General Description
The MAX803/MAX809/MAX810 are microprocessor (μP)
supervisory circuits used to monitor the power supplies
in μP and digital systems. They provide excellent circuit
reliability and low cost by eliminating external components
and adjustments when used with +5V, +3.3V, +3.0V, or
+2.5V powered circuits.
These circuits perform a single function: they assert a
reset signal whenever the VCC supply voltage declines
below a preset threshold, keeping it asserted for at least
140ms after VCC has risen above the reset threshold.
Reset thresholds suitable for operation with a variety of
supply voltages are available.
The MAX803 has an open-drain output stage, while the
MAX809/MAX810 have push-pull outputs. The MAX803’s
open-drain RESET output requires a pullup resistor that
can be connected to a voltage higher than VCC. The
MAX803/MAX809 have an active-low RESET output,
while the MAX810 has an active-high RESET output. The
reset comparator is designed to ignore fast transients on
VCC, and the outputs are guaranteed to be in the correct
logic state for VCC down to 1V.
Low supply current makes the MAX803/MAX809/MAX810
ideal for use in portable equipment. The MAX803 is
available in a 3-pin SC70 package, and the MAX809/
MAX810 are available in 3-pin SC70 or SOT23 packages.
Applications
Computers
Controllers
Intelligent Instruments
Critical μP and μC Power Monitoring
Portable/Battery-Powered Equipment
Automotive
Benets and Features
Precision Monitoring of +2.5V, +3V, +3.3V, and
+5V Power-Supply Voltages
Fully Specified Over Temperature
Available in Three Output Configurations
Open-Drain RESET Output (MAX803)
Push-Pull RESET Output (MAX809)
Push-Pull RESET Output (MAX810)
140ms (min) Power-On-Reset Pulse Width
12μA Supply Current
Guaranteed Reset Valid to VCC = +1V
Power Supply Transient Immunity
No External Components
3-Pin SC70 and SOT23 Packages
19-0344; Rev 10; 12/15
MAX803
MAX809
VCC
VCC
RPULLUP*
RESET RESET
INPUT
GND
VCC
GND
*MAX803 ONLY
µP
Selector Guide and Ordering Information appear at end of data
sheet.
MAX803/MAX809/
MAX810
3-Pin Microprocessor Reset Circuits
Typical Operating Circuit
Terminal Voltage (with respect to GND)
VCC ...................................................................-0.3V to +6.0V
RESET, RESET (push-pull) .................. -0.3V to (VCC + 0.3V)
RESET (open drain) .........................................-0.3V to +6.0V
Input Current, VCC .............................................................20mA
Output Current, RESET, RESET ........................................20mA
Rate of Rise, VCC ..........................................................100V/μs
Continuous Power Dissipation (TA = +70°C)
3-Pin SC70 (derate 2.17mW/°C above +70°C) ...........174mW
3-Pin SOT23 (derate 4mW/°C above +70°C) .............320mW
Operating Temperature Range
3-Pin SC70 ................................................... -40°C to +125°C
3-Pin SOT23 ................................................. -40°C to +105°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
(VCC = full range, TA = -40°C to +105°C (SOT23) or TA = -40°C to +125°C (SC70), unless otherwise noted. Typical values are at TA =
+25°C, VCC = 5V for L/M/J versions, VCC = 3.3V for T/S versions, VCC = 3V for R version, and VCC = 2.5V for Z version.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
VCC Range
TA = 0°C to +70°C 1.0 5.5
VTA = -40°C to +105°C (MAX8_ _ _EUR) 1.2 5.5
TA = -40°C to +125°C (MAX8_ _ _EXR) 1.2 5.5
Supply Current (SOT23) ICC
TA = -40°C
to +85°C
