19-0433; Rev 4; 11/05
Full-Featured µP Supervisory Circuit with
±1.5% Reset Accuracy
The MAX807 microprocessor (µP) supervisory circuit
reduces the complexity and number of components
needed to monitor power-supply and battery-control functions in µP systems. A 70µA supply current makes the
MAX807 ideal for use in portable equipment, while a 2ns
chip-enable propagation delay and 250mA output current
capability (20mA in battery-backup mode) make it suitable for larger, higher-performance equipment.
The MAX807 comes in 16-pin DIP, SO, and TSSOP packages, and provides the following functions:
• µP reset. The active-low RESET output is asserted during power-up, power-down, and brownout conditions,
and is guaranteed to be in the correct state for VCC
down to 1V.
• Active-high RESET output.
• Manual-reset input.
• Two-stage power-fail warning. A separate low-line
comparator compares VCC to a threshold 52mV above
the reset threshold. This low-line comparator is more
accurate than those in previous µP supervisors.
• Backup-battery switchover for CMOS RAM, real-time
clocks, µPs, or other low-power logic.
• Write protection of CMOS RAM or EEPROM.
• 2.275V threshold detector provides for power-fail
warning and low-battery detection, or monitors a
power supply other than +5V.
• BATT OK status flag indicates that the backup-battery
voltage is above +2.275V.
• Watchdog-fault output—asserted if the watchdog input
has not been toggled within a preset timeout period.
Features
♦ Precision 4.675V (MAX807L), 4.425V (MAX807M),
or 4.575V (MAX807N) Voltage Monitoring
♦ 200ms Power-OK/Reset Time Delay
♦ RESET and RESET Outputs
♦ Independent Watchdog Timer
♦ 1µA Standby Current
♦ Power Switching
250mA in VCC Mode
20mA in Battery-Backup Mode
♦ On-Board Gating of Chip-Enable Signals;
2ns CE Gate Propagation Delay
♦ MaxCap® and SuperCap® Compatible
♦ Voltage Monitor for Power Fail
♦ Backup-Battery Monitor
♦ Guaranteed RESET Valid to VCC = 1V
♦ ±1.5% Low-Line Threshold Accuracy 52mV above
Reset Threshold
Pin Configuration
TOP VIEW
PFI 1
PFO 2
Computers
15 BATT OK
VCC 3
Applications
14 BATT
WDI
Controllers
4
MAX807
GND 5
Intelligent Instruments
Critical µP Power Monitoring
16 OUT
13 BATT ON
12 CE IN
MR
6
11 CE OUT
LOW LINE
7
10 WDO
RESET
8
9
Portable/Battery-Powered Equipment
RESET
DIP/SO/TSSOP
Ordering Information and Typical Operating Circuit appear at end of data sheet.
SuperCap is a registered trademark of Baknor Industries. MaxCap is a registered trademark of Cesiwid, Inc.
________________________________________________________________ Maxim Integrated Products
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.
1
MAX807L/M/N
General Description