19-0344; Rev 4; 12/99
3-Pin Microprocessor Reset Circuits
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 compo-
nents 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 V
CC
supply voltage declines
below a preset threshold, keeping it asserted for at
least 140ms after V
CC
has risen above the reset thresh-
old. Reset thresholds suitable for operation with a vari-
ety 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 pull-up
resistor that can be connected to a voltage higher than
V
CC
. 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 V
CC
, and the outputs are guaranteed to
be in the correct logic state for V
CC
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.
____________________________Features
o
Precision Monitoring of +2.5V, +3V, +3.3V, and
+5V Power-Supply Voltages
o
Fully Specified Over Temperature
o
Available in Three Output Configurations
Open-Drain
RESET
Output (MAX803)
Push-Pull
RESET
Output (MAX809)
Push-Pull RESET Output (MAX810)
o
140ms min Power-On Reset Pulse Width
o
12µA Supply Current
o
Guaranteed Reset Valid to V
CC
= +1V
o
Power Supply Transient Immunity
o
No External Components
o
3-Pin SC70 and SOT23 Packages
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
Ordering Information
PART
MAX803_EXR-T
MAX803_EXR-T10
MAX809_EXR-T
MAX809_EXR-T10
MAX809_EUR-T
MAX809_EUR-T10
MAX810_EXR-T
MAX810_EXR-T10
MAX810_EUR-T
MAX810_EUR-T10
TEMP. RANGE
-40°C to +105°C
-40°C to +105°C
-40°C to +105°C
-40°C to +105°C
-40°C to +105°C
-40°C to +105°C
-40°C to +105°C
-40°C to +105°C
-40°C to +105°C
-40°C to +105°C
PIN-PACKAGE
3 SC70-3
3 SC70-3
3 SC70-3
3 SC70-3
3 SOT23-3
3 SOT23-3
3 SC70-3
3 SC70-3
3 SOT23-3
3 SOT23-3
Applications
Computers
Controllers
Intelligent Instruments
Critical µP and µC Power Monitoring
Portable/Battery-Powered Equipment
Automotive
Note:
These parts are offered in 2.5k or 10k reels, and must be
ordered in 2.5k or 10k increments. Order MAX803_EXR-T for
2.5k reels and MAX803_EXR-T10 for 10k reels. 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.
Typical Operating Circuit
TOP VIEW
V
CC
GND
1
V
CC
R
PULL-UP
*
V
CC
Pin Configuration
MAX803
MAX809
RESET
RESET
INPUT
µP
MAX803
MAX809
MAX810
3
V
CC
RESET (RESET)
2
GND
GND
( ) ARE FOR MAX810.
MAX803 AVAILABLE IN SC70-3 ONLY.
SC70-3/SOT23-3
*MAX803 ONLY
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
3-Pin Microprocessor Reset Circuits
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND)
V
CC
....................................................................-0.3V to +6.0V
RESET,
RESET
(push-pull) .....................-0.3V to (V
CC
+ 0.3V)
RESET
(open drain)...........................................-0.3V to +6.0V
Input Current, V
CC
..............................................................20mA
Output Current, RESET,
RESET
..........................................20mA
Rate of Rise, V
CC
............................................................100V/µs
Continuous Power Dissipation (T
A
= +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 .........................-40°C to +105°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
= full range, T
A
= -40°C to +105°C, unless otherwise noted. Typical values are at T
A
= +25°C, V
CC
= 5V for L/M/J versions, V
CC
= 3.3V for T/S versions, V
CC
= 3V for R version, and V
CC
= 2.5V for Z version.) (Note 1)
PARAMETER
V
CC
Range
SYMBOL
CONDITIONS
T
A
= 0°C to +70°C
T
A
= -40°C to +105°C
T
A
= -40°C to
+85°C
Supply Current (SOT23)
I
CC
T
A
= +85°C to
+105°C
T
A
= -40°C to
+85°C
Supply Current (SC70)
I
CC
T
A
= +85°C to
+105°C
MAX8_ _L
V
CC
< 5.5V, MAX8_ _J/L/M
V
CC
< 3.6V, MAX8_ _R/S/T
V
CC
< 5.5V, MAX8_ _L/M
V
CC
< 3.6V, MAX8_ _R/S/T
V
CC
< 5.5V, MAX8_ _L/M
V
CC
< 3.6V, MAX8_ _R/S/T/Z
V
CC
< 5.5V, MAX8_ _L/M
V
CC
< 3.6V, MAX8_ _R/S/T/Z
