General Description
The MAX6803/MAX6804/MAX6805 microprocessor (µP)
supervisory circuits monitor the power supplies in 2.85V
to 5.0V µP and digital systems. They increase circuit
reliability and reduce cost by eliminating external com-
ponents and adjustments. They also feature a
debounced manual reset input.
These devices perform a single function: they assert a
reset signal whenever the V
CC
supply voltage declines
below a preset threshold or whenever manual reset is
asserted. Reset remains asserted for a preset timeout
period after V
CC
has risen above the reset threshold or
after manual reset is deasserted. The only difference
among the three devices is their output. The MAX6804
(push/pull) and MAX6805 (open-drain) have an active-
low RESET output, while the MAX6803 (push/pull) has
an active-high RESET output. The MAX6803/MAX6804
are guaranteed to be in the correct state for V
CC
down
to 0.7V. The MAX6805 is guaranteed to be in the cor-
rect state for V
CC
down to 1.0V.
The reset comparator in these ICs is designed to ignore
fast transients on V
CC
. Reset thresholds are factory-
trimmable between 2.63V and 4.80V, in approximately
100mV increments. These devices are available with a
1ms min, 20ms min, or 100ms min reset timeout period.
Ideal for space-critical applications, the MAX6803/
MAX6804/MAX6805 come packaged in a 4-pin
SOT143. For a lower threshold voltage version, see the
MAX6335/MAX6336/MAX6337.
Applications
Computers
Controllers
Intelligent Instruments
Critical µP/µC Power Monitoring
Portable/Battery-Powered Equipment
Automotive
Features
o Ultra-Low 0.7V Operating Supply Voltage
o Low 4.0µA Supply Current
o Precision Monitoring of 2.85V to 5.0V Power-
Supply Voltages
o Reset Thresholds Available from 2.63V to 4.80V,
in Approximately 100mV Increments
o Debounced Manual Reset Input
o Fully Specified over Temperature
o Three Power-On Reset Timeout Periods Available
(1ms min, 20ms min, 100ms min)
o Low Cost
o Three Available Output Structures: Push/Pull
RESET, Push/Pull RESET, Open-Drain RESET
o Guaranteed RESET/RESET Valid to V
CC
= 0.7V
(MAX6803/MAX6804)
o Power-Supply Transient Immunity
o No External Components Required
o 4-Pin SOT143 Package
o Pin Compatible with MAX811/MAX812 and
MAX6314/MAX6315
MAX6803/MAX6804/MAX6805
4-Pin, Low-Power
µP Reset Circuits with Manual Reset
________________________________________________________________ Maxim Integrated Products
1
19-1946; Rev 1; 2/01
PART*
MAX6803US_ _D_-T
MAX6804US_ _D_-T
MAX6805US_ _D_-T
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
TEMP. RANGE
PIN-PACKAGE
4 SOT143
4 SOT143
4 SOT143
Ordering Information
*These devices are available in factory-set V
CC
reset thresh-
olds from 2.63V to 4.80V, in approximately 0.1V increments.
Choose the desired reset threshold suffix from Table 1 and
insert it in the blanks following "US" in the part number.
Factory-programmed reset timeout periods are also available.
Insert the number corresponding to the desired nominal reset
timeout period (1 = 1ms min, 2 = 20ms min, 3 = 100ms min) in
the blank following "D" in the part number. There are 15 stan-
dard versions with a required order increment of 2500 pieces.
Sample stock is generally held on the standard versions only
(see Selector Guide). Contact the factory for availability of non-
standard versions (required order increment is 10,000 pieces).
All devices available in tape-and-reel only.
Typical Operating Circuit and Pin Configuration appear
at end of data sheet.
Selector Guide appears at end of data sheet.
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.
MAX6803/MAX6804/MAX6805
4-Pin, Low-Power
µP Reset Circuits with Manual Reset
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(
V
CC
= full range, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at
V
CC
= +5.0V and T
A
= +25°C, reset not
asserted.) (Note 1)
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.
