Full-Featured µP Supervisory Circuit with ±1.5% Reset Accuracy

 

Part Number	Replacement	Explanation

Description

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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 V_CC down to 1V.

Active-high RESET output.

Manual-reset input.

Two-stage power-fail warning. A separate low-line comparator compares V_CC 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.

MAX807L, MAX807M, MAX807N: Typical Operating Circuit Enlarge+

Key Features

• Precision 4.675V (MAX807L), 4.425V (MAX807M), or 4.575V (MAX807N) Voltage Monitoring
• 200ms Power-OK/Reset Time Delay
• RESET-bar and RESET Outputs
• Independent Watchdog Timer
• 1µA Standby Current
• Power Switching
  • 250mA in V_CC 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 active-low RESET Valid to V_CC = 1V
• ±1.5% Low-Line Threshold Accuracy 52mV above Reset Threshold

Applications/Uses

• Computers: Desktop, Workstation, Server
• Controllers
• Critical µP Monitoring
• Intelligent Instruments
• Portable Battery-Powered Equipment