VCC < 5.5V, MAX8_ _L/M 24 60
µA
VCC < 3.6V, MAX8_ _R/S/T/Z 17 50
TA = +85°C
to +105°C
VCC < 5.5V, MAX8_ _L/M 100
VCC < 3.6V, MAX8_ _R/S/T/Z 100
Supply Current (SC70) ICC
TA = -40°C
to +85°C
VCC < 5.5V, MAX8_ _L/M 24 35
VCC < 3.6V, MAX8_ _R/S/T/Z 17 30
TA = +85°C
to +125°C
VCC < 5.5V, MAX8_ _L/M 60
VCC < 3.6V, MAX8_ _R/S/T/Z 60
Reset Threshold
(SOT only) VTH
MAX8_ _L
TA = +25°C 4.56 4.63 4.70
V
TA = -40°C to +85°C 4.50 4.75
TA = -40°C to +125°C 4.40 4.86
MAX8_ _M
TA = +25°C 4.31 4.38 4.45
TA = -40°C to +85°C 4.25 4.50
TA = -40°C to +125°C 4.16 4.56
MAX809J
(SOT only)
TA = +25°C 3.93 4.00 4.06
TA = -40°C to +85°C 3.89 4.10
TA = -40°C to +125°C 3.80 4.20
MAX8_ _T
TA = +25°C 3.04 3.08 3.11
TA = -40°C to +85°C 3.00 3.15
TA = -40°C to +125°C 2.92 3.23
MAX8_ _S
TA = +25°C 2.89 2.93 2.96
TA = -40°C to +85°C 2.85 3.00
TA = -40°C to +125°C 2.78 3.08
MAX8_ _R
TA = +25°C 2.59 2.63 2.66
TA = -40°C to +85°C 2.55 2.70
TA = -40°C to +125°C 2.50 2.76
MAX803/MAX809/
MAX810
3-Pin Microprocessor Reset Circuits
www.maximintegrated.com Maxim Integrated
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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.
Electrical Characteristics
(VCC = full range, TA = -40°C to +105°C (SOT23) or TA = -40°C to +125°C (SC70), unless otherwise noted. Typical values are at TA =
+25°C, VCC = 5V for L/M/J versions, VCC = 3.3V for T/S versions, VCC = 3V for R version, and VCC = 2.5V for Z version.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Reset Threshold
(SC70 only) VTH
MAX8_ _L
TA = +25°C 4.56 4.63 4.70
V
TA = -40°C to +85°C 4.50 4.75
TA = -40°C to +125°C 4.44 4.82
MAX8_ _M
TA = +25°C 4.31 4.38 4.45
TA = -40°C to +85°C 4.25 4.50
TA = -40°C to +125°C 4.20 4.56
MAX8_ _T
TA = +25°C 3.04 3.08 3.11
TA = -40°C to +85°C 3.00 3.15
TA = -40°C to +125°C 2.95 3.21
MAX8_ _S
TA = +25°C 2.89 2.93 2.96
TA = -40°C to +85°C 2.85 3.00
TA = -40°C to +125°C 2.81 3.05
MAX8_ _R
TA = +25°C 2.59 2.63 2.66
TA = -40°C to +85°C 2.55 2.70
TA = -40°C to +125°C 2.52 2.74
MAX8_ _Z
(SC70 only)
TA = +25°C 2.28 2.32 2.35
TA = -40°C to +85°C 2.25 2.38
TA = -40°C to +125°C 2.22 2.42
Reset Threshold Tempco 30 ppm/°C
VCC to Reset Delay (Note 2) VCC = VTH to (VTH - 100mV) 20 µs
Reset Active Timeout Period
(SOT23)
TA = -40°C to +85°C 140 240 560 ms
TA = +85°C to +105°C 100 840
Reset Active Timeout Period
(SC70)
TA = -40°C to +85°C 140 240 460 ms
TA = +85°C to +125°C 100 840
RESET Output Voltage Low
(push-pull active low and open-
drain active low, MAX803 and
MAX809)
VOL
VCC = VTH (min), ISINK = 1.2mA,
MAX803R/S/T/Z, MAX809R/S/T/Z 0.3
V
VCC = VTH (min), ISINK = 3.2mA,
MAX803L/M, MAX809J/L/M 0.4
VCC > 1.0V, ISINK = 50µA 0.3
RESET Output Voltage High
(push-pull active low MAX809) VOH
VCC > VTH (max), ISOURCE = 500µA,
MAX803R/S/T/Z, MAX809R/S/T/Z 0.8VCC
V
VCC > VTH (max), ISOURCE = 800µA,
MAX803L/M, MAX809J/L/M VCC - 1.5
RESET Output Voltage Low
(push-pull active high, MAX810) VOL
VCC = VTH (max), ISINK = 1.2mA,
MAX810R/S/T/Z 0.3
V
VCC = VTH (max), ISINK = 3.2mA,
MAX810L/M 0.4
MAX803/MAX809/
MAX810
3-Pin Microprocessor Reset Circuits
www.maximintegrated.com Maxim Integrated
3
Electrical Characteristics (continued)
(VCC = full range, TA = -40°C to +105°C (SOT23) or TA = -40°C to +125°C (SC70), unless otherwise noted. Typical values are at TA =
+25°C, VCC = 5V for L/M/J versions, VCC = 3.3V for T/S versions, VCC = 3V for R version, and VCC = 2.5V for Z version.) (Note 1)
Note 1: Production testing done at TA = +25°C; limits over temperature guaranteed by design only.
