Analog Devices Inc./Maxim Integrated MAX825REUK+T

Overview

MAX825REUK+T from Maxim Integrated is a 5-pin SOT23 microprocessor supervisory circuit with manual reset input and complementary active-high reset output, designed for brownout and power-up monitoring of +2.63V supplies. It guarantees valid reset assertion down to VCC = 1V, features 140ms minimum reset timeout, 2µA supply current (SC70) / 3–8µA (SOT23), and operates across –40°C to +125°C for industrial and automotive embedded controllers.

For engineers reviewing the MAX825REUK+T datasheet, MAX825REUK+T pinout, MAX825REUK+T application, or MAX825REUK+T equivalent, key selection criteria include reset threshold accuracy (2.63V ±15mV), MR input noise immunity (100ns pulse rejection), internal 52kΩ MR pullup, watchdog absence (distinguishing it from MAX823/MAX824), and lead-free SOT23-5 packaging for high-temperature reliability.

Technical Context

The MAX825REUK+T implements a precision voltage comparator with 40ppm/°C temperature coefficient and 5mV hysteresis to detect VCC drops below 2.63V. Its reset generator enforces a guaranteed 140–280ms timeout after VCC recovery, with propagation delay under 20µs during VCC fall.

Unlike MAX823/MAX824, it omits watchdog functionality but includes both active-low RESET and active-high RESET outputs, enabling direct interface to µPs requiring either polarity. The MR input accepts CMOS logic levels and features internal pullup-no external resistor required-and asserts reset for ≥1.0µs MR pulses.

Key Specifications

Pinout & Package

MAX825REUK+T uses a 5-pin SOT23-5 package (JEDEC MO-178AA), 2.9mm × 1.6mm × 1.1mm, lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor supervisory applications.

Compared with MAX825REUK+T, MAX825SEUK+T shifts threshold upward by 300mV-critical for supply margin matching-while TLV803EB26DBVR sacrifices MR and active-high RESET to reduce cost and quiescent current, making it suitable only for minimal reset-only use cases.

Availability

MAX825REUK+T is available at Aetrix Electronics and suitable for automotive engine control units, industrial PLC modules, and battery-powered medical sensor nodes requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX825REUK+T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) designs precision analog and mixed-signal ICs for industrial, automotive, and computing applications, with emphasis on reliability and integration.

The MAX823/MAX824/MAX825 family delivers compact, low-power supervisory solutions for microprocessor reset, watchdog, and manual reset functions in space-constrained embedded systems.

FAQ

What is the exact reset threshold voltage of MAX825REUK+T and how tightly is it specified?

The MAX825REUK+T has a nominal reset threshold of 2.63V, with tolerance of ±15mV over temperature (–40°C to +125°C). This specification ensures accurate brownout detection on +2.7V supply rails while maintaining noise immunity against typical power rail ripple. The 40ppm/°C temperature coefficient further guarantees stability across its full operating range, and the 5mV hysteresis prevents chatter near the trip point. All values are production-tested and documented in Maxim's official electrical characteristics table.

Does MAX825REUK+T include a watchdog timer function?

No, MAX825REUK+T does not include a watchdog timer. It belongs to the MAX825 variant group, which provides manual reset input (MR) and complementary active-high/active-low reset outputs-but explicitly excludes the watchdog input (WDI) found in MAX823 and MAX824. This functional distinction is confirmed in the Selector Guide and Pin Description sections of the datasheet. If watchdog capability is required, MAX823REUK+T or MAX824REUK+T must be selected instead.

What is the purpose of the dual RESET outputs on MAX825REUK+T?

The MAX825REUK+T provides both active-low RESET and active-high RESET outputs to support microprocessors and peripherals with differing reset polarity requirements-such as an ARM core needing active-low reset and an FPGA configuration controller requiring active-high assertion. This eliminates the need for external inverters or level translators, simplifying layout and improving timing alignment between reset domains. Both outputs are synchronized and asserted/deasserted simultaneously, ensuring deterministic system startup behavior.

Can MAX825REUK+T operate reliably at VCC = 1.2V?

Yes, MAX825REUK+T guarantees valid reset assertion down to VCC = 1V, and its RESET outputs remain functional at VCC = 1.2V per the datasheet's Electrical Characteristics table. Specifically, VOL is specified at 0.3V (max) with ISINK = 1.2mA when VCC = VRST min, and VOH reaches 0.8×VCC under sourcing conditions. This capability enables safe operation during battery backup switchover or deep brownout scenarios where main supply collapses but backup rail sustains critical logic.

Is an external pullup resistor required for the MR pin on MAX825REUK+T?

No, an external pullup resistor is not required for the MR pin on MAX825REUK+T because it integrates a factory-trimmed 52kΩ internal pullup resistor. This allows direct connection of a momentary switch between MR and GND, with no additional components needed for basic manual reset functionality. The datasheet confirms this in the Pin Description and Detailed Description sections, noting that MR may be left open if unused-further validating the presence and sufficiency of the internal pullup.