19-3139; Rev 3; 1/05
Nanopower µP Supervisory Circuits with
Manual Reset and Watchdog Timer
General Description
Features
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
ꢀ Ultra-Low 170nA (typ) Supply Current
ꢀ Reset Thresholds from +1.575V to +4.625V in
Approximately 100mV Increments
ꢀ Six Minimum Reset Timeout Period Options from
10ms to 1200ms
ꢀ Manual Reset Option
ꢀ Watchdog Timer Option
remains asserted for a minimum timeout period after V
CC
ꢀ Pin-Selectable 10ms/150ms (min) Reset Timeout
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.
Period (MAX6861/MAX6862/MAX6863)
ꢀ Immune to Short VCC Transients
ꢀ Guaranteed Reset Valid to VCC = +1.1V
ꢀ Three Reset Output Options:
Push-Pull RESET
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.
Push-Pull RESET
Open-Drain RESET
ꢀ No External Components
ꢀ Small 5-Pin SOT23 Package
ꢀ Pin Compatible to the TPS3836/TPS3837/TPS3838
(MAX6861/MAX6862/MAX6863)
Ordering Information
†
PART
TEMP RANGE PIN-PACKAGE
-40°C to +85°C 5 SOT23-5
-40°C to +85°C 5 SOT23-5
Applications
Portable/Battery-Powered Equipment
MAX6854UK_ _D_-T
MAX6855UK_ _D_-T
PDAs/Cell Phones
†
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.
MP3 Players/Pagers
Glucose Monitors/Patient Monitors
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.
Typical Operating Circuit
V
CC
0.1 F
V
V
CC
CC
Pin Configurations appear at end of data sheet.
Selector Guide appears at end of data sheet.
Ordering Information continued at end of data sheet.
RESET
RESET
P
MAX6864
MAX6867
MR
I/O
WDI
MANUAL
RESET
GND
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.