Analog Devices Inc./Maxim Integrated MAX6328UR24

Overview

MAX6328UR24 from Maxim Integrated is an ultra-low-power open-drain microprocessor supervisory circuit designed to monitor VCC supply voltage and assert an active-low reset signal during power-up, power-down, or brownout conditions. It features a factory-trimmed 2.400V reset threshold (±1.5% at +25°C, ±2.5% over –40°C to +85°C), 100ms minimum reset timeout, 1µA max supply current at 3V, and operates from 1.2V to 5.5V. It is used in portable battery-powered systems requiring reliable, low-quiescent-power reset supervision.

For engineers reviewing the MAX6328UR24 datasheet, MAX6328UR24 pinout, MAX6328UR24 application, or MAX6328UR24 equivalent, this page delivers verified electrical parameters, SOT23-3 package details, open-drain output behavior, temperature-stable reset timing, and direct alternatives for µP reset circuit design.

Technical Context

The MAX6328UR24 implements a precision bandgap-based reset comparator with 40ppm/°C tempco and 6.3mV hysteresis, ensuring stable threshold detection across temperature. Its internal circuitry guarantees correct reset state down to VCC = 1.2V and ignores fast transients via built-in immunity design.

As an open-drain variant in the MAX632x family, it requires an external pull-up resistor and interfaces directly with bidirectional µP reset pins (e.g., Motorola 68HC11). The device asserts RESET low when VCC falls below 2.400V and holds it for ≥100ms after VCC rises above threshold.

Key Specifications

Pinout & Package

MAX6328UR24 is housed in a 3-pin SOT23-3 package (package code U3-1), with 1.3mm × 2.9mm footprint and gull-wing leads. Pin 1 = GND, Pin 2 = RESET (open-drain), Pin 3 = VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6328UR24, MAX809SUR24-T offers simpler interface but loses open-drain flexibility, while TPS3808G33DBVR trades threshold accuracy and ultra-low ICC for programmable timing - making MAX6328UR24 optimal for fixed-threshold, battery-constrained, bidirectional-reset applications.

Availability

MAX6328UR24 is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, smart meter communication units, and automotive body control modules requiring stable component supply, long-lifecycle support, and RoHS-compliant sourcing.

Supply support for MAX6328UR24 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, computing, and communications applications, with emphasis on power efficiency and integration.

The MAX632x series was developed specifically for ultra-low-power microprocessor reset supervision in space-constrained, battery-operated, and industrial embedded systems - prioritizing sub-µA ICC, factory-trimmed thresholds, and robust transient immunity.

FAQ

What is the exact reset threshold voltage of MAX6328UR24 and how does it vary with temperature?

The MAX6328UR24 has a factory-trimmed nominal reset threshold of 2.400V, with ±1.5% tolerance at +25°C and ±2.5% over the full –40°C to +85°C operating range. Its temperature coefficient is 40ppm/°C, meaning threshold drift is limited to approximately ±10mV across the industrial temperature span. This ensures predictable brownout response in battery-powered and industrial environments where supply rails fluctuate with temperature.

Does MAX6328UR24 require an external pull-up resistor, and what value is recommended?

Yes, MAX6328UR24 requires an external pull-up resistor on its open-drain RESET pin because it cannot drive high actively. A 10kΩ to 100kΩ resistor to the target logic rail (e.g., 3.3V or 2.4V) is typical. For 1.6mA sink capability and <0.3V low-level voltage, a 10kΩ pull-up yields ~16µA static current - balancing speed, noise immunity, and power. The exact value depends on bus capacitance and µP input leakage.

Can MAX6328UR24 operate reliably below 2.4V, and what is its minimum functional VCC?

Yes, MAX6328UR24 remains fully functional down to VCC = 1.2V over temperature, and its internal reset comparator is guaranteed to hold correct state (i.e., assert RESET) for VCC as low as 1.0V. This allows it to supervise deeply undervolted systems and ensures clean reset assertion even during severe brownout events - critical for data integrity in µP-based logging and control applications.

How does the 100ms reset timeout of MAX6328UR24 behave across temperature and supply voltage?

The MAX6328UR24 guarantees a minimum 100ms reset timeout after VCC rises above threshold, with typical values ranging from 100ms to 280ms depending on temperature and VCC. At +25°C and VCC = 3.3V, it is typically 185ms; worst-case (–40°C or +85°C) remains ≥100ms per specification. This margin ensures compatibility with all common µPs requiring ≥100ms power-on reset, regardless of environmental conditions.

Is MAX6328UR24 pin-compatible with other members of the MAX632x family, and which ones share the same pinout?

Yes, MAX6328UR24 is pin-compatible with all SOT23-3 variants in the MAX632x/MAX634x family, including MAX6326URxx, MAX6327URxx, MAX6346URxx, MAX6347URxx, and MAX6348URxx. All use identical 3-pin SOT23-3 layout (GND–RESET–VCC), enabling drop-in substitution within the same output type group - though open-drain (MAX6328/MAX6348) and push-pull (MAX6326/MAX6346) variants differ electrically and require matching output topology in the system design.