Analog Devices Inc./Maxim Integrated MAX6328UR29+T

Overview

MAX6328UR29+T from Maxim Integrated is an ultra-low-power open-drain microprocessor supervisory circuit that monitors VCC supply voltage and asserts an active-low reset signal when voltage falls below 2.93V, maintaining reset for ≥100ms after recovery - used in battery-powered µP systems requiring reliable power-on/brownout detection.

For engineers reviewing the MAX6328UR29+T datasheet, MAX6328UR29+T pinout, MAX6328UR29+T application, or MAX6328UR29+T equivalent, key selection factors include its 2.93V factory-trimmed reset threshold, 1µA max supply current at +25°C, SOT23-3 package, open-drain output with 0.3V VOL at 1.6mA sink, and guaranteed operation down to VCC = 1.2V over –40°C to +85°C.

Technical Context

The MAX6328UR29+T implements a precision bandgap-based reset comparator with 2.5% temperature drift (–40°C to +85°C) and 40ppm/°C tempco, designed to ignore fast VCC transients ≤20µs at 200mV overdrive. Its internal hysteresis is fixed at 6.3mV to prevent chatter near threshold.

As an open-drain device, it requires an external pull-up resistor for RESET logic level translation and supports bidirectional µP reset pins (e.g., Motorola 68HC11), enabling either the supervisor or host processor to assert system reset without contention.

Key Specifications

Pinout & Package

SOT23-3 package: 3-pin surface-mount, 1.3mm height, RoHS-compliant lead-free construction (indicated by "+T" suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6326UR29+T, the MAX6328UR29+T trades push-pull drive for open-drain flexibility and lower system-level component count; versus TPS3808G33DBVR, it offers lower quiescent current and native support for bidirectional µP reset pins - critical in legacy controller designs.

Availability

MAX6328UR29+T is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, smart energy meters, and automotive body control units requiring stable component supply and long-term lifecycle support.

Supply support for MAX6328UR29+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, mixed-signal, and power management ICs for industrial, computing, and consumer applications.

The MAX632x family delivers ultra-low-power µP supervisory circuits optimized for battery longevity and robust brownout immunity in space-constrained embedded systems.

FAQ

What is the exact reset threshold voltage of the MAX6328UR29+T and how tightly is it specified?

The MAX6328UR29+T has a factory-trimmed nominal reset threshold of 2.93V, with ±1.5% tolerance at +25°C and ±2.5% over the full –40°C to +85°C operating range. This specification is guaranteed per datasheet Electrical Characteristics table and applies directly to the MAX6328UR29+T - no external calibration is needed.

Does the MAX6328UR29+T require an external pull-up resistor on the RESET pin?

Yes, the MAX6328UR29+T features an open-drain RESET output and requires an external pull-up resistor to a valid logic rail (e.g., VCC or higher). Typical values range from 10kΩ to 100kΩ depending on bus capacitance and rise-time requirements - this is a defining characteristic of the MAX6328UR29+T versus its push-pull counterparts.

Can the MAX6328UR29+T operate reliably at VCC = 1.2V?

Yes, the MAX6328UR29+T is fully specified to operate down to VCC = 1.2V over –40°C to +85°C, and its reset comparator remains functional and monotonic throughout this range. This behavior is explicitly guaranteed in the Absolute Maximum Ratings and Electrical Characteristics sections for the MAX6328UR29+T.

How does the MAX6328UR29+T handle short voltage transients on the VCC line?

The MAX6328UR29+T incorporates transient immunity circuitry that ignores negative-going VCC glitches shorter than ~20µs when overdriven by 200mV below threshold - a key design feature confirmed in the Typical Operating Characteristics graphs. This ensures the MAX6328UR29+T does not generate spurious resets during switching noise or ESD events.

Is the MAX6328UR29+T pin-compatible with older Maxim reset supervisors like the MAX809?

Yes, the MAX6328UR29+T is pin-compatible with MAX809-series devices in SOT23-3 packaging, sharing identical pinout (VCC, RESET, GND) and footprint. However, the MAX6328UR29+T offers significantly lower supply current (1µA vs. 20µA) and tighter threshold accuracy - making it a direct drop-in upgrade where ultra-low power is critical.