19-2336; Rev 1; 8/03
Low-Power, Single/Dual-Voltage µP Reset Circuits
with Capacitor-Adjustable Reset Timeout Delay
General Description
The MAX6412–MAX6420 low-power microprocessor
supervisor circuits monitor system voltages from 1.6V to
5V. These devices are designed to assert a reset signal
whenever the V
CC
supply voltage or RESET IN falls below
its reset threshold or the manual reset input is asserted.
The reset output remains asserted for the reset timeout
period after V
CC
and RESET IN rise above the reset
threshold and the manual reset input is deasserted. The
reset timeout is externally set by a capacitor to provide
more flexibility.
The MAX6412/MAX6413/MAX6414 feature fixed thresholds
from 1.575V to 5V in approximately 100mV increments and
a manual reset input. The MAX6415/MAX6416/MAX6417
are offered with an adjustable reset input that can monitor
voltages down to 1.26V and the MAX6418/MAX6419/
MAX6420 are offered with one fixed input and one
adjustable input to monitor dual-voltage systems.
The MAX6412/MAX6415/MAX6418 have an active-low,
push-pull reset output. The MAX6413/MAX6416/
MAX6419 have an active-high, push-pull reset output
and the MAX6414/MAX6417/MAX6420 have an active-
low, open-drain reset output. All of these devices are
offered in a SOT23-5 package and are fully specified
from -40°C to +125°C.
Features
o
Monitor System Voltages from 1.6V to 5V
o
Capacitor-Adjustable Reset Timeout Period
o
Manual Reset Input (MAX6412/MAX6413/MAX6414)
o
Adjustable Reset Input Option
(MAX6415–MAX6420)
o
Dual-Voltage Monitoring
(MAX6418/MAX6419/MAX6420)
o
Low Quiescent Current (1.7µA, typ)
o
3 RESET Output Options
Push-Pull
RESET
Push-Pull RESET
Open-Drain
RESET
o
Guaranteed Reset Valid to V
CC
= 1V
o
Power-Supply Transient Immunity
o
Small SOT23-5 Packages
MAX6412–MAX6420
Ordering Information
PART
MAX6412UK_
_-T
MAX6413UK_
_-T
MAX6414UK_
_-T
MAX6415UK-T
MAX6416UK-T
MAX6417UK-T
MAX6418UK_
_-T
MAX6419UK_
_-T
MAX6420UK_
_-T
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
Applications
Automotive
Medical Equipment
Intelligent Instruments
Portable Equipment
Battery-Powered Computers/Controllers
Embedded Controllers
Critical µP Monitoring
Set-Top Boxes
Computers
Pin Configuration
TOP VIEW
RESET/RESET
1
5
V
CC
GND
2
MAX6412–
MAX6420
4
SRT
Note:
The MAX6412/MAX6413/MAX6414 and MAX6418/
MAX6419/MAX6420 are available with factory-set V
CC
reset
thresholds from 1.575V to 5.0V in approximately 0.1V incre-
ments. Insert the desired nominal reset threshold suffix (from
Table 1) into the blanks following the letters UK. There are 33
standard versions with a required order increment of 2500
pieces. Sample stock is generally held on standard versions
only (see Standard Versions Table). Required order increment is
10,000 pieces for nonstandard versions. Contact factory for
availability. All devices are available in tape-and-reel only.
Typical Operating Circuit appears at end of data sheet.
Selector Guide appears at end of data sheet.
RESET IN (MR)
3
SOT23-5
( ) FOR THE MAX6412/MAX6413/MAX6414.
________________________________________________________________
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.
