19-3139; Rev 3; 1/05
Nanopower µP Supervisory Circuits with
Manual Reset and Watchdog Timer
General Description
The MAX6854/MAX6855/MAX6856/MAX6858/MAX6860–
MAX6869 ultra-low-current (170nA, typ) microprocessor
(µP) supervisory circuits combine voltage monitoring,
watchdog timer, and manual reset input functions in a 5-
pin SOT23 package. These devices assert a reset signal
whenever the monitored voltage drops below the factory-
trimmed reset threshold voltage, manual reset is assert-
ed, or the watchdog timer expires. The reset output
remains asserted for a minimum timeout period after V
CC
rises above the reset threshold and manual reset is
deasserted. Factory-trimmed reset threshold voltages
are offered from +1.575V to +4.625V in approximately
100mV increments (see
Threshold Suffix Guide).
Each
device is offered with six minimum reset timeout options,
ranging from 10ms to 1200ms.
The MAX6854/MAX6855/MAX6856/MAX6858/MAX6860–
MAX6869 are offered in a variety of configurations (see
the
Selector Guide).
The MAX6854/MAX6855/MAX6856/
MAX6861–MAX6869 provide a manual reset input,
MR.
The MAX6864–MAX6869 offer a watchdog timer that
monitors activity at the WDI input to prevent code execu-
tion errors. The MAX6864–MAX6869 offer watchdog
timeout options of 3.3s or 209s (typ). The MAX6861/
MAX6862/MAX6863 feature a pin-selectable reset delay
period of 10ms or 150ms (min). Push-pull active-low,
push-pull active-high, and open-drain active-low reset
outputs are available.
Features
o
Ultra-Low 170nA (typ) Supply Current
o
Reset Thresholds from +1.575V to +4.625V in
Approximately 100mV Increments
o
Six Minimum Reset Timeout Period Options from
10ms to 1200ms
o
Manual Reset Option
o
Watchdog Timer Option
o
Pin-Selectable 10ms/150ms (min) Reset Timeout
Period (MAX6861/MAX6862/MAX6863)
o
Immune to Short V
CC
Transients
o
Guaranteed Reset Valid to V
CC
= +1.1V
o
Three Reset Output Options:
Push-Pull
RESET
Push-Pull RESET
Open-Drain
RESET
o
No External Components
o
Small 5-Pin SOT23 Package
o
Pin Compatible to the TPS3836/TPS3837/TPS3838
(MAX6861/MAX6862/MAX6863)
MAX6854/MAX6855/MAX6856/MAX6858/MAX6860–MAX6869
Ordering Information
PART
†
MAX6854UK_
_D_-T
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
5 SOT23-5
Applications
Portable/Battery-Powered Equipment
PDAs/Cell Phones
MP3 Players/Pagers
Glucose Monitors/Patient Monitors
MAX6855UK_
_D_-T
-40°C to +85°C 5 SOT23-5
†
Insert reset threshold suffix (see Table 2, Threshold Suffix
Guide) after UK. Insert the number corresponding to the
desired reset timeout period (see Table 4, Reset Timeout
Period) after D.
Typical Operating Circuit
V
CC
0.1µF
V
CC
RESET
RESET
V
CC
Note:
Sample stock is generally held on standard versions
only (see Table 5, Standard Versions Table). Standard versions
have an order increment of 2500 pieces. Nonstandard versions
have an order increment of 10,000 pieces. Contact factory for
availability of nonstandard versions.
Pin Configurations appear at end of data sheet.
Selector Guide appears at end of data sheet.
Ordering Information continued at end of data sheet.
MAX6864
MAX6867
MANUAL
RESET
MR
GND
WDI
I/O
µP
GND
________________________________________________________________
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.