Terminal Voltage (with respect to GND)
V
CC
......................................................................-0.3V to +6V
Push/Pull RESET or RESET, MR ............-0.3V to (V
CC
+ 0.3V)
Open-Drain RESET ..............................................-0.3V to +6V
Input Current (V
CC
) .............................................................20mA
Output Current (RESET, RESET).........................................20mA
Continuous Power Dissipation (T
A
= +70°C)
4-Pin SOT143 (derate 4mW/°C above +70°C) ............320mW
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
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX6803/MAX6804
0.7
5.5
T
A
= 0°C to +125°C
MAX6805
1.0
5.5
MAX6803/MAX6804
0.78
5.5
Supply Voltage Range
(Note 1)
V
CC
T
A
= -40°C to +125°C
MAX6805
1.2
5.5
V
V
CC
= +3.0V
4
10
Supply Current
I
CC
No load
V
CC
= +5.0V
5
12
µA
T
A
= +25°C
V
TH
- 1.8%
V
TH
V
TH
+ 1.8%
Reset Threshold
V
TH
MAX680_US_ _D_-T,
Table 1
T
A
= - 40°C to + 125°C
V
TH
- 3%
V
TH
V
TH
+ 3%
V
V
CC
Falling Reset Delay
V
CC
falling at 10V/ms
30
µs
MAX680_US_ _D1-T
1
1.5
2
MAX680_US_ _D2-T
20
30
40
Reset Active Timeout Period
t
RP
MAX680_US_ _D3-T
100
150
200
ms
MR Minimum Pulse Width
1
µs
MR Glitch Immunity
50
ns
MR Reset Delay
0.1
µs
V
IL
0.3
V
CC
MR Input Voltage
V
IH
0.7
V
CC
V
MR Pullup Resistance
12
20
30
k
I
SINK
= 50µA, V
CC
1.0V
0.4
I
SINK
= 1.2mA, V
CC
2.5V
0.3
RESET Output Low Voltage
(MAX6804/MAX6805)
V
OL
Reset
asserted
I
SINK
= 3.2mA, V
CC
4.25V
0.4
V
I
SOURC E
= 500µA, V
CC
3.0V
0.8
V
CC
RESET Output High Voltage
(MAX6804)
V
OH
Reset not
asserted
I
SOURC E
= 800µA, V
CC
5.0V
0.8
V
CC
V
4-Pin, Low-Power
µP Reset Circuits with Manual Reset
_______________________________________________________________________________________
3
3.0
4.0
3.5
5.0
4.5
6.0
5.5
6.5
-50
0
25
-25
50
75
100
125
SUPPLY CURRENT vs. TEMPERATURE
MAX6803/04/05 toc01
TEMPERATURE (
°C)
I
CC
(
µ
A)
V
CC
= +5.0V
V
CC
= +3.3V
0.950
0.980
0.970
0.960
1.000
0.990
1.040
1.030
1.020
1.010
1.050
-50
-25
0
25
50
75
100
125
NORMALIZED RESET TIMEOUT PERIOD
vs. TEMPERATURE
MAX6803/04/05 toc02
TEMPERATURE (
°C)
NORMALIZED RESET TIMEOUT PERIOD
80
60
40
20
0
1.0
1.5
2.5
3.0
OUTPUT VOLTAGE LOW
vs. SUPPLY VOLTAGE
MAX6803/04/05 toc03
V
CC
(V)
OUTPUT VOLTAGE LOW (mV)
+25
°C
-40
°C
+125
°C
+85
°C
V
TH
= 2.93V
I
SINK
= 500
µA
RESET
2.0
100
75
50
25
0
1.0
2.0
1.5
2.5
OUTPUT VOLTAGE HIGH
vs. SUPPLY VOLTAGE
MAX6803/04/05 toc04
V
CC
(V)
OUTPUT VOLTAGE HIGH (V
CC
- V
OH
) (mV)
+25
°C
-40
°C
+125
°C
+85
°C
V
TH
= 2.93V
I
SINK
= 100
µA
RESET ASSERTED
(MAX6803)
3.0
100
1000
0
100
200
400
300
500
600
0.1
1
10
MAXIMUM TRANSIENT DURATION
vs. RESET COMPARATOR OVERDRIVE
MAX6803/04/05 toc05
RESET COMPARATOR OVERDRIVE (mV)
MAXIMUM TRANSIENT DURATION (
µ
s)
RESET OCCURS
RESET DOES
NOT OCCUR
0
30
20
10
50
40
90
80
70
60
100
-50
-25
0
25
50
75
100
125
V
CC
FALLING PROPAGATION DELAY
vs. TEMPERATURE
MAX6803/04/05 toc06
TEMPERATURE (
°C)
POROPAGATION DELAY (
µ
s)
V
CC
= FALLING AT 1V/ms
V
CC
= FALLING AT 10V/ms
__________________________________________Typical Operating Characteristics
(Reset not asserted, T
A
= +25°C, unless otherwise noted.)
MAX6803/MAX6804/MAX6805
ELECTRICAL CHARACTERISTICS (continued)
(
V
CC
= full range, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at
V
CC
= +5.0V and T
A
= +25°C, reset not
asserted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
I
SOURC E
= 1µA, V
CC
1.0V
0.8
V
CC
I
SOURC E
= 200µA, V
CC
1.8V
0.8
V
CC
V
OH
Reset
asserted
I
SOURC E
= 800µA, V
CC
4.25V
0.8
V
CC
V
I
SINK
= 1.2mA, V
CC
3.0V
0.3
RESET Output Voltage
(MAX6803)
V
OL
Reset not
asserted
I
SINK
= 3.2mA, V
CC
5.0V
0.4
V
RESET Output Leakage Current
(MAX6805)
V
CC
> V
TH
, RESET not asserted
0.5
µA
Note 1: All parts are production tested at T
A
= +25°C. Over temperature limits are guaranteed by design and not production tested.
