19-2523; Rev 1; 11/05
Microprocessor Supervisory Reset Circuits
with Edge-Triggered, One-Shot Manual Reset
Features
The MAX6467/MAX6468 microprocessor (µP) supervisory circuits monitor single power-supply voltages from
+1.8V to +5.0V and assert a reset if the supply voltage
drops below its preset threshold. An edge-triggered,
one-shot manual reset function ensures that the µP
enters the reset mode for a fixed timeout period only,
even in the event of a continuously asserted manual
reset. The MAX6467/MAX6468 significantly improve
system reliability compared to traditional manual reset
supervisory circuits.
A variety of factory-trimmed threshold options accommodate different supply voltages and tolerances, eliminating
external components. The factory-set thresholds range
from +1.575V to +4.625V to monitor +5.0V, +3.3V, +3.0V,
+2.5V, and +1.8V supplies with various tolerances. Reset
timeout periods of 150ms (min) and 1200ms (min) are
available to accommodate different µP platforms.
A single, active-low RESET output asserts when VCC
drops below its threshold or if the edge-triggered MR
asserts low. RESET remains low for the reset timeout
period after VCC rises above its threshold and for a fixed,
one-shot timeout period after a manual reset input falling
edge. RESET remains valid as long as VCC remains
above +1V. Open-drain (MAX6467) and push-pull
(MAX6468) output options provide additional flexibility in
the system design.
♦ Precision Factory-Set Reset Threshold Voltages
for +5.0V, +3.3V, +3.0V, +2.5V, and +1.8V Supplies
The MAX6467/MAX6468 are offered in the space-saving
4-pin SOT143 package and the ultra-small 4-pin SC70
package and are specified over the automotive (-40°C to
+125°C) temperature range.
Applications
Cell Phones/PDAs
Embedded Control Systems
Industrial Equipment
Automotive Products
♦ Edge-Triggered Manual Reset Input with OneShot Pulsed Reset Output
♦ Two Reset Timeout Period Options (150ms or
1200ms min)
♦ Immune to Short Voltage Transients
♦ Low Supply Current (3µA at VCC = +1.8V)
♦ RESET Valid to VCC = +1V
♦ Active-Low Open-Drain and Push-Pull RESET
Output Options
♦ -40°C to +125°C Operating Temperature Range
♦ Small 4-Pin SC70 and SOT143 Packages
♦ No External Components Required
♦ Pin Compatible with MAX811, MAX6315,
MAX6384, and MAX6386
Ordering Information
PART
MAX6467XS_ _D_-T
MAX6467US_ _D_-T
MAX6468XS_ _D_-T
MAX6468US_ _D_-T
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
Note: Insert reset threshold suffix (see Reset Threshold table)
after XS or US. Insert reset timeout delay (see Reset Timeout
Delay table) after D to complete the part number. Sample stock
is generally held on standard versions only (see Standard
Versions table). Standard versions have an order increment
requirement of 2500 pieces. Nonstandard versions have an
order increment requirement of 10,000 pieces. Contact factory
for availability.
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “T” with “+T” when ordering.
Portable/Battery-Powered Equipment
Pin Configurations
Medical Devices
DSL Modems
MP3 Players
TOP VIEW
GND 1
GPS Systems
Digital Cameras
PIN-PACKAGE
4 SC70-4
4 SOT143-4
4 SC70-4
4 SOT143-4
RESET 2
MAX6467XS
MAX6468XS
4
VCC
3
MR
SC70
Typical Operating Circuit appears at end of data sheet.
Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX6467/MAX6468
General Description
MAX6467/MAX6468
Microprocessor Supervisory Reset Circuits
with Edge-Triggered, One-Shot Manual Reset
ABSOLUTE MAXIMUM RATINGS
Continuous Power Dissipation (TA = +70°C)
4-Pin SC70 (derate 3.1mW/°C above +70°C) ..............245mW
4-Pin SOT143 (derate 4mW/°C above +70°C).............320mW
Operating Temperature Range .........................-40°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature ......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
VCC to GND ...........................................................-0.3V to +6.0V
RESET to GND
Open-Drain........................................................-0.3V to +6.0V
Push-Pull.................................................-0.3V to (VCC + 0.3V)
MR to GND .................................................-0.3V to (VCC + 0.3V)
Input/Output Current (all pins) ............................................20mA
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 = +1.2V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
Operating Voltage Range
Supply Current
VCC Reset Threshold
(See the Reset Threshold Table)
SYMBOL
VCC
ICC
VTH
CONDITIONS
tRD
VCC Reset Timeout Period
tRP
TYP
MAX
TA = 0°C to +125°C
1.0
5.5
TA = -40°C to 0°C
1.2
5.5
VCC = +5.5V, no load
7
13
VCC = +3.6V, no load
6
11
VCC = +2.5V, no load
4
8
VCC = +1.8V, no load
3
7.5
TA = +25°C
-1.5%
TA = -40°C to +85°C
-2.5%
+2.5%
-3%
+3%
TA = +85°C to +125°C
VCC Reset Delay
MIN
VCC falling at 10mV/µs from VTH + 100mV
to VTH - 100mV
VTH
UNITS
V
µA
+1.5%
35
V
µs
D3 option
150
225
300
D7 option
1200
1800
2400
ms
MR Timeout Period
tMRP
D3 and D7 options
150
225
300
ms
MR Rising Debounce Period
(Note 2)
tDEB
D3 and D7 options
150
225
300
ms
VIL
MR Input Voltage
VIH
VIL
VIH
VTH < +4V
VTH ≥ +4V
MR Minimum Input Pulse
0.3 x VCC
0.7 x VCC
0.8
V
2.4
1
µs
MR Glitch Rejection
100
ns
MR to RESET Delay
200
ns
MR Pullup Resistance
RESET Output High
(MAX6468 Only)
2
MR to VCC
VOH
750
VCC ≥ +2.5V, ISOURCE = 500µA, RESET not
asserted
0.8 x VCC
VCC ≥ +4.5V, ISOURCE = 800µA, RESET not
asserted
0.8 x VCC
1500
2250
Ω
V
_______________________________________________________________________________________
Microprocessor Supervisory Reset Circuits
with Edge-Triggered, One-Shot Manual Reset
(VCC = +1.2V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
RESET Output Low
VOL
RESET Output Leakage Current
(MAX6467 Only)
CONDITIONS
MIN
TYP
MAX
VCC ≥ +1V, ISINK = 80µA, RESET asserted
0.3
VCC ≥ +2.5V, ISINK = 1.2mA, RESET
asserted
0.3
VCC ≥ +4.5V, ISINK = 3.2mA, RESET
asserted
0.3
RESET not asserted
ILKG
UNITS
V
1
µA
Note 1: Specifications over temperature are guaranteed by design. Production testing at TA = +25°C only.
Note 2: The MR input ignores falling edges that occur within the MR rising debounce period (tDEB) after MR first rises from low to
high (after a valid MR reset assertion). This prevents invalid reset assertion due to switch bounce.
Typical Operating Characteristics
(VCC = +5V, MAX6468US29D3 device, TA = +25°C, unless otherwise noted.)
6
5
4
3
VCC = +2.5V
6
5
4
3
2
VCC = +1.8V
1
MAX6467 toc03
VCC = VTH + 100mV TO VTH - 100mV
24
22
20
18
1
0
0
16
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
RESET TIMEOUT PERIOD
vs. TEMPERATURE
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE
OUTPUT VOLTAGE LOW
vs. SINK CURRENT
208
207
206
205
204
203
202
1.010
NORMALIZED RESET THRESHOLD (V)
MAX6467 toc04
209
1.005
450
1.000
400
350
300
250
200
0.995
VCC = 5.0V
150
100
50
0
201
200
600
550
500
MAX6467 toc06
-40 -25 -10 5 20 35 50 65 80 95 110 125
210
RESET TIMEOUT PERIOD (ms)
7
VOL (mV)
2
8
VCC TO RESET DELAY (µs)
7
26
MAX6467 toc02
VCC = +3.6V
9
MAX6467 toc05
SUPPLY CURRENT (µA)
8
VCC = +5.5V
SUPPLY CURRENT (µA)
9
10
MAX6467 toc01
10
VCC TO RESET DELAY
vs. TEMPERATURE
SUPPLY CURRENT vs. SUPPLY VOLTAGE
SUPPLY CURRENT vs. TEMPERATURE
0.990
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
TEMPERATURE (°C)
0
1
2
3
4
5
6
7
8
9
10
ISINK (mA)
_______________________________________________________________________________________
3
MAX6467/MAX6468
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics (continued)
(VCC = +5V, MAX6468US29D3 device, TA = +25°C, unless otherwise noted.)