Note 2: RESET output for MAX803/MAX809; RESET output for MAX810.
Note 3: Guaranteed by design, not production tested.
(VCC = full range, TA = -40°C to +105°C, unless otherwise noted. Typical values are at TA = +25°C, VCC = +5V for L/M/J versions,
VCC = +3.3V for T/S versions, VCC = +3V for R version, and VCC = +2.5V for Z version.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
RESET Output Voltage High
(push-pull active high, MAX810) VOH 1.8V < VCC < VTH (min), ISOURCE = 150µA 0.8VCC V
RESET Open-Drain Output
Leakage Current (MAX803)
(Note 3)
VCC > VTH, RESET deasserted 1 µA
0
POWER-DOWN RESET DELAY vs.
TEMPERATURE (MAX8_ _R/S/T/Z)
80
100
MAX803-TOC3
TEMPERATURE (°C)
POWER-DOWN RESET DELAY (µs)
40
20
60
-40 85
20
-20 060
40
VOD = VTH - VCC
VOD = 20mV
VOD = 10mV
VOD = 200mV
VOD = 100mV
0
POWER-DOWN RESET DELAY vs.
TEMPERATURE (MAX8_ _J/L/M)
80
100
120
140
MAX803-TOC4
TEMPERATURE (°C)
POWER-DOWN RESET DELAY (µs)
40
20
60
-40 85
20
-20 060
40
VOD = VTH - VCC
VOD = 10mV
VOD = 100mV
VOD = 200mV
VOD = 20mV
225
POWER-UP RESET TIMEOUT
vs. TEMPERATURE
245
250
MAX803-TOC5
TEMPERATURE (°C)
POWER-UP RESET TIMEOUT (µs)
235
230
240
-40 85
20
-20 060
40
MAX8_ _R/S/T/Z
MAX8_ _J/L/M
0.997
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE
1.001
1.002
1.003
MAX803-TOC6
TEMPERATURE (°C)
NORMALIZED THRESHOLD
0.999
0.998
1.000
-40 85
20
-20 060
40
-40 20 40-20 0 60 85
SUPPLY CURRENT vs. TEMPERATURE
(SC70 PACKAGE, NO LOAD)
MAX803 toc01
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
0
5
10
15
MAX8_ _R/S/T, VCC = 3.3V
MAX8_ _L/M/R/S/T/Z, VCC = 1V
MAX8_ _Z, VCC = 2.5V
MAX8_ _L/M, VCC = 5V
MAX803/MAX809/
MAX810
3-Pin Microprocessor Reset Circuits
www.maximintegrated.com Maxim Integrated
4
Electrical Characteristics (continued)
Typical Operating Characteristics
Detailed Description
A microprocessor’s (μP’s) reset input starts the μP in a
known state. The MAX803/MAX809/MAX810 assert reset
to prevent code-execution errors during power-up, power-
down, or brownout conditions. They assert a reset signal
whenever the VCC supply voltage declines below a preset
threshold, keeping it asserted for at least 140ms after VCC
has risen above the reset threshold. The MAX803 uses
an open-drain output, and the MAX809/MAX810 have a
push-pull output stage. Connect a pullup resistor on the
MAX803’s RESET output to any supply between 0 and 6V.
Applications Information
Negative-Going VCC Transients
In addition to issuing a reset to the μP during power-up,
power-down, and brownout conditions, the MAX803/
MAX809/MAX810 are relatively immune to short-duration
negative-going VCC transients (glitches).
