Analog Devices Inc./Maxim Integrated MAX6328UR25+T

Overview

MAX6328UR25+T from Maxim Integrated is an ultra-low-power, open-drain, active-low microprocessor supervisory circuit designed to monitor 2.5V power supplies and assert a reset signal during brownout or power-up conditions. It features a factory-trimmed 2.500V reset threshold (±1.5% at +25°C), 100ms minimum reset timeout, 1µA maximum supply current at 3V, and operates over -40°C to +85°C in SOT23-3 packaging. It is used in portable battery-powered systems requiring reliable, low-quiescent-power supply monitoring.

For engineers reviewing the MAX6328UR25+T datasheet, MAX6328UR25+T pinout, MAX6328UR25+T application, or MAX6328UR25+T equivalent, key selection considerations include its open-drain active-low RESET output, 2.5V threshold accuracy across temperature, immunity to VCC transients ≤20µs at 100mV overdrive, compatibility with bidirectional µP reset pins, and drop-in replacement capability for MAX809/MAX810 in 2.5V systems.

Technical Context

The MAX6328UR25+T implements a precision bandgap-based reset comparator with 2.5V factory-trimmed threshold, ±2.5% tolerance over -40°C to +85°C, and 40ppm/°C tempco. Its internal timing circuit guarantees ≥100ms reset assertion after VCC rises above threshold, with delay stability verified down to VCC = 1.2V.

As an open-drain device, MAX6328UR25+T requires an external pull-up resistor on RESET and supports wired-OR configurations-enabling direct interface with microcontrollers like the Motorola 68HC11 that feature bidirectional reset pins. Its 1µA max ICC eliminates need for power gating in always-on monitoring paths.

Key Specifications

Pinout & Package

MAX6328UR25+T is housed in a 3-pin SOT23-3 package (outline 21-0051), with 0.95mm pitch, 2.9mm × 1.6mm footprint, and gull-wing leads compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TR25+T and TPS3808G12DBVR, MAX6328UR25+T uniquely balances ultra-low 1µA ICC, open-drain flexibility, and proven transient immunity-making it optimal for space- and energy-constrained 2.5V systems where minimal BOM and deterministic reset behavior are critical.

Availability

MAX6328UR25+T is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, and smart meter battery backup systems requiring stable component supply, long-lifecycle availability, and RoHS-compliant sourcing.

Supply support for MAX6328UR25+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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, communications, and consumer applications.

The MAX6328UR25+T belongs to the MAX6326/MAX6327/MAX6328 family of ultra-low-power µP supervisors, engineered specifically for reliable, zero-calibration power monitoring in battery-critical and space-constrained embedded systems.

FAQ

What is the exact reset threshold voltage of MAX6328UR25+T and how does it vary with temperature?

The MAX6328UR25+T has a factory-trimmed nominal reset threshold of 2.500V at +25°C, with ±1.5% tolerance at room temperature and ±2.5% over the full -40°C to +85°C operating range. Its temperature coefficient is 40ppm/°C, meaning threshold drift is bounded and predictable-e.g., maximum deviation is approximately ±20mV across the temperature range. This ensures robust 2.5V supply monitoring without recalibration.

Does MAX6328UR25+T require any external components to operate?

No, MAX6328UR25+T requires no external components for basic reset supervision. It integrates the voltage reference, comparator, timing capacitor, and open-drain output driver. Only an external pull-up resistor on the RESET pin is needed-typically 10kΩ to VCC-to establish the high state when not asserted. No capacitors, resistors, or trimming elements are necessary.

Can MAX6328UR25+T interface directly with a microcontroller that has a bidirectional reset pin?

Yes, MAX6328UR25+T's open-drain RESET output is explicitly designed for this use case. When connected directly to a bidirectional µP reset pin (e.g., Motorola 68HC11) with a single external pull-up resistor, either the MAX6328UR25+T or the µP can assert reset-enabling coordinated system-level reset control without additional logic or level shifters.

What is the maximum supply voltage the MAX6328UR25+T can monitor, and what happens below minimum VCC?

MAX6328UR25+T monitors VCC from 1.2V to 5.5V. Below 1.2V, the device is not guaranteed to maintain correct reset state; however, it remains functional down to 1.0V at 0°C to +70°C per Absolute Maximum Ratings. The reset comparator is specified to operate correctly down to VCC = 1.2V across the full -40°C to +85°C range, ensuring reliable brownout detection even during deep undervoltage events.

Is MAX6328UR25+T pin-compatible with older Maxim reset supervisors like MAX809?

Yes, MAX6328UR25+T is pin-compatible with MAX809R25 in SOT23-3 packaging and shares identical pinout (VCC, RESET, GND). However, MAX809R25 uses a push-pull output, whereas MAX6328UR25+T uses open-drain-so a design change (adding pull-up) is required for functional equivalence. For drop-in replacement with identical electrical behavior, MAX6328UR25+T replaces MAX809R25 only when open-drain functionality is desired or accommodated.