAX702EPA
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
Dice
8 PDIP
8 Narrow SO
8 PDIP
8 Narrow SO
Dice
8 PDIP
8 Narrow SO
8 PDIP
8 Narrow SO
Dice
8 PDIP
8 Narrow SO
8 PDIP
Applications
Computers
Controllers
Intelligent Instruments
Automotive Systems
Critical µP Power Monitoring
MAX702ESA
-40°C to +85°C
8 Narrow SO
*Devices
in PDIP and SO packages are available in both lead-
ed and lead-free packaging. Specify lead free by adding the +
symbol at the end of the part number when ordering.
Pin Configurations
TOP VIEW
MR 1
SENSE 2
8
7
V
CC
CTL
RESET
RESET
MR 1
N.C. 2
8
7
V
CC
N.C.
RESET
RESET
MR
V
CC
GND
1
2
8
7
N.C.
RESET
N.C.
N.C.
MAX700
HYST
3
6
5
N.C.
3
GND 4
GND 4
MAX701
6
5
MAX702
3
6
5
N.C. 4
DIP/SO
DIP/SO
DIP/SO
1
________________________________________________________________
Maxim Integrated Products
For pricing delivery, and ordering information please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Power-Supply Monitor with Reset
MAX700/MAX701/MAX702
ABSOLUTE MAXIMUM RATINGS
V
CC
......................................................................-0.3V to +15.5V
Voltage (with respect to GND) at RESET,
RESET,
HYST, CTL, SENSE ............................................-0.3V to V
CC
Operating Temperature Range
C Suffix .............................................................0°C to +70°C
E Suffix...........................................................-40°C to +85°C
Rate of Rise, V
CC
............................................................100V/µs
Power Dissipation, Any Package .....................................380mW
Storage Temperature Range .............................-55°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
= +5V, CTL = GND on MAX700, T
A
= +25°C, unless otherwise noted.)
PARAMETER
V
CC
Monitor Voltage Range
(MAX700 Only)
Min V
CC
for Valid Reset Output,
Declining Supply
Supply Current
Reset Threshold
Internal Hysteresis
Reset Output Pulse Width
RESET Fall Time
V
CC
Pulse Duration Guaranteeing
MR Input Threshold
MR Pullup Current
MAX700
RESET Output Low
I
SINK
= 3.2mA, V
CC
= 5V
I
SINK
= 1.6mA, V
CC
= 3V
I
SOURCE
= 3.2mA, V
CC
= 4.25V
RESET Output High
I
SOURCE
= 1.6mA, V
CC
= 3V
I
SOURCE
= 0.5mA, V
CC
= 1.5V
I
SINK
= 16mA, V
CC
= 4.25V
RESET
Output Low
I
SINK
= 1.6mA, V
CC
= 3V
I
SINK
= 0.4mA, V
CC
= 1.5V
I
SOURCE
= 3.2mA, V
CC
= 5V
RESET
Output High
I
SOURCE
= 1.6mA, V
CC
= 3V
V
CC
-
0.4
V
V
CC
-
0.4
V
CC
-
0.4
V
CC
-
0.4
V
CC
-
0.4
0.4
0.4
0.4
V
V
0.4
0.4
V
MAX700/MAX701 only, C
LOAD
= 100pF
5V to 4V V
CC
pulse
No reset
Reset
100
T
A
= T
MIN
to T
MAX
HYST not connected
200
Power-up
Power-down
4.50
4.50
CONDITIONS
T
A
= T
MIN
to T
MAX
, CTL = V
CC
T
A
= T
MIN
to T
MAX
,
RESET
≤
0.4V when sinking 1mA
MIN
3
1.5
1
100
4.65
4.62
30
350
200
10
10
0.7
-5
-30
1
500
200
4.75
4.75
TYP
MAX
15
UNITS
V
V
µA
V
mV
ms
ns
µs
V
µA
2
_______________________________________________________________________________________
Power-Supply Monitor with Reset
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +5V, CTL = GND on MAX700, T
A
= +25°C, unless otherwise noted.)
