19-2656; Rev 1; 1/03
µP Reset Circuits with Long Manual Reset
Setup Period
General Description
The MAX6443–MAX6452 low-current microprocessor
reset circuits feature single or dual manual reset inputs
with an extended 6.72s setup period. Because of the
extended setup period, short switch closures (nuisance
resets) are ignored.
On all devices, the reset output asserts when any of the
monitored supply voltages drops below its specified
threshold. The reset output remains asserted for the
reset timeout period (210ms typ) after all monitored
supplies exceed their reset thresholds. The reset output
is one-shot pulse asserted for the reset timeout period
(140ms min) when selected manual reset input(s) are
held low for an extended setup timeout period of 6.72s.
These devices ignore manual reset transitions of less
than 6.72s (typ).
The MAX6443–MAX6448 are single fixed-voltage µP
supervisors. The MAX6443/MAX6444 have a single
extended manual reset input. The MAX6445/MAX6446
have two extended manual reset inputs. The MAX6447/
MAX6448 have one extended and one immediate manual
reset input.
The MAX6449–MAX6452 have one fixed-threshold µP
supervisor and one adjustable-threshold µP supervisor.
The MAX6449/MAX6450 have two delayed manual
reset inputs. The MAX6451/MAX6452 have one delayed
and one immediate manual reset input.
The MAX6443–MAX6452 have an active-low
RESET
with push-pull or open-drain output logic options. These
devices, offered in small SOT packages, are fully guar-
anteed over the extended temperature range (-40°C to
+85°C).
Features
o
Single- or Dual-Supply Voltage Monitors
o
Precision Factory-Set Reset Thresholds from
1.6V to 4.6V
o
Adjustable Threshold to Monitor Voltages Down
to 0.63V (MAX6449–MAX6452)
o
Single or Dual Manual Reset Inputs with Extended
6.72s Setup Period
o
Optional Short Setup Time Manual Reset Input
(MAX6447/MAX6448 and MAX6451/MAX6452)
o
Immune to Short Voltage Transients
o
Low 6µA Supply Current
o
Guaranteed Valid Reset Down to V
CC
= 1.0V
o
Active-Low
RESET
(Push-Pull or Open-Drain)
Outputs
o
140ms (min) Reset Timeout Period
o
Small SOT143 and SOT23 Packages
MAX6443–MAX6452
Ordering Information
PART
MAX6443
US_ _L -T
MAX6444
US_ _L -T
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
4 SOT143-4
4 SOT143-4
Applications
Set-Top Boxes
Consumer Electronics
DVD Players
Modems
MP3 Players
Industrial Equipment
Automotive
Medical Devices
Note:
The “_ _ ” is a placeholder for the threshold voltage level
of the devices. A desired threshold level is set by the two-num-
ber suffix found in Table 1. All devices are available in tape-
and-reel only. There is a 2500-piece minimum order increment
for standard versions (Table 2). Sample stock is typically held
on standard versions only. Nonstandard versions require a
minimum order increment of 10,000 pieces. Contact factory for
availability.
Pin Configurations
TOP VIEW
GND
1
4
V
CC
MAX6443
MAX6444
RESET
2
3
MR1
SOT143
Pin Configurations continued at end of data sheet.
________________________________________________________________
Maxim Integrated Products
1
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.
