FM811TUX

Supervisors Overview

The FM811TUX is a microprocessor supervisory circuit manufactured by Fairchild Semiconductor, housed in a compact 4-pin SOT-143 package. It provides precise voltage monitoring for 3V, 3.3V, and 5V power supplies, asserting an active-low reset signal when the supply drops below a designated threshold or the manual reset pin is forced low. The device guarantees a minimum reset pulse width of 140ms after VCC rises above the threshold. It operates with a low supply current of 6µA and maintains valid reset status down to 1.4V, requiring no external components for basic operation.

Supervisors Feature Summary

• Precision voltage monitoring for standard 3V, 3.3V, and 5V logic systems
• Active-low reset output with guaranteed 140ms minimum pulse width
• Valid reset assertion maintained at supply voltages as low as 1.4V
• Integrated manual reset input for system control without external components

Supervisors Applications

• Critical microprocessor power monitoring
• Portable equipment power management
• Intelligent instruments supervision
• Computers and printers reset circuits
• Controller system protection

Supervisors Procurement Notes

Verify the specific suffix 'TUX' against official Fairchild documentation to confirm exact tape-and-reel packaging specifications and temperature grade. Confirm end-of-life status if applicable, as legacy components may have limited availability. Ensure the active-low output configuration matches the target design requirements before procurement.

Supervisors Selection Notes

Select this component for designs requiring a simple, low-cost supervisory solution with minimal external parts. The 6µA quiescent current makes it suitable for battery-powered applications. Verify that the 1.4V operating limit aligns with the lowest expected supply voltage during brown-out conditions. The SOT-143 package offers space efficiency for dense PCB layouts.

Supervisors Part Context

The FM811 series belongs to Fairchild's family of low-cost microprocessor reset circuits. The FM811 variant specifically features an active-low reset output, distinguishing it from the FM812 which provides an active-high output. Both share identical monitoring capabilities and package options, serving as fundamental building blocks for reliable power sequencing in digital electronics.

Supervisors Replacement Considerations

The MIC809 from Micrel Semiconductor serves as a functional substitute offering similar microprocessor reset capabilities. Other alternatives include the KB862 from Kingbor Technology. Verify pin compatibility and reset threshold accuracy when substituting these parts.