Analog Devices Inc./Maxim Integrated MAX6328UR22+T

Overview

MAX6328UR22+T from Maxim Integrated is an ultra-low-power, open-drain, active-low microprocessor supervisory circuit in SOT23-3 package. It monitors VCC supply voltage and asserts reset when VCC drops below 2.20V (±2.5% over temperature), holding reset for ≥100ms after VCC recovers. Designed for portable/battery-powered systems, it draws ≤1µA at 3V and operates from 1.2V to 5.5V.

For engineers reviewing the MAX6328UR22+T datasheet, MAX6328UR22+T pinout, MAX6328UR22+T application, or MAX6328UR22+T equivalent, key selection factors include its 2.20V factory-trimmed reset threshold, open-drain output compatible with bidirectional µP reset pins (e.g., Motorola 68HC11), 100ms minimum reset timeout, immunity to fast VCC transients, and SOT23-3 footprint compatibility with MAX803/MAX809/MAX810.

Technical Context

The MAX6328UR22+T implements a precision bandgap-based reset comparator with 40ppm/°C tempco and 6.3mV hysteresis, ensuring stable threshold behavior across -40°C to +85°C. Its internal timing circuit guarantees ≥100ms reset assertion after power-up or brownout recovery, independent of external components.

As an open-drain device, MAX6328UR22+T requires an external pull-up resistor on RESET to interface with µPs having bidirectional reset pins. It ignores negative-going VCC transients shorter than ~100µs at 200mV overdrive, enhancing noise immunity in noisy power environments.

Key Specifications

Pinout & Package

MAX6328UR22+T is housed in a 3-pin SOT23-3 package with gull-wing leads, JEDEC MO-178AA compliant, RoHS-compliant (lead-free).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TRD2+T and TPS3808G01DBVR, MAX6328UR22+T uniquely delivers 2.20V precision reset, open-drain output, and true 3-pin SOT23-3 compatibility-enabling seamless integration into space-constrained, battery-sensitive designs with bidirectional µP interfaces without layout changes.

Availability

MAX6328UR22+T is available at Aetrix Electronics and suitable for portable power management, industrial controller monitoring, embedded µP boot integrity, legacy µP interface, and battery-backed real-time clock supervision requiring stable component supply and long-term lifecycle support.

Supply support for MAX6328UR22+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 high-performance analog and mixed-signal semiconductor solutions for industrial, communications, computing, and consumer markets.

The MAX632x family was engineered specifically for ultra-low-power microprocessor supervision in battery-critical applications, emphasizing minimal ICC, factory-trimmed accuracy, and robust transient immunity in miniature 3-pin packages.

FAQ

What is the exact reset threshold voltage of MAX6328UR22+T and how stable is it over temperature?

The MAX6328UR22+T has a factory-trimmed nominal reset threshold of 2.20V, specified as 2.145V (min) to 2.250V (max) over the full -40°C to +85°C operating range. Its temperature coefficient is 40ppm/°C, meaning threshold drift is limited to ±0.018V across the entire temperature span - ensuring consistent brownout detection without recalibration.

Does MAX6328UR22+T require any external components to function as a reset supervisor?

No, MAX6328UR22+T operates as a fully self-contained reset supervisor with no external components required for basic functionality. Only a single external pull-up resistor on the open-drain RESET pin is needed for proper logic-level translation - typically 10kΩ to VCC - making it significantly simpler than RC-based reset circuits.

Can MAX6328UR22+T be used with microcontrollers that have bidirectional reset pins?

Yes, MAX6328UR22+T is explicitly designed for this use case. Its open-drain RESET output allows direct connection to bidirectional µP reset pins (e.g., Motorola 68HC11) using one pull-up resistor. Either the MAX6328UR22+T or the µP can assert reset on the shared line, enabling flexible system-level reset coordination without additional logic.

What is the maximum VCC supply voltage rating for MAX6328UR22+T and what happens below 1.2V?

MAX6328UR22+T is rated for VCC from 1.2V to 5.5V. Below 1.2V, the device is not guaranteed to operate correctly: the reset comparator may become unstable, and the output state is undefined. However, all six MAX632x/MAX634x variants - including MAX6328UR22+T - are guaranteed to hold correct reset state down to 1.0V at room temperature per Absolute Maximum Ratings.

How does MAX6328UR22+T handle fast voltage transients on the VCC line?

MAX6328UR22+T incorporates inherent transient immunity: its reset comparator is designed to ignore fast negative-going VCC transients. For example, at 200mV overdrive (i.e., VCC dipping 200mV below 2.20V), it rejects glitches shorter than ~100µs - preventing false resets in electrically noisy environments such as motor drives or switch-mode power supplies.