Semiconductor Components Industries, LLC, 2001
January, 2001 – Rev. 3 1Publication Order Number:
MAX811/D
MAX811, MAX812
4-Pin µP Reset Monitors
The MAX811 and MAX812 are cost–effective system supervisor
circuits designed to monitor VCC in digital systems and provide a reset
signal to the host processor when necessary. A manual reset input is
provided to override the reset monitor, and is suitable for use as a
push–button reset. No external components are required.
The reset output is driven active within 20 µsec (4 µsec for
F version) of VCC falling through the reset voltage threshold. RESET
is maintained active for a minimum of 140 msec after VCC rises above
the reset threshold. The MAX812 has an active–high RESET output
while the MAX811 has an active–low RESET output. The output of
the MAX811 is guaranteed valid down to VCC = 1 V. Both devices are
available in a 4–Pin SOT–143 package.
The MAX811/12 are optimized to reject fast transient glitches on
the VCC line. Low supply current of 7 µA (VCC = 3.3 V) makes these
devices suitable for battery powered applications.
Features
•Precision VCC Monitor for 1.8 V, 2.7 V, 3.0 V, 3.3 V, 5.0 V
Nominal Supplies
•Manual Reset Input
•140 msec Guaranteed Minimum RESET, RESET Output Duration
•RESET Output Guaranteed to VCC = 1.0 V (MAX811)
•Low 7 µA Supply Current
•VCC Transient Immunity
•Small SOT–143–4 Package
•No External Components
Typical Applications
•Computers
•Embedded Systems
•Battery Powered Equipment
•Critical µP Power Supply Monitoring
Typical Operating Circuit
GND
MAX811
PUSH–
VCC
RESET
MR
BUTTON
VCC
RESET
INPUT
(ACTIVE LOW)
GND
PROCESSOR
VCC
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PIN CONNECTIONS
1
GND 4VCC
2
MAX811 (RESET)3MR
MAX812 (RESET)
SOT–143
CASE 318A
12
3
4
See detailed ordering and shipping information in the package
dimensions section on page 6 of this data sheet.
ORDERING INFORMATION
See general marking information in the device marking
section on page 6 of this data sheet.
DEVICE MARKING INFORMATION
MAX811, MAX812
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2
ABSOLUTE MAXIMUM RATINGS*
Rating Symbol Value Unit
Supply Voltage (VCC to GND) – +6.0 V
RESET, RESET ––0.3 to (VCC +0.3) V
Input Current, VCC – 20 mA
Output Current, RESET, RESET – 20 mA
Operating Temperature Range TA–40 to +85 °C
Storage Temperature Range Tstg –65 to +150 °C
Lead Temperature (Soldering, 10 sec) – +260 °C
*This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational
sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may af fect device reliability.
ELECTRICAL CHARACTERISTICS (VCC = 5 V for L/M versions, VCC = 3.3 V for T/S versions, VCC = 3 V for R version,
VCC = 2.0 V for F version. TA = –40°C to +85°C unless otherwise noted. Typical values are at TA = +25°C.) (Note 1.)
Characteristics Test Conditions Symbol Min Typ Max Unit
VCC Range – VCC 1.2 – 5.5 V
Supply Current VCC VTH, for L, M, R, S, T, F
VCC VTH, for L, M, R, S, T
VCC VTH, for F
ICC –
–
–
7.0
10
6.0
15
15
12
µA
Reset Threshold MAX81_L: TA = +25°C
TA = –40°C to +85°C
MAX81_M: TA = +25°C
TA = –40°C to +85°C
MAX81_T: TA = +25°C
TA = –40°C to +85°C
MAX81_S: TA = +25°C
TA = –40°C to +85°C
MAX81_R: TA = +25°C
TA = –40°C to +85°C
MAX81_F: TA = +25°C
TA = –40°C to +85°C
VTH 4.54
4.50
4.30
4.25
3.03
3.00
2.88
2.85
2.58
2.55
1.71
1.70
4.63
–
4.38
–
3.08
–
2.93
–
2.63
–
1.75
–
4.72
4.75
4.46
4.50
3.14
3.15
2.98
3.00
2.68
2.70
1.79
1.80
V
Reset Threshold Tempco – – – 30 – ppm/°C
VCC to Reset Delay VCC = VTH to VTH –125 mV ;
L, M, R, S, T, F – –
–20
5.0 –
–µsec
Reset Active Timeout Period VCC = VTH(MAX) tRP 140 280 560 msec
MR Minimum Pulse Width – tMR 10 – – µsec
MR Glitch Immunity – – – 0.1 – µsec
MR to Reset Propagation Delay – tMD – 0.5 – µsec
MR Input Threshold VCC VTH(MAX),
MAX81_L/M VIH
VIL 2.3
––
––
0.8 V
– VCC VTH(MAX),
MAX81_R/S/T/F VIH
VIL 0.7 VCC
––
––
0.15 VCC V
MR Pull–up Resistance – – 10 20 40 KΩ
RESET Output Voltage High
(MAX812) ISOURCE = 150 µA;