4.5
4.0
VOH (V)
3.5
3.0
2.5
2.0
1.5
1.0
600
MAX6467 toc08
VCC = +5.0V
5.0
MAXIMUM TRANSIENT DURATION (µs)
5.5
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
MAX6467 toc07
OUTPUT VOLTAGE HIGH
vs. SOURCE CURRENT
500
400
300
200
RESET ASSERTS
ABOVE THIS LINE
100
0.5
0
0
0
1
2
3
4
5
6
7
8
0
10
20
30
40
50
ISOURCE (mA)
RESET THRESHOLD OVERDRIVE (mV)
MR TO RESET DELAY
vs. TEMPERATURE
PROPAGATION DELAY
(WITH 100mV OVERDRIVE)
60
MAX6467 toc10
MAX6467 toc09
120
115
MR TO RESET DELAY (ns)
MAX6467/MAX6468
Microprocessor Supervisory Reset Circuits
with Edge-Triggered, One-Shot Manual Reset
110
105
3.0V
VCC 100mV/div
AC-COUPLED
100
95
2.8V
90
85
3V
80
75
RESET 1V/div
70
65
60
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
4µs/div
TEMPERATURE (°C)
RESET PULLUP AND PULLDOWN RESPONSE
RESET TIMEOUT PERIOD
MAX6467 toc12
MAX6467 toc11
CRESET = 47pF, RPULLUP = 100kΩ,
VPULLUP = 1.6V
3.3V
VCC 2V/div
1.675V
VCC 200mV/div
1.475V
0
1.6V
3.3V
RESET 500mV/div
RESET 2V/div
0
0
MAX6467_S16D3-T
40µs/div
4
40ms/div
_______________________________________________________________________________________
Microprocessor Supervisory Reset Circuits
with Edge-Triggered, One-Shot Manual Reset
PIN
NAME
1
GND
FUNCTION
Ground
Reset Output. RESET is an active-low open-drain (MAX6467) or push-pull (MAX6468) output. RESET asserts
low when VCC drops below the selected threshold and remains low for the VCC reset timeout period after
VCC rises above the threshold. The RESET one-shot asserts low for a fixed MR reset timeout period on the
falling edge of the manual reset input. The open-drain output requires an external pullup resistor.
2
RESET
3
MR
Manual Reset Input. Drive MR low to initiate a reset output. MR controls an edge-triggered one-shot that
asserts RESET low for a fixed MR timeout period when MR is driven low. Internal timing circuitry ignores
switch close and open bounce to ensure proper one-shot reset timing.
4
VCC
Power-Supply Input. VCC provides power to the device and is also a monitored voltage. When VCC drops
below the selected threshold, RESET asserts low and remains low for the reset timeout period after VCC rises
above the threshold. For better noise immunity, bypass VCC to GND with a 0.1µF capacitor.
VCC
VTH
GND
SWITCH
BOUNCE
MR
SWITCH
BOUNCE
SWITCH
BOUNCE
GND
RESET
tRP
tMRP
tDEB
tMRP
GND
Figure 1. Timing Diagram
Detailed Description
Reset Output
The MAX6467 provides an active-low open-drain
RESET output. The MAX6468 provides an active-low
push-pull RESET output. RESET asserts low if V CC
drops below the selected threshold or if a falling edge
occurs on MR. RESET remains low for the VCC reset
timeout period after VCC increases above the threshold
voltage or is one-shot pulsed low for the MR timeout
period after a falling edge on MR.
Manual Reset Input
Many µP-based products require manual reset capability,
allowing the operator, a test technician, or external logic
circuitry to initiate a reset. A falling edge on MR asserts
RESET low. RESET is one-shot pulsed low for the MR
timeout period after a falling edge on MR. An internal
1.5kΩ pullup resistor to VCC allows MR to be left unconnected if not used. MR can be driven with TTL or CMOSlogic levels, or with open-drain/collector outputs. Connect
a normally open momentary pushbutton switch from MR
to GND to realize a manual reset function. External
debounce circuitry is not required, as the MAX6467/
MAX6468 respond to the first falling edge on MR and
ignore subsequent falling edges within the reset timeout
period and during the MR debounce period (see Figure
1). After MR goes high for 150ms (tDEB), the manual reset
one-shot is ready to trigger a reset on the next MR falling
edge. Connect a 0.1µF capacitor from MR to GND when
using long cables to provide additional noise immunity
(Figure 2).
_______________________________________________________________________________________
5
MAX6467/MAX6468
Pin Description
MAX6467/MAX6468
Microprocessor Supervisory Reset Circuits
with Edge-Triggered, One-Shot Manual Reset
Reset Timeout Delay*
RESET TIMEOUT SUFFIX
VCC RESET TIMEOUT PERIOD
(min/max) (ms)
MR TIMEOUT PERIOD
(min/max) (ms)
MR RISING DEBOUNCE PERIOD
(min/max) (ms)
D3
150/300
150/300
150/300
D7
1200/2400
150/300
150/300
*Additional reset timeout options may be available. Contact factory for availability.
Applications Information
Falling VCC Transients
In addition to issuing a reset to the µP during power-up,
power-down, and brownout conditions, the MAX6467/
MAX6468 are relatively immune to short-duration falling
V CC transients (glitches). The Typical Operating
Characteristics section shows the Maximum Transient
Duration vs. V CC Overdrive for which the MAX6467/
MAX6468 do not generate a reset pulse. This graph was
generated using a falling pulse applied to VCC starting
above the actual reset threshold and ending below the
threshold by the magnitude indicated (VCC Overdrive).