Low-Power, Single/Dual-Voltage µP Reset Circuits
with Capacitor-Adjustable Reset Timeout Delay
MAX6412–MAX6420
ABSOLUTE MAXIMUM RATINGS
All Voltages Referenced to GND
V
CC
........................................................................-0.3V to +6.0V
SRT,
MR,
RESET IN ....................................-0.3V to (V
CC
+ 0.3V)
RESET,
RESET
(Push-Pull) .........................-0.3V to (V
CC
+ 0.3V)
RESET
(Open-Drain) .............................................-0.3V to +6.0V
Input Current (All Pins) .....................................................±20mA
Output Current (RESET, RESET) ......................................±20mA
Continuous Power Dissipation (T
A
= +70°C)
5-Pin SOT23-5 (derate 7.1mW/°C above +70°C) ........571mW
Operating Temperature Range .........................-40°C to +125°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
= 1V to 5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise specified. Typical values are at V
CC
= 5V and T
A
= +25°C.) (Note 1)
PARAMETER
Supply Voltage Range
Supply Current
SYMBOL
V
CC
V
CC
≤
5.0V
I
CC
V
CC
≤
3.3V
V
CC
≤
2.0V
T
A
= +25°C
V
CC
Reset Threshold Accuracy
V
TH
T
A
= 0°C to +125°C
T
A
= -40°C to 0°C
Hysteresis
V
CC
to Reset Delay
Reset Timeout Period
V
SRT
Ramp Current
V
SRT
Ramp Threshold
RAMP Threshold Hysteresis
RESET
Output Voltage LOW
V
OL
V
HYST
t
RD
t
RP
I
RAMP
V
TH-RAMP
V
CC
falling at 1mV/µs
C
SRT
= 1500pF
C
SRT
= 0
V
SRT
= 0 to 0.65V; V
CC
= 1.6V to 5V
V
CC
= 1.6V to 5V (V
RAMP
rising)
V
RAMP
falling threshold
V
CC
≥
1.0V, I
SINK
= 50µA
V
CC
≥
2.7V, I
SINK
= 1.2mA
V
CC
≥
4.5V, I
SINK
= 3.2mA
RESET
Output Voltage HIGH,
(Push-Pull)
RESET
Output Leakage Current,
(Open-Drain)
V
CC
≥
1.8V, I
SOURCE
= 200µA
V
OH
V
CC
≥
2.25V, I
SOURCE
= 500µA
V
CC
≥
4.5V, I
SOURCE
= 800µA
I
LKG
V
CC
> V
TH
, reset not asserted
V
CC
≥
1.0V, I
SOURCE
= 1µA
RESET Output Voltage HIGH
V
OH
V
CC
≥
1.8V, I
SOURCE
= 150µA
V
CC
≥
2.7V, I
SOURCE
= 500µA
V
CC
≥
4.5V, I
SOURCE
= 800µA
0.8
✕
V
CC
0.8
✕
V
CC
0.8
✕
V
CC
0.8
✕
V
CC
V
0.8
✕
V
CC
0.8
✕
V
CC
0.8
✕
V
CC
1.0
µA
V
3.35
V
TH
-
1.5%
V
TH
-
2.5%
V
TH
-
3.5%
3
✕
V
TH
100
4.375
0.275
240
0.65
33
0.3
0.3
0.4
V
5.40
CONDITIONS
MIN
1.0
2.7
2
1.7
TYP
MAX
5.5
4.5
3.5
2.5
V
TH
+
1.5%
V
TH
+
2.5%
V
TH
+
3.5%
µA
UNITS
V
V
mV
µs
ms
nA
V
mV
2
_______________________________________________________________________________________
Low-Power, Single/Dual-Voltage µP Reset Circuits
with Capacitor-Adjustable Reset Timeout Delay
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 1V to 5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise specified. Typical values are at V
CC
= 5V and T
A
= +25°C.) (Note 1)
PARAMETER
RESET Output Voltage LOW
RESET IN Leakage Current
RESET IN Threshold
RESET IN Hysteresis
V
IL
MR
Input
V
IH
V
IL
V
IH
MR
Minimum Pulse Width
MR
Glitch Rejection
MR
to RESET Delay
MR
Pullup Resistance
Pull up to V
CC
12
V
CC
> 4.0V
V
CC
< 4.0V
2.4
0.3
✕
V
CC
0.7
✕
V
CC
1
75
50
20
28
µs
ns
µs
kΩ
V
RST
V
RST
falling, V
CC
= 1.6V to 5.0V
1.212
1.263
25
0.8
V
SYMBOL
V
OL
CONDITIONS
V
CC
≥
1.8V, I
SINK
= 500µA
V
CC
≥
2.7V, I
SINK
= 1.2mA
V
CC
≥
4.5V, I
SINK
= 3.2mA
MIN
TYP
MAX
0.3
0.3
0.4
10
1.313
nA
V
mV
V
UNITS
MAX6412–MAX6420
Note 1:
Devices production tested at +25°C. Over temperature limits are guaranteed by design.
Typical Operating Characteristics
(V
CC
= 5V, C
SRT
= 1500pF, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs.
SUPPLY VOLTAGE
MAX6412-20 toc01
SUPPLY CURRENT vs.
TEMPERATURE
MAX6412-20 toc02
RESET TIMEOUT PERIOD vs. C
SRT
MAX6412-20 toc03
4
T
A
= +125°C
SUPPLY CURRENT (µA)
3
T
A
= +25°C
2
T
A
= -40°C
1
3.5
3.0
SUPPLY CURRENT (µA)
2.5
V
CC
= 3.3V
2.0
V
CC
= 1.8V
1.5
1.0
V
CC
= 1V
0.5
V
CC
= 5V
10,000
RESET TIMEOUT PERIOD (ms)
1000
100
10
1
0
0
1
2
3
4
5
6
SUPPLY VOLTAGE (V)
0
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
0.1
0.001
0.01
0.1
1
C
SRT
(nF)
10
100
1000
_______________________________________________________________________________________
3
Low-Power, Single/Dual-Voltage µP Reset Circuits
with Capacitor-Adjustable Reset Timeout Delay
MAX6412–MAX6420
Typical Operating Characteristics (continued)
(V
CC
= 5V, C
SRT
= 1500pF, T
A
= +25°C, unless otherwise noted.)