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +85°C to +105°C
T
A
= +25°C
MAX8_ _M
T
A
= -40°C to +85°C
T
A
= +85°C to +105°C
MAX809J
(SOT only)
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +85°C to +105°C
T
A
= +25°C
Reset Threshold
V
TH
MAX8_ _T
T
A
= -40°C to +85°C
T
A
= +85°C to +105°C
T
A
= +25°C
MAX8_ _S
T
A
= -40°C to +85°C
T
A
= +85°C to +105°C
T
A
= +25°C
MAX8_ _R
T
A
= -40°C to +85°C
T
A
= +85°C to +105°C
MAX8_ _Z
(SC70 only)
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +85°C to +105°C
2
4.56
4.50
4.40
4.31
4.25
4.16
3.93
3.89
3.80
3.04
3.00
2.92
2.89
2.85
2.78
2.59
2.55
2.50
2.28
2.25
2.21
2.32
2.63
2.93
3.08
4.00
4.38
4.63
16
12
MIN
1.0
1.2
24
17
TYP
MAX
5.5
5.5
60
50
100
100
35
30
75
75
4.70
4.75
4.86
4.45
4.50
4.56
4.06
4.10
4.20
3.11
3.15
3.23
2.96
3.00
3.08
2.66
2.70
2.76
2.35
2.38
2.45
V
µA
UNITS
V
_______________________________________________________________________________________
3-Pin Microprocessor Reset Circuits
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= full range, T
A
= -40°C to +105°C, unless otherwise noted. Typical values are at T
A
= +25°C, V
CC
= 5V for L/M/J versions, V
CC
= 3.3V for T/S versions, V
CC
= 3V for R version, and V
CC
= 2.5V for Z version.) (Note 1)
PARAMETER
Reset Threshold Tempco
V
CC
to Reset Delay (Note 2)
Reset Active Timeout Period
(SOT23)
Reset Active Timeout Period
(SC70)
RESET
Output Voltage Low
(push-pull active low and open-
drain active-low, MAX803 and
MAX809)
V
CC
= V
TH
to (V
TH
- 100mV)
T
A
= -40°C to +85°C
T
A
= +85°C to +105°C
T
A
= -40°C to +85°C
T
A
= +85°C to +105°C
V
CC
= V
TH
min, I
SINK
= 1.2mA,
MAX803R/S/T/Z, MAX809R/S/T/Z
V
OL
V
CC
= V
TH
min, I
SINK
= 3.2mA,
MAX803L/M, MAX809J/L/M
V
CC
> 1.0V, I
SINK
= 50µA
RESET
Output Voltage High
(push-pull active low, MAX809)
V
CC
> V
TH
max, I
SOURCE
= 500µA,
MAX809R/S/T/Z
V
OH
V
CC
> V
TH
max, I
SOURCE
= 800µA,
MAX809J/L/M
V
CC
= V
TH
max, I
SINK
= 1.2mA,
MAX810R/S/T/Z
V
OL
V
CC
= V
TH
max, I
SINK
= 3.2mA,
MAX810L/M
1.8V < V
CC
< V
TH
min, I
SOURCE
= 150µA
V
CC
> V
TH
,
RESET
deasserted
0.8V
CC
1
0.8V
CC
V
V
CC
- 1.5
0.3
V
0.4
V
µA
140
100
140
100
240
SYMBOL
CONDITIONS
MIN
TYP
30
20
240
560
840
460
840
0.3
0.4
0.3
V
MAX
UNITS
ppm/°C
µs
ms
ms
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
RESET Output Voltage Low
(push-pull active high, MAX810)
RESET Output Voltage High
(push-pull active high, MAX810)
RESET
Open-Drain Output
Leakage Current (MAX803)
V
OH
Note 1:
Production testing done at T
A
= +25°C; limits over temperature guaranteed by design only.
Note 2:
RESET
output for MAX803/MAX809; RESET output for MAX810.
Typical Operating Characteristics
(V
CC
= full range, T
A
= -40°C to +105°C, unless otherwise noted. Typical values are at T
A
= +25°C, V
CC
= +5V for L/M/J versions,
V
CC
= +3.3V for T/S versions, V
CC
= +3V for R version, and V
CC
= +2.5V for Z version.)
SUPPLY CURRENT vs. TEMPERATURE
(SC70 PACKAGE, NO LOAD)
MAX803 toc01
POWER-DOWN RESET DELAY vs.
TEMPERATURE (MAX8_ _R/S/T/Z)
V
OD
= V
TH
- V
CC
V
OD
= 10mV
MAX803-TOC3
15
100
POWER-DOWN RESET DELAY (µs)
MAX8_ _L/M, V
CC
= 5V
SUPPLY CURRENT (µA)
10
MAX8_ _R/S/T, V
CC
= 3.3V
MAX8_ _Z, V
CC
= 2.5V
5
80
60
V
OD
= 20mV
40
20
0
V
OD
= 100mV
V
OD
= 200mV
-40
-20
20
0
40
TEMPERATURE (°C)
60
85
MAX8_ _L/M/R/S/T/Z, V
CC
= 1V
0
-40
-20
0
20
40
60
85
TEMPERATURE (°C)
_______________________________________________________________________________________
40
3
3-Pin Microprocessor Reset Circuits
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
Typical Operating Characteristics (continued)
(V
CC
= full range, T
A
= -40°C to +105°C, unless otherwise noted. Typical values are at T
A
= +25°C, V
CC
= +5V for L/M/J versions,
V
CC
= +3.3V for T/S versions, V
CC
= +3V for R version, and V
CC
= +2.5V for Z version.)