VCC VTH(MIN) VOH 0.8 VCC – – V
1. Production testing done at TA = +25°C, over temperature limits guaranteed by design.
MAX811, MAX812
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ELECTRICAL CHARACTERISTICS (continued) (VCC = 5 V for L/M versions, VCC = 3.3 V for T/S versions, VCC = 3 V for R version,
VCC = 2. 0 V for F version. TA = –40°C to +85°C unless otherwise noted. Typical values are at TA = +25°C.) (Note 1.)
Characteristics Symbol Test Conditions Min Typ Max Unit
RESET Output Voltage Low
(MAX812) VOL MAX812F only, ISINK = 500 µA,
VCC = VTH(MAX)
MAX812R/S/T only, ISINK = 1.2 mA,
VCC = VTH(MAX)
MAX812L/M only, ISINK = 3.2 mA,
VCC = VTH(MAX)
–
–
–
–
–
–
0.2
0.3
0.4
V
RESET Output Voltage Low
(MAX811) VOL MAX811R/S/T only, ISINK = 1.2 mA,
VCC = VTH(MIN)
MAX811F only, ISINK = 500 µA,
VCC = VTH(MIN)
MAX811L/M only, ISINK = 3.2 mA,
VCC = VTH(MIN)
ISINK = 50 µA, VCC 1.0 V
–
–
–
–
–
–
0.3
0.4
TBD
V
RESET Output Voltage High
(MAX811) VOH MAX811L/M only,
ISOURCE = 800 µA,
VCC VTH(MAX)
MAX811R/S/T/F only,
ISOURCE = 500 µA,
VCC VTH(MAX)
VCC –1.5
0.8 VCC
–
–
–
–
V
1. Production testing done at TA = +25°C, over temperature limits guaranteed by design.
2. RESET output for MAX811, RESET output for MAX812.
PIN DESCRIPTION
Pin
Number Symbol Description
1 GND Ground
2 RESET (MAX811) RESET output remains low while VCC is below the reset voltage threshold, and for at least
140 msec min. after VCC rises above reset threshold.
2RESET (MAX812) RESET output remains high while VCC is below the reset voltage threshold, and for at least
140 msec min. after VCC rises above reset threshold.
3 MR Manual Reset input generates a reset when MR is below VIL.
4 VCC Supply voltage
MAX811, MAX812
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APPLICATIONS INFORMATION
VCC Transient Rejection
The MAX811/12 provides accurate VCC monitoring and
reset timing during power–up, power–down, and
brownout/sag conditions, and rejects negative–going
transients (glitches) on the power supply line. Figure 1
shows the maximum transient duration vs. maximum
negative excursion (overdrive) for glitch rejection. Any
combination of duration and overdrive that lays under the
curve will not generate a reset signal. Combinations above
the curve are detected as a brownout or power–down.
Transient immunity can be improved by adding a capacitor
in close proximity to the VCC pin of the MAX811/12.
Figure 1. Maximum Transient Duration vs.
Overdrive for Glitch Rejection at 25°C
MAXIMUM
TRANSIENT
DURATION
(
sec
)
Reset Comparator Overdrive, [VCCTP–VCC](mV)
400
320
240
160
80
0
TA = +25°C
1 5 100 1000
MAX811/12
Duration
VCC
VTH
Overdrive
RESET Signal Integrity During Power–Down
The MAX811 RESET output is valid to VCC = 1.0 V.
Below this voltage the output becomes an “open circuit’’ and
does not sink current. This means CMOS logic inputs to the
µP will be floating at an undetermined voltage. Most digital
systems are completely shutdown well above this voltage.
However, in situations where RESET must be maintained
valid to V CC = 0 V, a pull–down resistor must be connected
from RESET to ground to discharge stray capacitances and
hold the output low (Figure 2). This resistor value, though
not critical, should be chosen such that it does not
appreciably load RESET under normal operation (100 kΩ
will be suitable for most applications). Similarly, a pull–up
resistor t o V CC is required for the MAX812 to ensure a valid
high RESET for VCC below 1.1 V.
