Maxim Integrated MXD1818UR31 Microprocessor Reset Circuit

The MXD1818UR31 from Maxim Integrated is a compact, highly reliable microprocessor (µP) supervisory circuit designed to monitor power supplies in µP and digital systems. It provides a crucial function by asserting a reset signal to the µP during power-up, power-down, and brown-out conditions, ensuring that the µP starts up in a known state every time.

This device is particularly suitable for portable and space-constrained applications due to its ultra-small SOT-323 package. The MXD1818UR31 operates over a wide voltage range, making it versatile for various system configurations and ensuring compatibility with many microprocessors and digital systems.

Key Features

• Reset Threshold Levels: The MXD1818UR31 comes with a preset factory-trimmed V<sub>CC reset threshold level of 3.08V, which is suitable for operation with standard 3.3V power supplies.
• Low Power Consumption: With its low supply current of only 1.6µA (typical), the device is an excellent choice for battery-operated equipment where power efficiency is critical.
• Reset Output Stage: The reset output is active low and can sink a current of 5.5mA, ensuring that the reset signal is clearly communicated to the target µP even under load.
• Manual Reset Input: An additional feature is the manual reset input, which allows for an external trigger of the reset signal, providing an extra layer of system control.
• Reset Timeout: After the supply voltage returns to an acceptable level, the MXD1818UR31 maintains the reset signal for a minimum timeout period of 140ms (typical), ensuring the µP has sufficient time to stabilize.

Applications

The MXD1818UR31 is ideal for a wide range of applications where reliable system reset functionality is required. It is commonly used in:

• Computers and Servers
• Embedded Systems
• Portable/Battery-Powered Devices
• Data Storage Equipment
• Industrial Controllers

In summary, the Maxim Integrated MXD1818UR31 is a robust µP reset circuit that provides essential protective features for digital systems, ensuring proper operation through various supply conditions. Its low power consumption, small footprint, and precision reset capabilities make it a go-to choice for designers looking to enhance system reliability.