Document
19-3139; Rev 2; 9/04
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 5pin SOT23 package. These devices assert a reset signal whenever the monitored voltage drops below the factorytrimmed reset threshold voltage, manual reset is asserted, or the watchdog timer expires. The reset output remains asserted for a minimum timeout period after VCC 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 execution 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
♦ 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 ♦ Pin-Selectable 10ms/150ms (min) Reset Timeout Period (MAX6861/MAX6862/MAX6863) ♦ Immune to Short VCC Transients ♦ Guaranteed Reset Valid to VCC = +1.1V ♦ Three Reset Output Options: Push-Pull RESET Push-Pull RESET Open-Drain RESET ♦ No External Components ♦ Small 5-Pin SOT23 Package ♦ 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
VCC 0.1µF VCC RESET RESET VCC
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 she.