µP Reset Circuits with Long Manual Reset
Setup Period
MAX6443–MAX6452
ABSOLUTE MAXIMUM RATINGS
All Voltages Referenced to GND
V
CC
..........................................................................-0.3V to +6V
Open-Drain
RESET
..................................................-0.3V to +6V
Push-Pull
RESET
........................................-0.3V to (V
CC
+ 0.3V)
MR1,
MR2,
MR2,
RSTIN ..........................................-0.3V to +6V
Input Current, All Pins.......................................................±20mA
Continuous Power Dissipation (T
A
= +70°C)
4-Pin SOT143-4 (derate 4.0mW/°C above +70°C) .....320mW
5-Pin SOT23-5 (derate 7.1mW/°C above +70°C) .......571mW
6-Pin SOT23-6 (derate 8.7mW/°C above +70°C) .......696mW
Operating Temperature Range .......................... -40°C to +85°C
Junction Temperature ......................................................+150°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
= 1.0V to 5.5V, T
A
= -40°C to +85°C, unless otherwise specified. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Operating Voltage Range
V
CC
Supply Current
SYMBOL
V
CC
I
CC
V
CC
= 5.5V, no load
V
CC
= 3.6V, no load
46
44
31
29
V
CC
Reset Threshold
V
TH
26
23
22
17
16
Reset Threshold Tempco
Reset Threshold Hysteresis
RSTIN Threshold
RSTIN Threshold Hysteresis
RSTIN Input Current
RSTIN to Reset Output Delay
Reset Timeout Period
V
CC
to
RESET
Output Delay
MR1
Minimum Setup Period
Pulse Width
MR1 + MR2
Minimum Setup
Period Pulse Width
t
RP
t
RD
t
MR
MAX6445/MAX6446/MAX6449/MAX6450
V
CC
falling at 1mV/µs
4.48
4.48
V
TH-RSTIN
V
HYST
I
RSTIN
MAX6449–MAX6452
MAX6449–MAX6452
MAX6449–MAX6452
MAX6449–MAX6452, V
RSTIN
falling at
1mV/µs
140
-25
15
210
20
6.72
6.72
8.96
8.96
280
T
A
= 0°C to +85°C
T
A
= -40°C to +85°C
0.615
0.610
2.5
+25
4.50
4.25
3.00
2.85
2.55
2.25
2.12
1.62
1.52
CONDITIONS
MIN
1.0
7
6
4.63
4.38
3.08
2.93
2.63
2.32
2.19
1.67
1.58
60
2
×
V
TH
0.630
0.645
0.650
TYP
MAX
5.5
20
16
4.75
4.50
3.15
3.00
2.70
2.38
2.25
1.71
1.62
ppm/°C
mV
V
mV
nA
µs
ms
µs
s
s
V
UNITS
V
µA
2
_______________________________________________________________________________________
µP Reset Circuits with Long Manual Reset
Setup Period
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 1.0V to 5.5V, T
A
= -40°C to +85°C, unless otherwise specified. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
MR2 Minimum Setup Period
Pulse Width
MR2 Glitch Rejection
MR2 to
RESET
Delay
Manual Reset Timeout Period
MR1
to V
CC
Pullup Impedance
MR2
to V
CC
Pullup Impedance
MAX6445/MAX6446/MAX6449/MAX6450
V
CC
≥
1.00V, I
SINK
= 50µA,
RESET
asserted
V
CC
≥
1.20V, I
SINK
= 100µA,
RESET
asserted
V
OL
V
CC
≥
2.55V, I
SINK
= 1.2mA,
RESET
asserted
V
CC
≥
4.25V, I
SINK
= 3.2mA,
RESET
asserted
V
CC
≥
1.80V, I
SOURCE
= 200µA,
RESET
deasserted
RESET
Output High
(Push-Pull)
V
OH
V
CC
≥
3.15V, I
SOURCE
= 500µA,
RESET
deasserted
V
CC
≥
4.75V, I
SOURCE
= 800µA,
RESET
deasserted
RESET
Open-Drain Leakage
Current
MR1, MR2,
MR2
Input Low Voltage
MR1, MR2,
MR2
Input High Voltage
I
LKG
V
IL
V
IH
0.7
×
V
CC
RESET
deasserted
0.8
×
V
CC
0.8
×
V
CC
0.8
×
V
CC
1
0.3
×
V
CC
µA
V
V
V
t
MRP
SYMBOL
CONDITIONS
MAX6447/MAX6448/MAX6451/MAX6452
MAX6447/MAX6448/MAX6451/MAX6452
MAX6447/MAX6448/MAX6451/MAX6452
140
25
25
MIN
1
100
200
210
50
50
280
75
75
0.3
0.3
V
0.3
0.4
TYP
MAX
UNITS
µs
ns
ns
ms
kΩ
kΩ
MAX6443–MAX6452
RESET
Output Low
(Open Drain or Push-Pull)
Note 1:
Devices production tested at +25°C. Overtemperature limits are guaranteed by design.