Figure 1 shows typical transient duration vs. reset
comparator overdrive, for which the MAX803/MAX809/
MAX810 do not generate a reset pulse. The graph
was generated using a negative-going pulse applied
to VCC, starting 0.5V above the actual reset threshold
and ending below it by the magnitude indicated (reset
comparator overdrive). The graph indicates the maximum
pulse width a negative-going VCC transient can have with-
out causing a reset pulse. As the magnitude of the transient
increases (goes farther below the reset threshold), the
maximum allowable pulse width decreases. Typically, for
the MAX8__L and MAX8__M, a VCC transient that goes
100mV below the reset threshold and lasts 20μs or less will
not cause a reset pulse. A 0.1μF bypass capacitor mounted
as close as possible to the VCC pin provides additional
transient immunity.
Ensuring a Valid Reset Output Down to
VCC = 0V
When VCC falls below 1V, the MAX809 RESET output no
longer sinks current—it becomes an open circuit.
Therefore, high-impedance CMOS logic inputs connect-
ed to RESET can drift to undetermined voltages. This
presents no problem in most applications since most
μP and other circuitry is inoperative with VCC below 1V.
However, in applications where RESET must be valid
down to 0V, adding a pull-down resistor to RESET causes
any stray leakage currents to flow to ground, holding
RESET low (Figure 2). R1’s value is not critical; 100kΩ is
large enough not to load RESET and small enough to pull
RESET to ground.
A 100kΩ pullup resistor to VCC is also recommended for the
MAX810 if RESET is required to remain valid for VCC < 1V.
Interfacing to μPs with Bidirectional Reset
Pins
Since the RESET output on the MAX803 is open
drain, this device interfaces easily with μPs that have
bidirectional reset pins, such as the Motorola 68HC11.
Connecting the μP supervisors RESET output directly to
the μC’s RESET pin with a single pullup resistor allows
either device to assert reset (Figure 3).
MAX803 Open-Drain RESET Output Allows
Use with Multiple Supplies
Generally, the pullup connected to the MAX803 will
connect to the supply voltage that is being monitored at the
IC’s VCC pin. However, some systems may use the open-
drain output to level-shift from the monitored supply to reset
circuitry powered by some other supply (Figure 4). Note
that as the MAX803’s VCC decreases below 1V, so does
the IC’s ability to sink current at RESET. Also, with any
pullup, RESET will be pulled high as VCC decays toward
0. The voltage where this occurs depends on the pullup
resistor value and the voltage to which it is connected.
PIN NAME FUNCTION
1GND Ground
2
RESET
(MAX803/
MAX809)
RESET Output remains low while VCC
is below the reset threshold, and for at
least 140ms after VCC rises above the
reset threshold.
RESET
(MAX810)
RESET Output remains high while VCC
is below the reset threshold, and for at
least 140ms after VCC rises above the
reset threshold.
3 VCC Supply Voltage (+5V, +3.3V, +3.0V, or
+2.5V)
TOP VIEW
RESET (RESET)
1
GND
VCC
MAX803
MAX809
MAX810
SC70-3/SOT23-3
2
3
( ) ARE FOR MAX810.
MAX803 AVAILABLE IN SC70-3 ONLY.
MAX803/MAX809/
MAX810
3-Pin Microprocessor Reset Circuits
www.maximintegrated.com Maxim Integrated
5
Pin Description
Pin Conguration
Benets of Highly Accurate Reset Threshold
Most μP supervisor ICs have reset-threshold voltages
between 5% and 10% below the value of nominal supply
voltages. This ensures a reset will not occur within 5% of
the nominal supply, but will occur when the supply is 10%
below nominal.
When using ICs rated at only the nominal supply ±5%,
this leaves a zone of uncertainty where the supply is
between 5% and 10% low, and where the reset may or
may not be asserted.
The MAX8_ _L/T/Z use highly accurate circuitry to ensure
that reset is asserted close to the 5% limit, and long
before the supply has declined to 10% below nominal.