Figure 2. Ensuring RESET Valid to VCC = 0 V
VCC
GND
VCC
MAX811
RESET
R1
100 K
Processors with Bidirectional I/O Pins
Some µP’s (such as Motorola’s 68HC11) have
bi–directional reset pins. Depending on the current drive
capability of the processor pin, an indeterminate logic level
may result if there is a logic conflict. This can be avoided by
adding a 4.7 kΩ resistor in series with the output of the
MAX811/12 (Figure 3). If there are other components in the
system which require a reset signal, they should be buffered
so as not to load the reset line. If the other components are
required to follow the reset I/O of the µP, the buffer should
be connected as shown with the solid line.
Figure 3. Interfacing to Bidirectional Reset I/O
GND
MAX811
VCC
RESET
VCC
RESET
GND
VCC
BUFFER
4.7 K P
BUFFERED
RESET TO
OTHER
SYSTEM
COMPONENTS
MAX811, MAX812
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TYPICAL CHARACTERISTICS
POWER–DOWN RESET DELAY ( )
14
12
10
8
6
4
2
0
–40 –20 0 20 40 60 85
8
6
4
2
0–40 –20 0 20 40 60 85
–40 –20 0 20 40 60 85 –40 –20 0 20 40 60 85
–40 –20 0 20 40 60 85 –40 –15 10 35 60 65
50
40
30
20
10
0
50
40
30
20
10
0
245
240
235
230
225
250
Temperature (°C) Temperature (°C)
Temperature (°C) Temperature (°C)
Temperature (°C) Temperature (°C)
SUPPLY CURRENT (
POWER–UP RESET TIMEOUT (msec)
NORMALIZED THRESHOLD (V) A)
SUPPLY CURRENT (A)
1.003
1.002
1.001
1.000
0.999
0.998
0.997
0.996
0.994
0.995
MAX81xL/M
MAX81xR/S/T/F
VOD = 20 mV
VOD = 100 mV
VOD = 200 mV VOD = 200 mV
VOD = 100 mV VOD = 20 mV
VOD = 200 mV
VOD = 100 mV
VOD = 20 mV
L/M
R/S/T
VCC = 3 V
VCC = 5 V
VCC = 1 V
VCC = 5 V
VCC = 3 V
VCC = 1 V
sec
POWER–DOWN RESET DELAY ( )sec
Figure 4. Supply Current vs. Temperature
(No Load, MAX81xR/S/T/F) Figure 5. Supply Current vs. Temperature
(No Load, MAX81xL/M)
Figure 6. Power–Down Reset Delay vs.
Temperature (MAX81xF) Figure 7. Power–Down Reset Delay vs.
Temperature (MAX81xL/M/R/S/T)
Figure 8. Power–Up Reset Timeout vs.
Temperature Figure 9. Normalized Reset Threshold vs.
Temperature
MAX811, MAX812
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and = Part Number Code and
Temperature Range (two–digit code)
= Year and Quarter Code
= Lot ID Number
MARKING DIAGRAM
123 4
12
3
4
ORDERING INFORMATION
Device Threshold
Voltage Marking
and
12 Package
(Qty/Reel)
MAX811LEUS–T* 4.63 S1
MAX811MEUS–T* 4.38 S2
MAX811TEUS–T 3.08 S3
MAX811SEUS–T* 2.93 S4
MAX811REUS–T* 2.63 S5
MAX811FEUS–T 1.75 S7
3000 Units Tape and Reel
MAX812LEUS–T* 4.63 T1 3000 Units Tape and Reel
MAX812MEUS–T* 4.38 T2
MAX812TEUS–T 3.08 T3
MAX812SEUS–T* 2.93 T4
MAX812REUS–T* 2.63 T5
MAX812FEUS–T 1.75 T7
*Default: Contact your ON Semiconductor sales representative for other threshold voltage options.
MAX811, MAX812
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7
PACKAGE DIMENSIONS
SOT–143
CASE 318A–05
ISSUE R
DIM
A
MIN MAX MIN MAX
INCHES
2.80 3.04 0.110 0.120
MILLIMETERS
B1.20 1.39 0.047 0.055
C0.84 1.14 0.033 0.045
D0.39 0.50 0.015 0.020
F0.79 0.93 0.031 0.037
G1.78 2.03 0.070 0.080
H0.013 0.10 0.0005 0.004
J0.08 0.15 0.003 0.006
K0.46 0.60 0.018 0.024
L0.445 0.60 0.0175 0.024
R0.72 0.83 0.028 0.033
S2.11 2.48 0.083 0.098
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
G
S
R
CJ
A
L
FD
B
1
34
2
H
K
MAX811, MAX812
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without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular
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including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or
specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be
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For additional information, please contact your local
Sales Representative.
MAX811/D
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P.O. Box 5163, Denver, Colorado 80217 USA
Phone: 303–675–2175 or 800–344–3860 Toll Free USA/Canada
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