Analog Devices Inc./Maxim Integrated MAX6328UR26+

Overview

MAX6328UR26+ from Maxim Integrated is an ultra-low-power, open-drain, active-low microprocessor reset supervisor IC designed for reliable power-on/brownout detection in 2.5V–5V digital systems. It asserts RESET when VCC falls below 2.63V (±1.5% at +25°C), holds reset for ≥100ms after VCC recovers, draws ≤1µA supply current, and operates over –40°C to +85°C - deployed in portable battery-powered controllers and automotive ECUs.

For engineers reviewing the MAX6328UR26+ datasheet, MAX6328UR26+ pinout, MAX6328UR26+ application, or MAX6328UR26+ equivalent, key selection criteria include its factory-trimmed 2.63V reset threshold, SOT23-3 open-drain output, 100ms minimum reset timeout, transient immunity up to 200µs at 100mV overdrive, and compatibility with bidirectional µP reset pins such as Motorola 68HC11.

Technical Context

The MAX6328UR26+ integrates a precision voltage comparator with hysteresis (9.5mV typical) and a temperature-stable delay timer to generate a clean, glitch-immune reset signal. Its reset threshold is factory-trimmed to 2.63V with ±1.5% tolerance at +25°C and ±2.5% over –40°C to +85°C, and exhibits 40ppm/°C tempco.

Designed for direct interface with bidirectional microcontroller reset pins, the open-drain RESET output requires an external pull-up and supports wired-OR configurations. The device remains functional down to VCC = 1V and ignores fast transients on VCC - validated by the Maximum Transient Duration vs. Reset Threshold Overdrive curve in the datasheet.

Key Specifications

Pinout & Package

SOT23-3 package: 1.3mm × 2.9mm × 1.0mm body, gull-wing leads, JEDEC MO-178AC compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TRD2T+, the MAX6328UR26+ provides essential open-drain functionality for shared reset buses, while TPS3808G12DBVR offers improved accuracy at the cost of layout incompatibility - making MAX6328UR26+ the optimal choice for drop-in upgrades in existing SOT23-3 designs requiring bidirectional reset support.

Availability

MAX6328UR26+ is available at Aetrix Electronics and suitable for industrial controllers, automotive ECUs, and portable medical devices requiring stable component supply, long-term lifecycle assurance, and lead-free compliance.

Supply support for MAX6328UR26+ 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, automotive, and computing applications.

The MAX6326/MAX6327/MAX6328 series was designed specifically for ultra-low-power, precision reset supervision in battery-critical and noise-prone embedded systems - emphasizing minimal ICC, factory-trimmed thresholds, and robust transient rejection.

FAQ

What is the exact reset threshold voltage of the MAX6328UR26+?

The MAX6328UR26+ has a factory-trimmed reset threshold of 2.63V, with ±1.5% tolerance at +25°C and ±2.5% over the full –40°C to +85°C operating range. This value is laser-trimmed during production and verified per Maxim's Electrical Characteristics table; it is not adjustable or user-configurable. The "R26" suffix in MAX6328UR26+ explicitly denotes the 2.63V variant.

Does the MAX6328UR26+ require an external pull-up resistor on the RESET pin?

Yes, the MAX6328UR26+ features an open-drain RESET output and requires an external pull-up resistor to VCC (typically 10kΩ) to establish a valid logic-high state when reset is inactive. Without this resistor, the RESET line floats and cannot drive high, violating the timing and voltage requirements of connected microcontrollers. This is inherent to its open-drain architecture and confirmed in the Pin Description section of the datasheet.

Is the MAX6328UR26+ pin-compatible with the MAX809 series?

No - while the MAX6328UR26+ shares the same SOT23-3 package outline and pin numbering (GND, RESET, VCC) with MAX809 variants, its open-drain output differs electrically from the MAX809's push-pull output. Direct substitution may cause incorrect reset behavior unless the target system expects open-drain signaling and includes the required pull-up. Pinout alignment does not imply functional or electrical compatibility.

What is the minimum VCC voltage at which the MAX6328UR26+ guarantees correct reset state?

The MAX6328UR26+ guarantees correct reset assertion and deassertion behavior down to VCC = 1.0V, as stated in the General Description and Absolute Maximum Ratings sections. Below 1.0V, the internal comparator and output stage are not characterized, and reset behavior becomes undefined. This 1V operational floor supports reliable brownout detection during severe undervoltage conditions.

How does the MAX6328UR26+ handle fast transients on the VCC supply line?

The MAX6328UR26+ rejects fast negative-going VCC transients up to 200µs in duration when the overdrive (VTH – VCC) is 100mV, as shown in the Typical Operating Characteristics graph "Maximum Transient Duration vs. Reset Threshold Overdrive." Its internal comparator incorporates filtering and hysteresis (9.5mV typical) to prevent false triggering from switching noise or ESD-induced glitches on the monitored rail.