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19-1294; Rev 4; 12/05
3-Pin, Ultra-Low-Power SC70/SOT
µP Reset Circuits
General Description
The MAX6326/MAX6327/MAX6328/MAX6346/MAX6347/
MAX6348 microprocessor (µP) supervisory circuits moni-
tor the power supplies in µP and digital systems. These
devices provide excellent circuit reliability and low cost
by eliminating external components and adjustments
when used with 2.5V, 3V, 3.3V, and 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
100ms after V
CC
has risen above the reset threshold.
The only difference between the devices is their output.
The MAX6326/MAX6346 (push-pull) and MAX6328/
MAX6348 (open-drain) have an active-low reset output.
The MAX6327/MAX6347 have an active-high push-pull
reset output. All of these parts are guaranteed to be in
the correct state for V
CC
down to 1V. The reset compara-
tor is designed to ignore fast transients on V
CC
. Reset
thresholds are factory-trimmable between 2.2V and
4.63V, in approximately 100mV increments. Twenty-one
standard versions are available. Contact the factory for
availability of nonstandard versions.
Ultra-low supply currents (1µA max for the MAX6326/
MAX6327/MAX6328) make these parts ideal for use in
portable equipment. All six devices are available in
space-saving SOT23 and SC70 packages.
♦
Ultra-Low 1µA (max) Supply Current
(MAX6326/MAX6327/MAX6328)
♦
Precision Monitoring of 2.5V, 3V, 3.3V, and 5V
Power-Supply Voltages
♦
Reset Thresholds Available from 2.2V to 4.63V
♦
Fully Specified Over Temperature
♦
100ms (min) Power-On Reset Pulse Width
♦
Low Cost
♦
Available in Three Versions: Push-Pull
RESET,
Push-Pull RESET, and Open-Drain
RESET
♦
Power-Supply Transient Immunity
♦
No External Components
♦
3-Pin SC70/SOT23 Packages
♦
Pin Compatible with MAX803/MAX809/MAX810
Features
MAX6326/MAX6327/MAX6328/MAX6346/MAX6347/MAX6348
Ordering Information
PART
†
MAX6326XR_
_-T
MAX6326UR_ _-T
MAX6327XR_
_-T
MAX6327UR_ _-T
MAX6328XR_
_-T
MAX6328UR_ _-T
MAX6346XR_
_-T
MAX6346UR_ _-T
MAX6347XR_
_-T
MAX6347UR_ _-T
MAX6348XR_
_-T
MAX6348UR_ _-T
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
3 SC70-3
3 SOT23-3
3 SC70-3
3 SOT23-3
3 SC70-3
3 SOT23-3
3 SC70-3
3 SOT23-3
3 SC70-3
3 SOT23-3
3 SC70-3
3 SOT23-3
Applications
Computers
Controllers
Critical µP and µC
Power Monitoring
Intelligent Instruments
Automotive
Portable/Battery-Powered
Equipment
Pin Configuration
TOP VIEW
GND
1
MAX6326
MAX6327
MAX6328
MAX6346
MAX6347
MAX6348
(RESET) RESET
2
3
V
CC
†The
MAX6326/MAX6327/MAX6328/MAX6346/MAX6347/
MAX6348 are available in factory-set V
CC
reset thresholds from
2.2V to 4.63V, in approximately 0.1V increments. Choose the
desired reset-threshold suffix from Table 1 and insert it in the
blank spaces following “R.” There are 21 standard versions with
a required order increment of 2500 pieces. Sample stock is gen-
erally held on the standard versions only (see the Selector
Guide). Required order increment is 10,000 pieces for nonstan-
dard versions (Table 2). Contact factory for availability. All
devices available in tape-and-reel only.
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
SOT23-3/SC70-3
( ) ARE FOR THE MAX6327/MAX6347.
Selector Guide appears 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.
