General Description
The MAX803/MAX809/MAX810 are microprocessor (P)
supervisory circuits used to monitor the power supplies
in P 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.
Applications
Computers
Controllers
Intelligent Instruments
Critical P and C Power Monitoring
Portable/Battery-Powered Equipment
Automotive
____________________________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 12A 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
3-Pin Microprocessor Reset Circuits
________________________________________________________________ Maxim Integrated Products
1
TOP VIEW
RESET (RESET)
1
GND
V
CC
MAX803
MAX809
MAX810
SC70-3/SOT23-3
2
3
( ) ARE FOR MAX810.
MAX803 AVAILABLE IN SC70-3 ONLY.
MAX803
MAX809
V
CC
V
CC
R
PULL-UP
*
RESET
RESET
INPUT
GND
V
CC
GND
*MAX803 ONLY
P
Pin Configuration
Typical Operating Circuit
19-0344; Rev 4; 12/99
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.
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 SC70-3
-40C to +105C
MAX803_EXR-T10
3 SC70-3
PIN-PACKAGE
TEMP. RANGE
-40C to +105C
MAX803_EXR-T
PART
3 SC70-3
-40C to +105C
MAX809_EXR-T10
3 SC70-3
-40C to +105C
MAX809_EXR-T
3 SOT23-3
-40C to +105C
MAX809_EUR-T10
3 SOT23-3
-40C to +105C
MAX809_EUR-T
3 SC70-3
-40C to +105C
MAX810_EXR-T10
3 SC70-3
-40C to +105C
MAX810_EXR-T
3 SOT23-3
-40C to +105C
MAX810_EUR-T10
3 SOT23-3
-40C to +105C
MAX810_EUR-T
Ordering Information
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
3-Pin Microprocessor Reset Circuits
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
CC
= full range, T
A
= -40C to +105C, unless otherwise noted. Typical values are at T
A
= +25C, 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)
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.
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/s
Continuous Power Dissipation (T
A
= +70C)
3-Pin SC70 (derate 2.17mW/C above +70C) ............174mW
3-Pin SOT23 (derate 4mW/C above +70C)...............320mW
Operating Temperature Range .........................-40C to +105C
Storage Temperature Range .............................-65C to +150C
Lead Temperature (soldering, 10s) .................................+300C
T
A
= -40C to
+85C
T
A
= -40C to +105C
T
A
= 0C to +70C
T
A
= +85C to
+105C
MAX8_ _Z
(SC70 only)
T
A
= -40C to
+85C
V
CC
< 3.6V, MAX8_ _R/S/T
T
A
= +85C to
+105C
MAX8_ _L
CONDITIONS
2.21
2.45
2.25
2.38
2.28
2.32
2.35
2.50
2.76
4.50
4.75
V
4.56
4.63
4.70
V
TH
Reset Threshold
24
60
I
CC
Supply Current (SOT23)
1.2
5.5
V
1.0
5.5
V
CC
Range
A
75
75
12
30
16
35
I
CC
Supply Current (SC70)
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
17
50
100
100
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
V
CC
< 5.5V, MAX8_ _J/L/M
V
CC
< 5.5V, MAX8_ _L/M
MAX8_ _S
2.89
2.93
2.96
T
A
= +25C
V
CC
< 3.6V, MAX8_ _R/S/T/Z
T
A
= +25C
T
A
= -40C to +85C
MAX8_ _M
4.25
4.50
2.85
3.00
T
A
= -40C to +85C
MAX8_ _R
2.55
2.70
2.59
2.63
2.66
2.78
3.08
T
A
= +85C to +105C
T
A
= +25C
T
A
= -40C to +85C
4.31
4.38
4.45
4.40
4.86
T
A
= +85C to +105C
T
A
= +25C
T
A
= -40C to +85C
MAX809J
(SOT only)
3.93
4.00
4.06
4.16
4.56
T
A
= +85C to +105C
T
A
= +25C
3.89
4.10
T
A
= -40C to +85C
3.80
4.20
T
A
= +85C to +105C
MAX8_ _T
2.92
3.23
3.00
3.15
3.04 3.08
3.11
T
A
= +25C
T
A
= -40C to +85C
T
A
= +85C to +105C
T
A
= +85C to +105C
T
A
= +25C
T
A
= -40C to +85C
T
A
= +85C to +105C
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
3-Pin Microprocessor Reset Circuits
_______________________________________________________________________________________
3
Note 1: Production testing done at T
A
= +25C; limits over temperature guaranteed by design only.
Note 2: RESET output for MAX803/MAX809; RESET output for MAX810.
T
A
= -40C to +85C
T
A
= +85C to +105C
T
A
= -40C to +85C
V
CC
= V
TH
to (V
TH
- 100mV)
CONDITIONS
140
240
460
Reset Active Timeout Period
(SC70)
ms
100
840
140
240
560
Reset Active Timeout Period
(SOT23)
s
20
V
CC
to Reset Delay (Note 2)
ppm/C
30
Reset Threshold Tempco
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
T
A
= +85C to +105C
V
CC
= V
TH
max, I
SINK
= 3.2mA,
MAX810L/M
V
CC
= V
TH
max, I
SINK
= 1.2mA,
MAX810R/S/T/Z
V
CC
> V
TH
max, I
SOURCE
= 800A,
MAX809J/L/M
V
CC
> V
TH
max, I
SOURCE
= 500A,
MAX809R/S/T/Z
V
CC
= V
TH
min, I
SINK
= 1.2mA,
MAX803R/S/T/Z, MAX809R/S/T/Z
V
CC
= V
TH
min, I
SINK
= 3.2mA,
MAX803L/M, MAX809J/L/M
V
CC
> V
TH
, RESET deasserted
V
CC
> 1.0V, I
SINK
= 50A
1.8V < V
CC
< V
TH
min, I
SOURCE
= 150A
A
1
RESET Open-Drain Output
Leakage Current (MAX803)
V
0.8V
CC
V
OH
RESET Output Voltage High
(push-pull active high, MAX810)
ms
100
840
0.4
V
0.3
V
OL
RESET Output Voltage Low
(push-pull active high, MAX810)
V
CC
- 1.5
V
0.8V
CC
V
OH
RESET Output Voltage High
(push-pull active low, MAX809)
V
0.3
V
OL
RESET Output Voltage Low
(push-pull active low and open-
drain active-low, MAX803 and
MAX809)
0.4
0.3
0
POWER-DOWN RESET DELAY vs.
