The MAX821/MAX822SUS+T microprocessor (μP) supervisory circuits monitor power supplies in μP and digital systems. They provide excellent circuit reliability and low cost by eliminating external components and adjustments when used with 5V-powered or 3V-powered circuits. The MAX821/MAX822SUS+T also provide a power-on reset timeout delay that is pin selectable to 1ms (max), 20ms (min), or 100ms (min). These devices perform a single function: they assert a reset signal whenever the VCC supply voltage falls below a preset threshold, and they keep reset asserted for the pin-selected reset timeout delay after VCC has risen above the reset threshold. The only difference between the two devices is that the MAX821 has an active-low RESET output (which is guaranteed to be in the correct state for VCC down to 1V), while the MAX822SUS+T has an active-high RESET output. The reset comparator is designed to ignore fast transients on VCC. Reset thresholds suitable for operation with a variety of supply voltages are available. Low supply current makes the MAX821/MAX822SUS+T ideal for use in portable equipment. These devices come in a 4-pin SOT143 package.
Feature
- Pin-Selectable, Precision Power-On Reset Delay: 1ms (max), 20ms (min), or 100ms (min)
- Precision Monitoring of +3V to +5V Power-Supply Voltages
- 2.5μA Supply Current
- Guaranteed Over Temperature (-40°C to +125°C)
- Guaranteed Active-Low RESET Valid to VCC = 1V (MAX821)
- Power-Supply Transient Immunity
- No External Components
- SOT143 Package
Applications
- Bar-Code Scanners
- Computers: Desktop, Workstation, Server
- Controllers
- Critical μP and μC Power Monitoring
- Intelligent Instruments
- Portable Battery-Powered Equipment