3-Pin, Ultra-Low-Power SC70/SOT
µP Reset Circuits
MAX6326/MAX6327/MAX6328/MAX6346/MAX6347/MAX6348
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND)
V
CC
...........................................................................-0.3V to +6V
RESET,
RESET
(push-pull) .........................-0.3V to (V
CC
+ 0.3V)
RESET
(open drain)..................................................-0.3V to +6V
Input Current (V
CC
) .............................................................20mA
Output Current (RESET,
RESET).........................................20mA
Rate of Rise (V
CC
) ...........................................................100V/µs
Continuous Power Dissipation (T
A
= +70°C)
3-Pin SC70 (derate 2.7mW/°C above +70°C) ...............174mW
3-Pin SOT23 (derate 4mW/°C above +70°C)................320mW
Operating Temperature Range ...........................-40°C to +85°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
= full range, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C and V
CC
= 3V.) (Note 1)
PARAMETER
V
CC
Range
SYMBOL
CONDITIONS
T
A
= 0°C to +70°C
T
A
= -40°C to +85°C
I
CC
MAX632_ only, V
CC
= 3.0V for V
TH
≤
2.93V,
V
CC
= 3.2V for V
TH
> 2.93V, no load
V
CC
= 5.5V, no load
T
A
= +25°C
Reset Threshold
V
TH
Table 1
T
A
= -40°C to +85°C
Reset Threshold Tempco
V
CC
to Reset Delay
Reset Active Timeout Period
RESET
Output Voltage
(MAX6326/MAX6328/
MAX6346/MAX6348)
RESET
Output Voltage
(MAX6326/MAX6346)
I
SINK
= 1.6mA, V
CC
> 2.1V, reset asserted
V
OL
I
SINK
= 100µA, V
CC
≥
1.2V, reset asserted
I
SOURCE
= 500µA, V
CC
= 3.2V, MAX6326 only
V
OH
I
SOURCE
= 800µA, V
CC
= 4.5V, V
TH
≤
4.38V
I
SOURCE
= 800µA, V
CC
= V
TH(MAX)
, V
TH
≥
4.5V
V
OH
RESET Output Voltage
(MAX6327/MAX6347)
V
OL
I
SOURCE
= 500µA, V
CC
≥
2.1V, reset asserted
I
SOURCE
= 50µA, V
CC
≥
1.2V, reset asserted
I
SINK
= 1.2mA, V
CC
≥
3.2V, reset not asserted,
MAX6327 only
I
SINK
= 3.2mA, V
CC
≥
4.5V, reset not asserted,
V
TH
≤
4.38V
I
SINK
= 3.2mA, V
CC
= V
TH(MAX)
, V
TH
≥
4.5V
RESET Threshold
Hysteresis
Open-Drain
RESET
Output
Leakage Current
Note 1:
Overtemperature limits are guaranteed by design and not production tested.
MAX6326/MAX6327/MAX6328
MAX6346/MAX6347/MAX6348
6.3
9.5
0.1
0.8
·
V
CC
0.8
·
V
CC
0.8
·
V
CC
0.8
·
V
CC
0.8
·
V
CC
0.3
0.4
0.4
mV
µA
V
V
∆V
TH
/°C
V
CC
= V
TH
to (V
TH
- 100mV)
100
V
TH
-
1.5%
V
TH
-
2.5%
MIN
1.0
1.2
0.5
1.0
V
TH
V
TH
40
20
185
280
0.3
V
0.4
TYP
MAX
5.5
5.5
1.0
1.75
V
TH
+
1.5%
V
TH
+
2.5%
UNITS
V
Supply Current
µA
V
ppm/°C
µs
ms
2
_______________________________________________________________________________________
3-Pin, Ultra-Low-Power SC70/SOT
µP Reset Circuits
__________________________________________Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
0.9
0.8
SUPPLY CURRENT (µA)
RESET DELAY (µs)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
V
CC
= 1.2V
0
-40
-20
0
50
V
OD
= 100mV
V
OD
= 200mV
20
40
60
80
TEMPERATURE (°C)
V
CC
= 3.3V
V
CC
= 5V
150
MAX6326-01
MAX6326/MAX6327/MAX6328/MAX6346/MAX6347/MAX6348
POWER-DOWN RESET DELAY
vs. TEMPERATURE
200
MAX6326-02
1.0
100
V
OD
= 20mV
V
OD
= 10mV
POWER-UP RESET TIMEOUT
vs. TEMPERATURE
MAX6326-03
MAXIMUM TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE (SC70)
MAXIMUM TRANSIENT DURATION (µs)
MAX6326-04
210
POWER-UP RESET TIMEOUT (ms)
200
190
180
170
160
150
140
130
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
500
400
300
200
100
0
1
10
100
1000
RESET THRESHOLD OVERDRIVE,
V
TH
- V
CC
(mV)
______________________________________________________________Pin Description
PIN
PIN
MAX6327
MAX6347
1
NAME
GND
Ground
Active-Low Reset Output.