PARAMETER
MAX701
RESET Output Low
I
SINK
= 16mA, V
CC
= 5V
I
SOURCE
= 3.2mA, V
CC
= 4.25V
RESET Output High
I
SOURCE
= 1.6mA, V
CC
= 3V
I
SOURCE
= 0.5mA, V
CC
= 1.5V
I
SINK
= 3.2mA, V
CC
= 4.25V
RESET
Output Low
I
SINK
= 1.6mA, V
CC
= 3V
I
SINK
= 0.4mA, V
CC
= 1.5V
RESET
Output High
MAX702
I
SINK
= 3.2mA, V
CC
= 4.25V
RESET
Output Low
I
SINK
= 1.6mA, V
CC
= 3V
I
SINK
= 0.4mA, V
CC
= 1.5V
RESET
Output High
I
SOURCE
= 3.2mA, V
CC
= 5V
V
CC
-
0.4
1.25
1.29
0.1
0.5
2
30
100
1.35
0.4
0.4
0.4
V
V
I
SOURCE
= 3.2mA, V
CC
= 5V
V
CC
-
0.4
V
CC
-
0.4
V
CC
-
0.4
V
CC
-
0.4
0.4
0.4
0.4
V
V
V
0.4
V
CONDITIONS
MIN
TYP
MAX
UNITS
MAX700/MAX701/MAX702
MAX700 ONLY (CTL = V
CC
, unless otherwise noted)
SENSE Input Threshold
SENSE Input Current
HYST Input On-Resistance
CTL Input Threshold
CTL Pulldown Current
T
A
= T
MIN
to T
MAX
V
nA
kΩ
V
µA
_______________________________________________________________________________________
3
Power-Supply Monitor with Reset
MAX700/MAX701/MAX702
Pin Description
PIN
MAX700
1
MAX701
1
MAX702
1
NAME
MR
FUNCTION
Input for Manual Pushbutton Reset. Has internal 5µA pullup. Low input activates the
RESET/RESET outputs.
The voltage-sense input when CTL = V
CC
. Its threshold is 1.29V. SENSE always
remains connected to the internal comparator. So, when V
CC
is being monitored
internally (CTL = GND), SENSE should be left open circuit.
Normally NOT used when voltage is monitored through V
CC
(CTL = GND). When
monitoring through SENSE (CTL = V
CC
), HYST allows hysteresis to be added,
reducing noise and spurious reset activity (Figure 3). HYST turns on 5µs before the
RESET/RESET outputs are activated, and its on-resistance to GND is typically 1kΩ.
Ground
Goes low when V
CC
falls below 4.65V, or when CTL = V
CC
on the MAX700 goes low
when SENSE falls below 1.29V.
Inverted Version of
RESET
When CTL = GND, V
CC
is monitored by the reset circuit. When CTL = V
CC
, V
CC
is ignored
and SENSE is monitored, allowing the threshold to be set with external resistors.
Chip Power and +5V Sensing Input (When CTL = GND on MAX700)
No Connection
2
—
—
SENSE
3
—
—
HYST
4
5
6
7
8
—
4
6
5
—
8
2, 3, 7
3
7
—
—
2
4, 5, 6, 8
GND
RESET
RESET
CTL
V
CC
N.C.
4
_______________________________________________________________________________________
Power-Supply Monitor with Reset
MAX700/MAX701/MAX702
MR
1
1MΩ
8
V
CC
7
COMPARATOR
SENSE
2
150kΩ
CTL
MANUAL
RESET
BUTTON
1
N.C.
2
3
MR
SENSE
HYST
GND
MAX700
V
CC
CTL
RESET
RESET
8
7
6
5
+5V
MAX700
1.29V REF
R
RC
6
R OSC
HYST
3
5
4
RESET
RESET
N.C.
TO
µP
4
GND
Figure 1. MAX700 Block Diagram
Figure 2. MAX700 Typical Connection Diagram
MANUAL
RESET
BUTTON
1
R1
V
IN
R2
R3
3
4
HYST
GND
RESET
RESET
6
5
N.C.
TO
µP
2
MR
SENSE
MAX700
V
CC
CTL
8
7
V
IN
3V TO 15V
RESET
2V/div
0V
V
CC
R1 = R2
V
L
- 1 V
L
= LOWER VOLTAGE THRESHOLD
1.29
V
T
R1
R3 =
V = UPPER VOLTAGE THRESHOLD
V
U
- V
L U
2V/div
(
)
0V
1s/div
HYSTERESIS = V
U
- V
L
Figure 3. MAX700 Connected for External Senses and
Hysteresis
Figure 4. Typical MAX700/MAX701/MAX702 RESET Output vs. V
CC
Figure 4 shows the
RESET
output of the MAX700/
MAX701/MAX702 in the correct state for V
CC
voltages
down to 0V. Note the effect of the built-in hysteresis on
the trigger lever of
RESET.
Package Information
For the latest package outline information, go to
www.maxim-ic.com/packages.
_______________________________________________________________________________________
5
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