Analog Devices Inc./Maxim Integrated MAX6328XR31+

Overview

MAX6328XR31+ from Maxim Integrated is an ultra-low-power open-drain microprocessor reset supervisor IC designed to monitor 3.08V power supplies in embedded systems. It asserts an active-low RESET signal when VCC falls below 3.08V (±1.5% at +25°C, ±2.5% over -40°C to +85°C), holds reset for ≥100ms after VCC recovers, and draws ≤1µA supply current. It operates down to 1V VCC and rejects fast transients, making it suitable for battery-powered portable equipment with strict power and reliability requirements.

For engineers reviewing the MAX6328XR31+ datasheet, MAX6328XR31+ pinout, MAX6328XR31+ application, or MAX6328XR31+ equivalent, key selection criteria include its factory-trimmed 3.08V reset threshold, SC70-3 open-drain output configuration, guaranteed operation from -40°C to +85°C, transient immunity up to 200µs at 100mV overdrive, and compatibility with bidirectional µP reset pins such as those on Motorola 68HC11 controllers.

Technical Context

The MAX6328XR31+ implements a precision bandgap-based voltage comparator with hysteresis (9.5mV typical) to detect VCC drops below its 3.08V threshold. Its internal timing circuit ensures a minimum 100ms reset timeout after VCC recovery, independent of external components.

As an open-drain device, MAX6328XR31+ requires an external pull-up resistor to interface with µP reset inputs and supports wired-OR configurations. Its reset assertion logic is active-low, and the output remains valid down to VCC = 1V - enabling reliable brownout detection even during deep power collapse.

Key Specifications

Pinout & Package

MAX6328XR31+ is housed in a 3-pin SC70 package (2.0mm × 2.1mm × 0.9mm), optimized for space-constrained PCB layouts in portable electronics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TR31+T and TPS3808G33DBVR, the MAX6328XR31+ offers optimal trade-off for space- and power-constrained designs needing open-drain flexibility and minimal external components - especially where bidirectional reset control or reset bus arbitration is required.

Availability

MAX6328XR31+ is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, automotive body control units, and smart utility meters requiring stable component supply, long-lifecycle support, and consistent parametric performance across temperature.

Supply support for MAX6328XR31+ 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, automotive, communications, and computing markets.

The MAX6326/MAX6327/MAX6328 family was designed specifically for ultra-low-power microprocessor supervision in battery-operated and energy-sensitive systems - delivering precision reset functionality in minimal footprint without external components.

FAQ

What is the exact reset threshold voltage of MAX6328XR31+ and how tightly is it specified?

The MAX6328XR31+ has a factory-trimmed reset threshold of 3.08V, with a tolerance of ±1.5% at +25°C and ±2.5% over the full operating temperature range of -40°C to +85°C. This specification is guaranteed by production testing and ensures reliable brownout detection for 3.0V/3.3V rails without external calibration. The MAX6328XR31+ achieves this precision using laser-trimmed internal resistors within its voltage reference circuit.

Does MAX6328XR31+ require an external pull-up resistor, and why?

Yes, MAX6328XR31+ requires an external pull-up resistor on its open-drain RESET pin because its output stage lacks an internal pull-up. This design allows system designers to select the pull-up voltage independently (e.g., 1.8V, 3.3V, or 5V) to match the logic level of the target microprocessor's reset input. The MAX6328XR31+ datasheet specifies that the pull-up value should be chosen to ensure proper rise time and noise margin while limiting sink current to ≤100µA during reset assertion.

Can MAX6328XR31+ operate reliably when VCC drops below 2.0V?

Yes, MAX6328XR31+ is fully functional and guarantees correct reset assertion down to VCC = 1.0V - well below 2.0V. Its internal bandgap reference and comparator remain stable across this range, enabling robust brownout detection during deep battery discharge or power supply failure. This capability is explicitly tested and guaranteed per the Absolute Maximum Ratings and Electrical Characteristics tables in the MAX6328XR31+ datasheet.

How does MAX6328XR31+ reject short power supply transients?

MAX6328XR31+ incorporates internal filtering and comparator hysteresis (9.5mV typical) to ignore fast negative-going VCC transients. Its datasheet specifies maximum allowable glitch durations - for example, a 100mV overdrive (i.e., VCC dipping 100mV below 3.08V) is rejected if shorter than ~140µs at +25°C. This prevents false resets from switching regulator noise or ESD-induced supply disturbances, and the behavior is characterized across temperature in the Typical Operating Characteristics plots.

Is MAX6328XR31+ pin-compatible with other members of the MAX632x family?

Yes, MAX6328XR31+ shares identical pinout (SC70-3), footprint, and terminal functions with all MAX6326/MAX6327/MAX6328 variants - differing only in reset threshold and output type (open-drain vs. push-pull). This allows direct substitution within the same package variant (e.g., replacing MAX6328XR25+ with MAX6328XR31+) without PCB changes, provided the application requires the 3.08V threshold and open-drain output behavior of the MAX6328XR31+.