RESET
remains low while V
CC
is below the reset
threshold and for at least 100ms after V
CC
rises above the reset threshold.
RESET
is open-drain on the MAX6328/MAX6348 and push-pull on the
MAX6326/MAX6346.
Active-High Reset Output. RESET remains high while V
CC
is below the reset
threshold and for at least 100ms after V
CC
rises above the reset threshold.
Supply Voltage
FUNCTION
MAX6326/MAX6346
MAX6328/MAX6348
1
2
—
RESET
—
3
2
3
RESET
V
CC
_______________________________________________________________________________________
3
3-Pin, Ultra-Low-Power SC70/SOT
µP Reset Circuits
MAX6326/MAX6327/MAX6328/MAX6346/MAX6347/MAX6348
____________ Applications Information
Interfacing to µPs with
Bidirectional Reset Pins
Since the
RESET
output on the MAX6328/MAX6348 is
open drain, these devices interface easily with micro-
processors (µPs) that have bidirectional reset pins,
such as the Motorola 68HC11. Connecting the µP
supervisor’s
RESET
output directly to the microcon-
troller’s (µC’s)
RESET
pin with a single pull-up resistor
allows either device to assert reset (Figure 1).
V
CC
V
CC
V
CC
MAX6328
MAX6348
µP
RESET
RESET
INPUT
MOTOROLA
68HCXX
Negative-Going V
CC
Transients
In addition to issuing a reset to the µP during power-up,
power-down, and brownout conditions, these devices
are relatively immune to short-duration, negative-going
V
CC
transients (glitches).
The
Typical Operating Characteristics
show the Maxi-
mum Transient Duration vs. Reset Threshold Overdrive
graph, for which reset pulses are not generated. The
graph shows the maximum pulse width that a negative-
going V
CC
transient may typically have when issuing a
reset signal. As the amplitude of the transient increas-
es, the maximum allowable pulse width decreases.
GND
GND
Figure 1. Interfacing to µPs with Bidirectional Reset Pins
Table 1. Factory-Trimmed Reset Thresholds
‡
RESET THRESHOLD VOLTAGE, V
TH
(V)
PART
MAX632_ _R
MAX632_ _R
MAX632_ _R
MAX632_ _R
MAX632_ _R
MAX632_ _R
MAX632_ _R
MAX632_ _R
MAX632_ _R
MAX632_ _R
MAX634_ _R
MAX634_ _R
MAX634_ _R
MAX634_ _R
MAX634_ _R
MAX634_ _R
SUFFIX
MIN
22
23
24
25
26
27
28
29
30
31
33
34
35
36
37
38
2.167
2.285
2.364
2.462
2.591
2.660
2.758
2.886
2.955
3.034
3.250
3.349
3.447
3.546
3.644
3.743
T
A
= +25°C
TYP
2.200
2.320
2.400
2.500
2.630
2.700
2.800
2.930
3.000
3.080
3.300
3.400
3.500
3.600
3.700
3.800
MAX
2.233
2.355
2.436
2.537
2.669
2.741
2.842
2.974
3.045
3.126
3.350
3.451
3.552
3.654
3.755
3.857
T
A
= -40°C to +85°C
MIN
2.145
2.262
2.340
2.437
2.564
2.633
2.730
2.857
2.925
3.003
3.217
3.315
3.412
3.510
3.607
3.705
MAX
2.250
2.375
2.460
2.562
2.696
2.768
2.870
3.000
3.075
3.150
3.383
3.485
3.587
3.690
3.792
3.895
‡
Factory-trimmed reset thresholds are available in approximately 100mV increments with a 1.5% room-temperature variance.
4
_______________________________________________________________________________________
Microcontroller MCU
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