_______________________________________________________________________________________
3
µP Reset Circuits with Long Manual Reset
Setup Period
MAX6443–MAX6452
Typical Operating Characteristics
(V
CC
= 3.3V, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6443/52 toc01
NORMALIZED RESET TIMEOUT PERIOD
vs. TEMPERATURE
MAX6443/52 toc02
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
MAX6443/52 toc03
9
8
SUPPLY CURRENT (µA)
7
6
5
4
3
2
1
0
T
A
= -40°C
T
A
= +25°C
T
A
= +85°C
1.05
1.04
NORMALIZED TIMEOUT PERIOD
1.03
1.02
1.01
1.00
0.99
0.98
0.97
0.96
0.95
250
TRANSIENT DURATION (µs)
200
150
RESET OCCURS
ABOVE THE CURVE
100
50
V
TH
= 4.4V
0
-40
-15
10
35
60
85
0
200
400
600
800
1000
TEMPERATURE (°C)
RESET THRESHOLD OVERDRIVE (mV)
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY VOLTAGE (V)
NORMALIZED V
CC
RESET THRESHOLD
vs. TEMPERATURE
MAX6443/52 toc04
V
CC
TO RESET DELAY
vs. TEMPERATURE
MAX6443/52 toc05
RSTIN TO RESET DELAY
vs. TEMPERATURE (RSTIN FALLING)
23.6
RSTIN TO RESET DELAY (µs)
23.2
22.8
22.4
22.0
21.6
21.2
20.8
20.4
20.0
RSTIN FALLING AT 1mV/µs
MAX6443/52 toc06
1.03
NORMALIZED V
CC
RESET THRESHOLD
1.02
1.01
1.00
0.99
0.98
0.97
-40
-15
10
35
60
24.0
23.6
V
CC
TO RESET DELAY (µs)
23.2
22.8
22.4
22.0
21.6
21.2
20.8
20.4
20.0
V
CC
= FALLING AT 1mV/µs
24.0
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
MANUAL RESET TO RESET DELAY
(MAX6445/MAX6446/MAX6449/MAX6450)
MAX6443/52 toc07
V
CC
TO RESET DELAY
MAX6443/52 toc08
V
CC
= 5V
MR1
(5V/div)
V
CC
= 4.5V
V
TH
= 4.392V
V
CC
(100mV/div)
V
CC
= 4.3V
MR2
(5V/div)
RESET
(5V/div)
TIME (1s/div)
TIME (100µs/div)
RESET
(2V/div)
4
_______________________________________________________________________________________
µP Reset Circuits with Long Manual Reset
Setup Period
Pin Description
PIN
MAX6443
MAX6444
1
MAX6445
MAX6446
2
MAX6447
MAX6448
2
MAX6449
MAX6450
2
MAX6451
MAX6452
2
NAME
GND
Ground
Active-Low Push-Pull or Open-Drain Output.
RESET
changes from high to low when V
CC
or RSTIN drops below
its selected reset threshold and remains low for the 210ms
reset timeout period after all monitored power-supply inputs
exceed their selected reset thresholds.
RESET
is one-shot
pulsed low for the reset timeout period (140ms min) after
selected manual reset inputs are asserted longer than the
specified setup period. For the open-drain output, use a
minimum 20kΩ pullup resistor to V
CC
.
Manual Reset Input, Active Low. Internal 50kΩ pullup to
V
CC.
Pull
MR1
low for the typical input pulse width
(6.72s) to one-shot pulse
RESET
for the reset timeout
period.
Manual Reset Input, Active Low. Pull both
MR1
and
MR2
low for the typical input pulse width (6.72s) to one-
shot pulse
RESET
for the reset timeout period.
V
CC
V
CC
Voltage Input. Power supply and input for the
primary microprocessor voltage reset monitor.
Manual Reset Input, Active Low. Internal 50kΩ pullup to
V
CC
. Pull both
MR1
and
MR2
low for the typical input
pulse width (6.72s) to one-shot pulse
RESET
for the
reset timeout period.
Manual Reset Input. Pull the MR2 high to immediately
one-shot pulse
RESET
for the reset timeout period.
Reset Input. High-impedance input to the adjustable
reset comparator. Connect RSTIN to the center point of
an external resistor-divider to set the threshold of the
externally monitored voltage.
FUNCTION
MAX6443–MAX6452
2
1
1
1
1
RESET
3
—
3
—
3
MR1
—
3
—
3
—
4
4
4
4
4
—
5
—
6
—
MR2
—
—
5
—
6
MR2
—
—
—
5
5
RSTIN
Detailed Description
Reset Output
The reset output is typically connected to the reset
input of a microprocessor (µP). A µP’s reset input starts
or restarts the µP in a known state. The MAX6443–
MAX6452 µP supervisory circuits provide the reset
logic to prevent code-execution errors during power-
up, power-down and brownout conditions (see the
Typical Operating Circuit).
RESET
changes from high to low whenever the moni-
tored voltages (RSTIN or V
CC
) drop below the reset
threshold voltages. Once V
RSTIN
and V
CC
exceed their
respective reset threshold voltages,
RESET
remains low
for the reset timeout period and then goes high.
RESET
is one-shot pulsed whenever selected manual reset
inputs are asserted.
RESET
stays asserted for the nor-
mal reset timeout period (140ms min).
RESET
is guaranteed to be in the proper output logic
state for V
CC
inputs
≥
1V. For applications requiring valid
reset logic when V
CC
is less than 1V, see the
Ensuring a
Valid
RESET
Output Down to V
CC
= 0V
section.
_______________________________________________________________________________________
5
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