RESET TIMEOUT PERIOD
vs. TEMPERATURE
C
SRT
= 1500pF
MAX6412-20 toc04
RESET TIMEOUT PERIOD
vs. TEMPERATURE
C
SRT
= 0
550
RESET TIMEOUT PERIOD (µs)
500
450
400
350
300
250
MAX6412-20 toc05
4.30
600
RESET TIMEOUT PERIOD (ms)
4.25
4.20
4.15
4.10
4.05
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
200
-50
-25
0
75
50
TEMPERATURE (°C)
25
100
125
RESET IN THRESHOLD VOLTAGE
vs. TEMPERATURE
MAX6412-20 toc06
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
MAX6412-20 toc07
1.280
RESET IN THRESHOLD VOLTAGE (V)
1.275
1.270
1.265
1.260
1.255
1.250
-50
-25
0
25
50
75
100
175
150
TRANSIENT DURATION (µs)
125
100
75
50
25
V
TH
= 3.0V
0
RESET OCCURS
ABOVE THE CURVE
125
0
200
400
600
800
1000
TEMPERATURE (°C)
RESET THRESHOLD OVERDRIVE (mV)
4
_______________________________________________________________________________________
Low-Power, Single/Dual-Voltage µP Reset Circuits
with Capacitor-Adjustable Reset Timeout Delay
Pin Description
PIN
MAX6412/
MAX6413/
MAX6414
MAX6415/
MAX6416/
MAX6417
MAX6418/
MAX6419/
MAX6420
NAME
FUNCTION
MAX6412–MAX6420
RESET
1
1
1
RESET
RESET
changes from high to low whenever V
CC
or RESET IN drops below
the selected reset threshold voltage (V
TH
or V
RESET IN
, respectively) or
manual reset is pulled low.
RESET
remains low for the reset timeout period
after all reset conditions are deasserted and then goes high.
RESET changes from low to high whenever the V
CC
or RESET IN drops
below the selected reset threshold voltage (V
TH
or V
RESET IN
) or manual
reset is pulled low. RESET remains high for the reset timeout period after all
reset conditions are deasserted and then goes low.
Ground
Reset Input. High-impedance input to the adjustable reset comparator.
Connect RESET IN to the center point of an external resistor-divider
network to set the threshold of the externally monitored voltage. See
Reset
Threshold
section.
Manual Reset Input. Pull this pin low to manually reset the device. Reset
remains asserted for the reset timeout period after
MR
is released.
Set Reset Timeout Input. Connect a capacitor between SRT and ground to
set the timeout period. Determine the period as follows:
t
RP
= (2.73 x 10
6
)
✕
C
SRT
+ 275µs with t
RP
in seconds and C
SRT
in Farads.
Supply Voltage and Input for Fixed-Threshold V
CC
Monitor
2
2
2
GND
RESET
IN
—
3
3
3
—
—
MR
4
5
4
5
4
5
SRT
V
CC
Detailed Description
The MAX6412–MAX6420 low-power microprocessor
(µP) supervisory circuits provide maximum adjustability
for supply-voltage monitoring and reset functionality. In
addition, the MAX6412–MAX6420 reset timeout period
is adjustable using an external capacitor.
The MAX6412/MAX6413/MAX6414 have factory-
trimmed reset threshold voltages in approximately
100mV increments from 1.575V to 5.0V with a manual
reset input. The MAX6415/MAX6416/MAX6417 contain
a reset threshold that can be adjusted to any voltage
above 1.26V using external resistors. The MAX6418/
MAX6419/MAX6420 offer both a factory-trimmed reset
threshold and an adjustable reset threshold input for
dual-voltage monitoring.
A reset signal is asserted when V
CC
and/or RESET IN
falls below the preset values or when
MR
is asserted.
The reset remains asserted for an externally pro-
grammed interval after V
CC
and/or RESET IN has risen
above the reset threshold or
MR
is deasserted.
in a known state. The MAX6412–MAX6420 µP supervi-
sory circuits provide the reset logic to prevent code-
execution errors during power-up, power-down, and
brownout conditions (see
Typical Operating Circuit).
For the MAX6413, MAX6416, and MAX6419, RESET
changes from low to high whenever V
CC
or RESET IN
drops below the reset threshold voltages. Once RESET
IN and V
CC
exceed their respective reset threshold volt-
age(s), RESET remains high for the reset timeout period,
then goes low.
On power-up, once V
CC
reaches 1V, RESET is guaran-
teed to be a logic high. For applications requiring valid
reset logic when V
CC
is less than 1V, see the section
Ensuring a Valid RESET/
RESET
Output Down to V
CC
= 0.
The active-low
RESET
output of the remaining supervi-
sors is the inverse of the MAX6413, MAX6416, and
MAX6419 active-high RESET output and is guaranteed
valid for V
CC
≥
1V.
Reset Threshold
The MAX6415–MAX6420 monitor the voltage on RESET
IN with an external resistor voltage-divider (Figure 1).
Reset Output
The reset output is typically connected to the reset
input of a µP. A µP’s reset input starts or restarts the µP
_______________________________________________________________________________________
5
