Union Semiconductor UM821RBE

The UM807/821/822 are low-power microprocessor (μP) supervisory circuits used to 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 UM807/821/822 also provide a debounced manual reset input with long setup period. On all devices, the reset output asserts when the VCC supply voltage drops below its specified threshold. The reset output remains asserted for the reset timeout period (240ms typ) after VCC rises above the reset threshold. The reset output is one-shot pulse asserted for the reset timeout period (140ms min) when manual reset input is held low for a fixed setup timeout period. These devices ignore manual reset transitions of less than the fixed setup timeout period. The UM807 has an active-low RESET with open-drain output, the UM821 has an active-low RESET with push-pull output, and the UM822 has an active-high RESET with push-pull output. These devices, offered in small SOT143 package, are fully guaranteed over the extended temperature range (-40°C to +85°C).

• No External Components
• VCC Transient Immunity
• Correct Logic Output Guaranteed to VCC = 1.0V
• Precision VCC Monitoring of 3.0V, 3.3V and 5.0V Supplies
• 2μA Supply Current
• 140ms Minimum Power-On Reset Pulse Width
• Available in 3 Manual Reset Setup Periods (tMR): A: 10.08s B: 6.72s C: 1.68s
• Available in 3 Output Configurations: Open-Drain Active-Low RESET Output (UM807); Push-Pull Active-Low RESET Output (UM821); Push-Pull Active-High RESET Output (UM822)
• 4-Pin SOT143 Package
• Wide Operation Temperature: -40°C to +85°C

• Set-Top Boxes
• Consumer Electronics
• DVD Players
• Cable/DSL Modems
• MP3 Players
• Industrial Equipments
• Automotive
• Medical Devices