MAX821
4-Pin, µP Voltage Monitors with Pin-Selectable Power-On Reset Timeout Delay
4-Pin SOT Reset ICs with Selectable Reset Timeout Delay
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Overview
Features and Benefits
- 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
Product Details
The MAX821/MAX822 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/MAX822 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 MAX822 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/MAX822 ideal for use in portable equipment. These devices come in a 4-pin SOT143 package.
Applications
- Bar-Code Scanners
- Computers: Desktop, Workstation, Server
- Controllers
- Critical µP and µC Power Monitoring
- Intelligent Instruments
- Portable Battery-Powered Equipment
Product Categories
Product Lifecycle
Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Documentation & Resources
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MAX821 Reliability Data1/12/2023
Tools & Simulations
IBIS Model
IBS
MAX821L IBIS Model
49.57K
Product Recommendations
MAX821 Companion Parts
Design Resources
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