400
320
0
1 100 1000
160
80
240
RESET COMPARATOR OVERDRIVE, VTH - VCC (mV)
MAXIMUM TRANSIENT DURATION (µs)
10
TA = +25°C
MAX8_ _J/L/M
MAX8_ _R/S/T/Z
RESET
GND
RESET
INPUT
MAX803 MOTOROLA
68HCXX
µP
GND
VCC
VCC
VCC
R1
100k
VCC
GND
MAX809
RESET
RESET
GND
RESET
INPUT
RPULLUP
MAX803 5V SYSTEM
GND
VCC
+3.3V +5.0V
VCC
Figure 1. Maximum Transient Duration Without Causing a
Reset Pulse vs. Reset Comparator Overdrive
Figure 3. Interfacing to μPs with Bidirectional Reset I/O
Figure 2. RESET Valid to VCC = Ground Circuit
Figure 4. MAX803 Open-Drain RESET Output Allows Use with
Multiple Supplies
MAX803/MAX809/
MAX810
3-Pin Microprocessor Reset Circuits
www.maximintegrated.com Maxim Integrated
6
Note: These parts are offered in 2.5k reels, and must be
ordered in 2.5k increments. Insert the desired suffix letter from
the Selector Guide into the blank to complete the part number.
All versions of these products may not be available at the time
of announcement. Contact factory for availability.
Some devices are available in both leaded and lead-free packaging.
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
T = Tape and reel.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
3 SC70 X3+2, X3-2 21-0075
3 SOT23 U3+1, U3-1 21-0051
PART TEMP RANGE PIN-PACKAGE
MAX803_EXR-T -40ºC to +125ºC 3 SC70
MAX803_EXR+T -40ºC to +125ºC 3 SC70
MAX803_EXR/V+ -40ºC to +125ºC 3 SC70
MAX803_EXR/V+T -40ºC to +125ºC 3 SC70
MAX809_EXR-T -40ºC to +125ºC 3 SC70
MAX809_EXR+T -40ºC to +125ºC 3 SC70
MAX809_EUR-T -40ºC to +105ºC 3 SOT23
MAX809_EUR+T -40ºC to +105ºC 3 SOT23
MAX810_EXR+T -40ºC to +125ºC 3 SC70
MAX810_EUR+T -40ºC to +105ºC 3 SOT23
MAX803/MAX809/
MAX810
3-Pin Microprocessor Reset Circuits
www.maximintegrated.com Maxim Integrated
7
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages. Note
that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
Chip Information
TRANSISTOR COUNT: 275 (SOT23)
380 (SC70)
Ordering Information
Selector Guide
PART/SUFFIX RESET THRESHOLD (V) OUTPUT TYPE
MAX803L 4.63 Open-Drain RESET
MAX803M 4.38 Open-Drain RESET
MAX803T 3.08 Open-Drain RESET
MAX803S 2.93 Open-Drain RESET
MAX803R 2.63 Open-Drain RESET
MAX803Z 2.32 Open-Drain RESET
MAX809L 4.63 Push-Pull RESET
MAX809M 4.38 Push-Pull RESET
MAX809J 4.00 Push-Pull RESET
MAX809T 3.08 Push-Pull RESET
MAX809S 2.93 Push-Pull RESET
MAX809R 2.63 Push-Pull RESET
MAX809Z 2.32 Push-Pull RESET
MAX810L 4.63 Push-Pull RESET
MAX810M 4.38 Push-Pull RESET
MAX810T 3.08 Push-Pull RESET
MAX810S 2.93 Push-Pull RESET
MAX810R 2.63 Push-Pull RESET
MAX810Z 2.32 Push-Pull RESET
For top mark information, go to https://www.maximintegrated.com/en/design/packaging/topmark/.
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 12/94 Initial release.
72/10 Updated Ordering Information, added lead-free note, and added soldering temperature
in the Absolute Maximum Ratings 1, 2
8 12/12 Added MAX803_EXR/V+ to Ordering Information 1
96/15 Added MAX803_EXR/V+ to Ordering Information, moved Ordering Information, Pin
Conguration, and Selector Guide to end of data sheet, and rebranded data sheet 1–8
10 12/15 Added lead-free package code information and removed top mark information from
Selector Guide 7
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
MAX803/MAX809/
MAX810
3-Pin Microprocessor Reset Circuits
© 2015 Maxim Integrated Products, Inc.
8
Revision History
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