Analog Devices Inc./Maxim Integrated MAX6328UR28

Overview

MAX6328UR28 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 2.800V 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 MAX6328UR28 datasheet, MAX6328UR28 pinout, MAX6328UR28 application, or MAX6328UR28 equivalent, this page provides verified technical context, pin-level design meaning, real-world use scenarios, and validated alternative options for µP reset circuit selection in space-constrained, low-power embedded designs.

Technical Context

The MAX6328UR28 implements a precision bandgap-based reset comparator with hysteresis (6.3mV) and internal timing control to guarantee ≥100ms reset assertion after VCC rises above the 2.800V threshold. Its open-drain RESET output requires an external pull-up and supports bidirectional µP reset interfaces like the Motorola 68HC11.

It is immune to fast VCC transients - the reset comparator ignores negative-going glitches up to duration limits defined by reset threshold overdrive (e.g., ≤20µs for 100mV overdrive). Fully specified from -40°C to +85°C, it maintains reset accuracy and ultra-low ICC (≤1.0µA typical at 3V) across temperature and supply range.

Key Specifications

Pinout & Package

MAX6328UR28 is housed in a 3-pin SOT23-3 package (package code U3-1, outline 21-0051), with 1.3mm × 2.9mm footprint and 0.95mm height - compatible with high-density PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809SUR29-T and TPS3808G12DBVR, the MAX6328UR28 uniquely combines factory-trimmed 2.800V accuracy, open-drain output, and 1µA max ICC in a 3-pin SOT23 - making it optimal for space- and power-constrained designs needing robust, component-free reset supervision at standard logic rail voltages.

Availability

MAX6328UR28 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 MAX6328UR28 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and consumer applications.

The MAX6326/MAX6327/MAX6328 family was designed specifically for ultra-low-power, pin-compatible microprocessor reset supervision in battery-operated and space-constrained embedded systems - delivering precision voltage monitoring without external components.

FAQ

What is the exact reset threshold voltage of MAX6328UR28 and how does it vary with temperature?

The MAX6328UR28 has a factory-trimmed nominal reset threshold of 2.800V. At +25°C, this is guaranteed within ±1.5% (2.758V to 2.842V). Over the full operating temperature range of -40°C to +85°C, the threshold varies by ±2.5%, resulting in a min–max span of 2.730V to 2.870V. Its tempco is 40ppm/°C, contributing predictably to this drift.

Does MAX6328UR28 require an external pull-up resistor on the RESET pin?

Yes, MAX6328UR28 features an open-drain RESET output and requires an external pull-up resistor to a valid voltage rail (e.g., VCC or another logic supply). Typical values range from 10kΩ to 100kΩ depending on bus capacitance and rise-time requirements. Without this resistor, the RESET signal cannot go high and the supervised µP will remain held in reset.

Can MAX6328UR28 operate reliably during deep battery discharge down to 1.2V?

Yes, MAX6328UR28 is fully specified to operate and maintain correct reset state down to VCC = 1.2V over temperature. Its internal circuitry remains functional and asserts RESET as long as VCC stays below 2.800V - including during severe brownout or battery depletion scenarios where other supervisors may lose regulation or fail to assert.

Is MAX6328UR28 pin-compatible with older Maxim reset ICs like MAX809?

Yes, MAX6328UR28 uses the same 3-pin SOT23-3 package and identical pinout (VCC, RESET, GND) as MAX809-series devices. However, MAX809 has a push-pull output and different threshold options - so while PCB layout is interchangeable, the open-drain behavior of MAX6328UR28 requires verification of pull-up presence and bus topology compatibility.

What is the maximum transient duration that MAX6328UR28 can ignore on the VCC line?

MAX6328UR28 rejects VCC transients based on overdrive magnitude: for a 100mV overdrive (i.e., VCC dipping 100mV below 2.800V), it ignores glitches ≤20µs. As overdrive increases (e.g., 200mV), the allowable duration decreases - down to ~5µs. This immunity prevents false resets from switching noise, ESD, or coupling in electrically harsh environments.