The graph indicates the typical maximum pulse width a
falling VCC transient can have without initiating a reset
pulse. As the magnitude of the transient increases (goes
farther below the reset threshold), the maximum allowable
pulse width decreases. A 0.1µF bypass capacitor from
VCC to GND provides additional transient immunity.
Ensuring a Valid RESET Output Down
to VCC = 0V
The MAX6467/MAX6468 guarantee proper operation
down to VCC = +1V. In applications that require valid
reset levels down to VCC = 0V, a pulldown resistor to
active-low outputs (MAX6468 only, Figure 3) ensures
that RESET remains valid while the RESET output can
no longer sink current. This scheme does not work with
the open-drain outputs of the MAX6467. Ensure that the
resistor value used does not overload the RESET output
when VCC is above the reset threshold. For most applications, use 100kΩ to 1MΩ.
VCC
VCC
MAX6467
MAX6468
1.5kΩ
MR
VCC
MR ONE-SHOT/
DEBOUNCE
RESET
TIMEOUT
PERIOD
RESET
MAX6468
R1
100kΩ
RESET
OUTPUT
RESET
GND
VCC
1.23V
Figure 3. RESET Valid to VCC = 0V
GND
Chip Information
Figure 2. Functional Diagram
TRANSISTOR COUNT: 748
PROCESS: BiCMOS
6
_______________________________________________________________________________________
Microprocessor Supervisory Reset Circuits
with Edge-Triggered, One-Shot Manual Reset
PART
TOP MARK
MAX6467XS16D3
AGL
MAX6467XS22D3
MAX6467XS26D3
MAX6467XS29D3
Reset Threshold (-40°C to +85°C)
SUFFIX
VTH (min)
VTH (typ)
VTH (max)
AGM
46
4.509
4.625
4.741
AGN
45
4.388
4.500
4.613
AGO
44
4.266
4.375
4.484
MAX6467XS46D3
AGP
43
4.193
4.300
4.408
MAX6467US16D3
KAFN
42
4.095
4.200
4.305
MAX6467US22D3
KAFO
41
3.998
4.100
4.203
MAX6467US26D3
KAFP
40
3.900
4.000
4.100
MAX6467US29D3
KAFQ
39
3.803
3.900
3.998
MAX6467US46D3
KAFR
38
3.705
3.800
3.895
MAX6468XS16D3
AGQ
37
3.608
3.700
3.793
MAX6468XS22D3
AGR
36
3.510
3.600
3.690
MAX6468XS26D3
AGS
35
3.413
3.500
3.588
MAX6468XS29D3
AGC
34
3.315
3.400
3.485
MAX6468XS46D3
AGB
33
3.218
3.300
3.383
MAX6468US16D3
KAFS
32
3.120
3.200
3.280
MAX6468US22D3
KAFT
31
2.998
3.075
3.152
MAX6468US26D3
KAFU
30
2.925
3.000
3.075
MAX6468US29D3
KAEW
29
2.852
2.925
2.998
MAX6468US46D3
KAFV
28
2.730
2.800
2.870
27
2.633
2.700
2.768
26
2.559
2.625
2.691
25
2.438
2.500
2.563
24
2.340
2.400
2.460
23
2.255
2.313
2.370
22
2.133
2.188
2.242
21
2.048
2.100
2.153
20
1.950
2.000
2.050
19
1.853
1.900
1.948
18
1.755
1.800
1.845
17
1.623
1.665
1.707
16
1.536
1.575
1.614
Typical Operating Circuit
+1.0V TO +5.5V
VCC
VCC
MAX6467
MAX6468
MR
RESET
RESET
INPUT
µP
Pin Configurations (continued)
GND
GND
TOP VIEW
GND 1
RESET 2
MAX6467US
MAX6468US
4
VCC
3
MR
SOT143
_______________________________________________________________________________________
7
MAX6467/MAX6468
Standard Versions
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
SOT-143 4L.EPS
MAX6467/MAX6468
Microprocessor Supervisory Reset Circuits
with Edge-Triggered, One-Shot Manual Reset
PACKAGE OUTLINE, SOT-143, 4L
21-0052
8
_______________________________________________________________________________________
E
1
1
Microprocessor Supervisory Reset Circuits
with Edge-Triggered, One-Shot Manual Reset
SC70, 4L.EPS
PACKAGE OUTLINE, 4L SC70
21-0098
C
1
1
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9
© 2005 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.
MAX6467/MAX6468
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
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