Maxim MAX809MEXR-T 3-pin microprocessor reset circuit Datasheet

19-0344; Rev 4; 12/99
3-Pin Microprocessor Reset 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 pull-up
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
____________________________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
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
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
-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
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
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.
Pin Configuration
Typical Operating Circuit
TOP VIEW
VCC
GND 1
VCC
VCC
RPULL-UP*
RESET
MAX803
MAX809
MAX810
µP
MAX803
MAX809
RESET
INPUT
3
VCC
RESET (RESET) 2
GND
GND
SC70-3/SOT23-3
*MAX803 ONLY
( ) ARE FOR MAX810.
MAX803 AVAILABLE IN SC70-3 ONLY.
________________________________________________________________ Maxim Integrated Products
1
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For small orders, phone 1-800-835-8769.
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
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.
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
3-Pin Microprocessor Reset Circuits
ABSOLUTE MAXIMUM RATINGS
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 .........................-40°C to +105°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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
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, 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
VCC Range
Supply Current (SOT23)
Supply Current (SC70)
ICC
ICC
CONDITIONS
TA = -40°C to +105°C
1.2
5.5
TA = -40°C to
+85°C
VCC < 5.5V, MAX8_ _J/L/M
24
60
VCC < 3.6V, MAX8_ _R/S/T
17
50
TA = +85°C to
+105°C
VCC < 5.5V, MAX8_ _L/M
100
VCC < 3.6V, MAX8_ _R/S/T
100
TA = -40°C to
+85°C
VCC < 5.5V, MAX8_ _L/M
16
35
VCC < 3.6V, MAX8_ _R/S/T/Z
12
30
TA = +85°C to
+105°C
VCC < 5.5V, MAX8_ _L/M
MAX809J
(SOT only)
MAX8_ _T
MAX8_ _S
MAX8_ _R
MAX8_ _Z
(SC70 only)
2
MAX
5.5
MAX8_ _M
VTH
TYP
1.0
MAX8_ _L
Reset Threshold
MIN
TA = 0°C to +70°C
UNITS
V
µA
75
VCC < 3.6V, MAX8_ _R/S/T/Z
75
TA = +25°C
4.56
4.63
4.70
TA = -40°C to +85°C
4.50
TA = +85°C to +105°C
4.40
TA = +25°C
4.31
TA = -40°C to +85°C
4.25
TA = +85°C to +105°C
4.16
TA = +25°C
3.93
TA = -40°C to +85°C
3.89
TA = +85°C to +105°C
3.80
TA = +25°C
3.04
TA = -40°C to +85°C
3.00
3.15
TA = +85°C to +105°C
2.92
3.23
TA = +25°C
2.89
TA = -40°C to +85°C
2.85
TA = +85°C to +105°C
2.78
TA = +25°C
2.59
TA = -40°C to +85°C
2.55
TA = +85°C to +105°C
2.50
TA = +25°C
2.28
TA = -40°C to +85°C
2.25
2.38
TA = +85°C to +105°C
2.21
2.45
4.75
4.86
4.38
4.45
4.50
4.56
4.00
4.06
4.10
4.20
3.08
2.93
3.11
2.96
3.00
3.08
2.63
2.66
2.70
2.76
2.32
_______________________________________________________________________________________
2.35
V
3-Pin Microprocessor Reset Circuits
(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.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
Reset Threshold Tempco
MAX
30
VCC to Reset Delay (Note 2)
VCC = VTH to (VTH - 100mV)
Reset Active Timeout Period
(SOT23)
TA = -40°C to +85°C
140
TA = +85°C to +105°C
100
Reset Active Timeout Period
(SC70)
TA = -40°C to +85°C
140
TA = +85°C to +105°C
100
RESET Output Voltage Low
(push-pull active low and opendrain active-low, MAX803 and
MAX809)
VOL
RESET Output Voltage High
(push-pull active low, MAX809)
VOH
RESET Output Voltage Low
(push-pull active high, MAX810)
VOL
RESET Output Voltage High
(push-pull active high, MAX810)
VOH
RESET Open-Drain Output
Leakage Current (MAX803)
20
µs
240
560
840
240
460
840
VCC = VTH min, ISINK = 1.2mA,
MAX803R/S/T/Z, MAX809R/S/T/Z
0.3
VCC = VTH min, ISINK = 3.2mA,
MAX803L/M, MAX809J/L/M
0.4
VCC > 1.0V, ISINK = 50µA
0.3
VCC > VTH max, ISOURCE = 500µA,
MAX809R/S/T/Z
0.8VCC
VCC > VTH max, ISOURCE = 800µA,
MAX809J/L/M
VCC - 1.5
UNITS
ppm/°C
ms
ms
V
V
VCC = VTH max, ISINK = 1.2mA,
MAX810R/S/T/Z
0.3
VCC = VTH max, ISINK = 3.2mA,
MAX810L/M
0.4
V
1.8V < VCC < VTH min, ISOURCE = 150µA
0.8VCC
V
VCC > VTH, RESET deasserted
1
µA
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.
Typical Operating Characteristics
(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.)
SUPPLY CURRENT vs. TEMPERATURE
(SC70 PACKAGE, NO LOAD)
SUPPLY CURRENT (µA)
MAX8_ _L/M, VCC = 5V
MAX8_ _R/S/T, VCC = 3.3V
10
MAX8_ _Z, VCC = 2.5V
5
VOD = VTH - VCC
80
MAX803-TOC3
100
POWER-DOWN RESET DELAY (µs)
MAX803 toc01
15
POWER-DOWN RESET DELAY vs.