Note 2: I
SOURCE
for the MAX6803 is 100nA; I
SINK
for the MAX6804 is 100nA; I
SINK
for the MAX6805 is 50µA.
MAX6803/MAX6804/MAX6805
4-Pin, Low-Power
µP Reset Circuits with Manual Reset
4
_______________________________________________________________________________________
Pin Description
Applications Information
Manual Reset Input
Many µP-based products require manual reset capabil-
ity, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. A logic low on MR
asserts reset. Reset remains asserted while MR is low,
and for the reset active timeout period after MR returns
high. MR has an internal 20k
pullup resistor, so it can
be left unconnected if not used. Connect a normally
open momentary switch from MR to GND to create a
manual reset function; external debounce circuitry is
not required.
Interfacing to µPs with
Bidirectional Reset Pins
Since the RESET output on the MAX6805 is open-drain,
this device interfaces easily with µPs that have bidirec-
tional 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
pullup resistor allows either device to assert reset
(Figure 1).
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 Maximum Transient Duration
vs. Reset Comparator Overdrive graph. The graph
shows the maximum pulse width that a negative-going
V
CC
transient may typically have without issuing a reset
signal. As the amplitude of the transient increases, the
maximum allowable pulse width decreases.
Ensuring a Valid Reset Output
down to V
CC
= 0
When V
CC
falls below 1V and approaches the minimum
operating voltage of 0.7V, push/pull-structured reset
sinking (or sourcing) capabilities decrease drastically.
High-impedance CMOS-logic inputs connected to the
RESET pin can drift to indeterminate voltages. This
does not present a problem in most cases, since most
V
CC
V
CC
GND
MAX6805
RESET
MR
V
CC
GND
RESET
MOTOROLA
68HCXX
µP
100k
Figure 1. Interfacing to µPs with Bidirectional Reset Pins
PIN
MAX6803
MAX6804
MAX6805
NAME
FUNCTION
1
1
GND
Ground
--
2
RESET
Active-Low Reset Output. RESET is asserted while V
CC
is below the reset
threshold, or while MR is asserted. RESET remains asserted for a reset
timeout period (t
RP
) after V
CC
rises above the reset threshold or MR is
deasserted. RESET on the MAX6804 is push/pull. RESET on the MAX6805
is open-drain.
Active-High Reset Output. RESET is asserted high while V
CC
is below the
reset threshold or while MR is asserted, and RESET remains asserted for a
reset timeout period (t
RP
) after V
CC
rises above the reset threshold or MR
is deasserted. RESET on the MAX6803 is push/pull.
RESET
--
2
3
3
MR
Manual Reset Input. A logic low on MR asserts reset. Reset remains
asserted as long as MR is low, and for the reset timeout period (t
RP
) after
MR goes high. Leave unconnected or connect to V
CC
if not used.
Supply Voltage Input
V
CC
4
4
4-Pin, Low-Power
µP Reset Circuits with Manual Reset
_______________________________________________________________________________________
5
MAX6803/MAX6804/MAX6805
V
CC
GND
MAX6804
RESET
MR
100k
(a)
V
CC
GND
MAX6803
RESET
100k
*
(b)
*ASSUMES HIGH-Z RESET INPUT TO THE
µP
MR
Figure 2. Ensuring Reset Valid down to V
CC
= 0
µPs and circuitry do not operate when V
CC
drops below
1V. For the MAX6804 application where RESET must be
valid down to 0, adding a pulldown resistor between
RESET and GND removes stray leakage currents, hold-
ing RESET low (Figure 2a). The pulldown resistor value
is not critical; 100k
is large enough not to load RESET,
and small enough to pull it low. For the MAX6803, where
RESET must be valid to V
CC
= 0, a 100k
pullup resistor
between RESET and V
CC
will hold RESET high when
V
CC
falls below 0.7V (Figure 2b).
Since the MAX6805 has an open-drain, active-low out-
put, it typically uses a pullup resistor. With this device,
RESET will most likely not maintain an active condition,
but will drift to a non-active level due to the pullup
resistor and the reduced sinking capability of the open-
drain device. Therefore, this device is not recommend-
ed for applications where the RESET pin is required to
be valid down to V
CC
= 0.
1
2
4
3
V
CC
MR
(RESET)
GND
MAX6803
MAX6804
MAX6805
SOT143
TOP VIEW
RESET
( ) ARE FOR MAX6803
MAX6804
V
CC
V
CC
RESET
MR
RESET
GND
PUSHBUTTON
SWITCH
V
CC
GND
µP
Pin Configuration
Typical Operating Circuit
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