POWER-DOWN RESET DELAY vs.
TEMPERATURE (MAX8_ _J/L/M)
MAX803-TOC4
POWER-UP RESET TIMEOUT
vs. TEMPERATURE
MAX803-TOC5
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE
MAX803-TOC6
140
POWER-DOWN RESET DELAY (µs)
120
100
80
60
40
20
0
-40
-20
V
OD
= V
TH
- V
CC
V
OD
= 10mV
250
POWER-UP RESET TIMEOUT (ms)
1.003
1.002
MAX8_ _J/L/M
240
MAX8_ _R/S/T/Z
235
NORMALIZED THRESHOLD
85
245
V
OD
= 20mV
1.001
1.000
0.999
0.998
0.997
V
OD
= 100mV
V
OD
= 200mV
20
0
40
TEMPERATURE (°C)
60
85
230
225
-40
-20
0
20
40
60
TEMPERATURE (°C)
-40
-20
0
20
40
60
85
TEMPERATURE (°C)
Selector Guide
PART/SUFFIX
MAX803L
MAX803M
MAX803T
MAX803S
MAX803R
MAX803Z
MAX809L
MAX809M
MAX809J
MAX809T
MAX809S
MAX809R
MAX809Z
MAX810L
MAX810M
MAX810T
MAX810S
MAX810R
MAX810Z
4
RESET THRESHOLD (V)
4.63
4.38
3.08
2.93
2.63
2.32
4.63
4.38
4.00
3.08
2.93
2.63
2.32
4.63
4.38
3.08
2.93
2.63
2.32
OUTPUT TYPE
Open-Drain
RESET
Open-Drain
RESET
Open-Drain
RESET
Open-Drain
RESET
Open-Drain
RESET
Open-Drain
RESET
Push-Pull RESET
Push-Pull RESET
Push-Pull RESET
Push-Pull RESET
Push-Pull RESET
Push-Pull RESET
Push-Pull RESET
Push-Pull RESET
Push-Pull RESET
Push-Pull RESET
Push-Pull RESET
Push-Pull RESET
Push-Pull RESET
TOP MARK
SOT
—
—
—
—
—
—
AAAA
ABAA
CWAA
ACAA
ADAA
AFAA
—
AGAA
AHAA
AJAA
AKAA
ALAA
—
SC70
AAZ
ABA
ABB
ABC
ABD
ABE
AAN
AAO
—
AAP
AAQ
AAR
AAS
AAT
AAU
AAV
AAX
AAW
AAY
_______________________________________________________________________________________
3-Pin Microprocessor Reset Circuits
_____________________Pin Description
PIN
1
NAME
GND
RESET
(MAX803/
MAX809)
2
RESET
(MAX810)
Ground
RESET
Output remains low while V
CC
is below the reset threshold, and for at
least 140ms after V
CC
rises above the
reset threshold.
RESET Output remains high while V
CC
is below the reset threshold, and for at
least 140ms after V
CC
rises above the
reset threshold.
Supply Voltage (+5V, +3.3V, +3.0V, or
+2.5V)
FUNCTION
V
CC
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
MAX809
RESET
R1
100k
GND
3
V
CC
Figure 2.
RESET
Valid to V
CC
= Ground Circuit
Applications Information
400
MAXIMUM TRANSIENT DURATION (µs)
T
A
= +25°C
320
Negative-Going V
CC
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 V
CC
transients (glitches).
Figure 1 shows typical transient duration vs. reset com-
parator overdrive, for which the MAX803/MAX809/
MAX810 do
not
generate a reset pulse. The graph was
generated using a negative-going pulse applied to V
CC
,
starting 0.5V above the actual reset threshold and end-
ing below it by the magnitude indicated (reset compara-
tor overdrive). The graph indicates the maximum pulse
width a negative-going V
CC
transient can have without
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 V
CC
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 V
CC
pin provides
additional transient immunity.
240
160
MAX8_ _J/L/M
80
MAX8_ _R/S/T/Z
0
1
10
100
1000
RESET COMPARATOR OVERDRIVE, V
TH
- V
CC
(mV)
Figure 1. Maximum Transient Duration Without Causing a
Reset Pulse vs. Reset Comparator Overdrive
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 V
CC
supply voltage declines
below a preset threshold, keeping it asserted for at
least 140ms after V
CC
has risen above the reset thresh-
old. The MAX803 uses an open-drain output, and the
MAX809/MAX810 have a push-pull output stage.
Connect a pull-up resistor on the MAX803’s
RESET
out-
put to any supply between 0 and 6V.
When V
CC
falls below 1V, the MAX809
RESET
output
no longer sinks current—it becomes an open circuit.
Therefore, high-impedance CMOS logic inputs con-
nected to
RESET
can drift to undetermined voltages.
This presents no problem in most applications since
most µP and other circuitry is inoperative with V
CC
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
5
Ensuring a Valid Reset Output
Down to V
CC
= 0
_______________________________________________________________________________________
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