Nanopower µP Supervisory Circuits with
Manual Reset and Watchdog Timer
MAX6854/MAX6855/MAX6856/MAX6858/MAX6860–MAX6869
ABSOLUTE MAXIMUM RATINGS
V
CC
, Open-Drain
RESET
to GND ..........................-0.3V to +6.0V
MR,
Push-Pull
RESET,
RESET,
WDI, CT, I.C............................................-0.3V to (V
CC
+ 0.3V)
Input Current, Output Current (all pins)............................±20mA
Continuous Power Dissipation (T
A
= +70°C)
5-Pin SOT23 (derate 7.1mW/°C above +70°C)............571mW
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
= 1.2V to 5.5V, T
A
= -40°C to +85°C, unless otherwise specified. Typical values are at V
CC
= 2.5V, T
A
= +25°C.) (Note 1)
PARAMETER
Supply Voltage
SYMBOL
V
CC
T
A
≥
0°C
T
A
= -40°C to +85°C
V
CC
> V
TH
, no load,
reset output
deasserted (Note 2)
V
CC
= 5.0V
V
CC
= 3.3V
V
CC
= 1.8V
V
TH
-
2.5%
10
40
150
1200
300
600
CONDITIONS
MIN
1.1
1.2
210
190
170
7
V
TH
0.5
15
60
225
1800
450
900
40
0.3
0.3
0.3
0.8 x V
CC
0.8 x V
CC
25
nA
V
25
80
300
2400
600
1200
µs
ms
TYP
MAX
5.5
5.5
400
380
370
15
V
TH
+
2.5%
µA
V
%V
TH
nA
UNITS
V
Supply Current
I
CC
V
CC
< V
TH
, no load, reset output asserted
V
CC
Reset Threshold
Reset Threshold Hysteresis
V
TH
V
HYST
V
CC
falling (see Table 2)
Reset asserted to reset deasserted
D1
D2
Reset Timeout Period
t
RP
V
CC
= V
TH
+ 150mV
(Figures 2 and 3)
D3
D4
D5
D6
V
CC
to Reset Delay
t
RD
V
CC
falling from (V
TH
+ 100mV) to
(V
TH
- 100mV) at 10mV/µs
V
CC
≥
1.1V, I
SINK
= 50µA,
RESET
asserted, T
A
≥
0°C
V
OL
RESET
Output Voltage
V
CC
≥
1.2V, I
SINK
= 100µA,
RESET
asserted
V
CC
≥
2.12V, I
SINK
= 1.2mA,
RESET
asserted
V
CC
≥
1.71V, I
SOURCE
= 200µA,
RESET
deasserted, push-pull
RESET
only
V
OH
V
CC
≥
2.38V, I
SOURCE
= 500µA,
RESET
deasserted, push-pull
RESET
only
RESET
deasserted
Open-Drain
RESET
Leakage
Current
I
LKG
2
_______________________________________________________________________________________
Nanopower µP Supervisory Circuits with
Manual Reset and Watchdog Timer
MAX6854/MAX6855/MAX6856/MAX6858/MAX6860–MAX6869
Typical Operating Characteristics
(V
CC
= +2.5V, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6854 toc01
SUPPLY CURRENT
vs. TEMPERATURE
MAX6854 toc02
NORMALIZED RESET TIMEOUT PERIOD
vs. TEMPERATURE
MAX6854 toc03
10.0
V
TH
= 2.23V
0.22
0.20
0.18
I
CC
(µA)
0.16
0.14
V
CC
= 1.8V
0.12
RESET IS NOT ASSERTED
V
TH
= 1.575V
V
CC
= 3.3V
V
CC
= 5.5V
V
CC
= 2.5V
1.02
1.01
NORMALIZED t
RP
85
T
A
= +85°C
I
CC
(µA)
1.0
T
A
= +25°C
T
A
= -40°C
1.00
0.99
0.1
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
CC
(V)
0.10
-40
-15
10
35
60
TEMPERATURE (°C)
0.98
-40
-15
10
35
60
85
TEMPERATURE (°C)
NORMALIZED WATCHDOG TIMEOUT PERIOD
vs. TEMPERATURE
MAX6854 toc04
MAXIMUM V
CC
TRANSIENT DURATION
vs. RESET THRESHOLD OVERDRIVE
RESET OCCURS ABOVE THIS LINE
MAX684 toc05
1.8
1.6
NORMALIZED t
WD
1.4
1.2
1.0
0.8
0.6
1000
TRANSIENT DURATION (µs)
100
10
1
V
CC
FALLING FROM V
TH
+100mV
0.4
-40
-15
10
35
60
85
TEMPERATURE (°C)
0.1
10
100
RESET THRESHOLD OVERDRIVE (mV)
1000
NORMALIZED RESET THRESHOLD VOLTAGE
vs. TEMPERATURE
MAX6854 toc06
V
CC
TO RESET DELAY
vs. TEMPERATURE
V
CC
= V
TH
+ 100mV TO V
TH
- 100mV
60
MAX6854 toc07
1.010
70
1.005
NORMALIZED V
TH
t
RD
(µs)
-40
-15
10
35
60
85
50
1.000
40
0.995
30
0.990
TEMPERATURE (°C)
20
-40
-15
10
35
60
85
TEMPERATURE (°C)
4
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