TEMPERATURE (MAX8_ _R/S/T/Z)
80
100
MAX803-TOC3
TEMPERATURE (C)
POWER-DOWN RESET DELAY (
s)
40
20
60
-40
85
20
-20
0
60
40
V
OD
= V
TH
- V
CC
V
OD
= 20mV
V
OD
= 10mV
V
OD
= 200mV
V
OD
= 100mV
Typical Operating Characteristics
(V
CC
= full range, T
A
= -40C to +105C, unless otherwise noted. Typical values are at T
A
= +25C, 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.)
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= full range, T
A
= -40C to +105C, unless otherwise noted. Typical values are at T
A
= +25C, 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)
-40
20
40
40
-20
0
60
85
SUPPLY CURRENT vs. TEMPERATURE
(SC70 PACKAGE, NO LOAD)
MAX803 toc01
TEMPERATURE (C)
SUPPLY CURRENT (
A)
0
5
10
15
MAX8_ _R/S/T, V
CC
= 3.3V
MAX8_ _L/M/R/S/T/Z, V
CC
= 1V
MAX8_ _Z, V
CC
= 2.5V
MAX8_ _L/M, V
CC
= 5V
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
3-Pin Microprocessor Reset Circuits
4
_______________________________________________________________________________________
Typical Operating Characteristics (continued)
(V
CC
= full range, T
A
= -40C to +105C, unless otherwise noted. Typical values are at T
A
= +25C, 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.)
225
POWER-UP RESET TIMEOUT
vs. TEMPERATURE
245
250
MAX803-TOC5
TEMPERATURE (C)
POWER-UP RESET TIMEOUT (ms)
235
230
240
-40
85
20
-20
0
60
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
0
60
40
3.08
MAX803T
4.38
4.63
MAX803L
MAX803M
2.93
MAX809S
3.08
MAX809T
4.00
MAX809J
Open-Drain RESET
Open-Drain RESET
4.38
MAX809M
Open-Drain RESET
Push-Pull RESET
2.93
MAX803S
Push-Pull RESET
Push-Pull RESET
2.63
MAX803R
Push-Pull RESET
Open-Drain RESET
2.32
MAX803Z
Open-Drain RESET
Open-Drain RESET
4.63
MAX809L
Push-Pull RESET
OUTPUT TYPE
RESET THRESHOLD (V)
PART/SUFFIX
--
--
--
ADAA
ACAA
CWAA
ABAA
--
--
--
AAAA
TOP MARK
ABB
ABA
AAZ
AAQ
AAP
--
AAO
ABC
ABD
ABE
AAN
AHAA
AGAA
--
AFAA
AAU
AAT
AAS
AAR
4.38
MAX810M
4.63
MAX810L
2.32
MAX809Z
2.63
MAX809R
Push-Pull RESET
Push-Pull RESET
Push-Pull RESET
Push-Pull RESET
AKAA
AJAA
AAX
AAV
2.93
MAX810S
3.08
MAX810T
Push-Pull RESET
Push-Pull RESET
MAX810R
2.63
Push-Pull RESET
ALAA
AAW
MAX810Z
2.32
Push-Pull RESET
--
AAY
SOT
SC70
Selector Guide
0
POWER-DOWN RESET DELAY vs.
TEMPERATURE (MAX8_ _J/L/M)
80
100
120
140
MAX803-TOC4
TEMPERATURE (C)
POWER-DOWN RESET DELAY (
s)
40
20
60
-40
85
20
-20
0
60
40
V
OD
= V
TH
- V
CC
V
OD
= 10mV
V
OD
= 100mV
V
OD
= 200mV
V
OD
= 20mV
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
_______________________________________________________________________________________
5
Detailed Description
A microprocessor's (P's) reset input starts the P 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.
Applications Information
Negative-Going V
CC
Transients
In addition to issuing a reset to the P 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 20s or less
will not cause a reset pulse. A 0.1F bypass capacitor
mounted as close as possible to the V
CC
pin provides
additional transient immunity.
Ensuring a Valid Reset Output
Down to V
CC
= 0
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 P 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
3-Pin Microprocessor Reset Circuits
R1
100k
V
CC
GND
MAX809
RESET
Figure 2. RESET Valid to V
CC
= Ground Circuit
2
RESET
(MAX803/
MAX809)
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.
1
GND
Ground
PIN
NAME
FUNCTION
RESET
(MAX810)
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.
_____________________Pin Description
400
320
0
1
100
1000
160
80
240
RESET COMPARATOR OVERDRIVE, V
TH
- V
CC
(mV)
MAXIMUM TRANSIENT DURATION (
s)
10
T
A
= +25C
MAX8_ _J/L/M
MAX8_ _R/S/T/Z
Figure 1. Maximum Transient Duration Without Causing a
Reset Pulse vs. Reset Comparator Overdrive
3
V
CC
Supply Voltage (+5V, +3.3V, +3.0V, or
+2.5V)
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