TEMPERATURE (MAX8_ _R/S/T/Z)
VOD = 10mV
60
VOD = 20mV
40
VOD = 100mV
20
MAX8_ _L/M/R/S/T/Z, VCC = 1V
VOD = 200mV
0
0
-40
-20
0
20
40
TEMPERATURE (°C)
60
85
-40
-20
20
0
40
TEMPERATURE (°C)
60
85
_______________________________________________________________________________________
40
3
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics (continued)
(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.)
POWER-UP RESET TIMEOUT
vs. TEMPERATURE
100
VOD = 20mV
80
60
40
VOD = 100mV
20
VOD = 200mV
0
-40
-20
20
0
40
TEMPERATURE (°C)
60
1.002
245
MAX8_ _J/L/M
240
MAX8_ _R/S/T/Z
235
230
1.001
1.000
0.999
0.998
225
85
1.003
MAX803-TOC6
VOD = 10mV
250
MAX803-TOC5
120
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE
NORMALIZED THRESHOLD
VOD = VTH - VCC
POWER-UP RESET TIMEOUT (ms)
140
MAX803-TOC4
POWER-DOWN RESET DELAY vs.
TEMPERATURE (MAX8_ _J/L/M)
POWER-DOWN RESET DELAY (µs)
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
3-Pin Microprocessor Reset Circuits
0.997
-40
-20
0
20
40
60
85
-40
TEMPERATURE (°C)
-20
0
20
40
60
85
TEMPERATURE (°C)
Selector Guide
4
TOP MARK
PART/SUFFIX
RESET THRESHOLD (V)
OUTPUT TYPE
MAX803L
4.63
Open-Drain RESET
—
AAZ
MAX803M
4.38
Open-Drain RESET
—
ABA
MAX803T
3.08
Open-Drain RESET
—
ABB
MAX803S
2.93
Open-Drain RESET
—
ABC
MAX803R
2.63
Open-Drain RESET
—
ABD
MAX803Z
2.32
Open-Drain RESET
—
ABE
MAX809L
4.63
Push-Pull RESET
AAAA
AAN
MAX809M
4.38
Push-Pull RESET
ABAA
AAO
SOT
SC70
MAX809J
4.00
Push-Pull RESET
CWAA
—
MAX809T
3.08
Push-Pull RESET
ACAA
AAP
MAX809S
2.93
Push-Pull RESET
ADAA
AAQ
MAX809R
2.63
Push-Pull RESET
AFAA
AAR
MAX809Z
2.32
Push-Pull RESET
—
AAS
MAX810L
4.63
Push-Pull RESET
AGAA
AAT
MAX810M
4.38
Push-Pull RESET
AHAA
AAU
AAV
MAX810T
3.08
Push-Pull RESET
AJAA
MAX810S
2.93
Push-Pull RESET
AKAA
AAX
MAX810R
2.63
Push-Pull RESET
ALAA
AAW
MAX810Z
2.32
Push-Pull RESET
—
AAY
_______________________________________________________________________________________
3-Pin Microprocessor Reset Circuits
PIN
NAME
1
GND
FUNCTION
VCC
Ground
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.
VCC
Supply Voltage (+5V, +3.3V, +3.0V, or
+2.5V)
2
3
MAX809
RESET
GND
R1
100k
Figure 2. RESET Valid to VCC = Ground Circuit
Applications Information
MAXIMUM TRANSIENT DURATION (µs)
400
Negative-Going VCC Transients
TA = +25°C
320
240
160
MAX8_ _J/L/M
80
MAX8_ _R/S/T/Z
0
1
10
100
1000
RESET COMPARATOR OVERDRIVE, VTH - VCC (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 powerup, 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 pull-up resistor on the MAX803’s RESET output to any supply between 0 and 6V.
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 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 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 = 0
When VCC falls below 1V, the MAX809 RESET output
no longer sinks current—it becomes an open circuit.
Therefore, high-impedance CMOS logic inputs connected 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
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
_____________________Pin Description
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
3-Pin Microprocessor Reset Circuits
+5.0V
+3.3V
VCC
VCC
VCC
RPULLUP
µP
MAX803
RESET
GND
VCC
VCC
MOTOROLA
RESET 68HCXX
INPUT
GND
Figure 3. Interfacing to µPs with Bidirectional Reset I/O
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 pull-up 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 supervisor’s RESET output directly
to the microcontroller’s (µC’s) RESET pin with a single
pull-up resistor allows either device to assert reset
(Figure 3).
5V SYSTEM
MAX803
RESET
RESET
INPUT
GND
GND
Figure 4. MAX803 Open-Drain RESET Output Allows Use with
Multiple Supplies
Benefits 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.
MAX803 Open-Drain RESET Output
Allows Use with Multiple Supplies
Generally, the pull-up 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 pull-up, RESET will be pulled
high as VCC decays toward 0. The voltage where this
occurs depends on the pull-up resistor value and the
voltage to which it is connected.
6
___________________Chip Information
TRANSISTOR COUNT: 275 (SOT23)
380 (SC70)
_______________________________________________________________________________________
3-Pin Microprocessor Reset Circuits
SC70, 3L.EPS
_______________________________________________________________________________________
7
MAX803L/M/R/S/T/Z, MAX809J/L/M/R/S/T/Z, MAX810L/M/R/S/T/Z
Package Information
Package Information (continued)
SOTPO3L.EPS
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 cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1999 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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