Analog Devices Inc./Maxim Integrated MAX6328UR23

Overview

MAX6328UR23 from Maxim Integrated is an ultra-low-power open-drain microprocessor reset supervisor IC designed to monitor 2.3V power supplies in embedded digital systems. It asserts an active-low reset signal when VCC falls below 2.32V (±1.5% at +25°C), holds reset for ≥100ms after VCC recovers, and draws ≤1µA supply current - enabling reliable brownout protection in battery-powered controllers and portable instrumentation.

For engineers reviewing the MAX6328UR23 datasheet, MAX6328UR23 pinout, MAX6328UR23 application, or MAX6328UR23 equivalent, this device delivers precision voltage monitoring with transient immunity, factory-trimmed threshold accuracy, and SOT23-3 compatibility for space-constrained µP reset circuits requiring minimal quiescent current and no external components.

Technical Context

The MAX6328UR23 implements a precision bandgap-based voltage comparator with hysteresis (9.5mV typical) to reject fast VCC transients up to 100µs duration at 200mV overdrive. Its reset timeout is guaranteed over -40°C to +85°C with ±40ppm/°C tempco, and it remains functional down to VCC = 1V - ensuring valid reset state during deep undervoltage conditions.

This device uses open-drain RESET output compatible with bidirectional µP reset pins (e.g., Motorola 68HC11), requiring only an external pull-up resistor. Unlike push-pull variants, it avoids bus contention in multi-source reset architectures and supports wired-OR configurations without level-shifting circuitry.

Key Specifications

Pinout & Package

MAX6328UR23 is housed in a 3-pin SOT23-3 package (JEDEC MO-178AA), with 1.3mm × 2.9mm footprint and 1.45mm height - optimized for high-density PCB layouts in portable and space-constrained applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6328UR23, the MAX6328UR24-T offers a 80mV higher reset threshold for improved noise margin on 2.4V rails, while MAX809SUR23-T trades open-drain capability and lower current for slightly relaxed threshold accuracy and push-pull drive - making MAX6328UR23 optimal for battery-sensitive, multi-source reset architectures.

Availability

MAX6328UR23 is available at Aetrix Electronics and suitable for industrial controllers, portable medical devices, and automotive body control modules requiring stable component supply, long-term lifecycle support, and guaranteed factory-trimmed voltage thresholds.

Supply support for MAX6328UR23 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, and computing applications.

The MAX6326/MAX6327/MAX6328 series was designed specifically for ultra-low-power microprocessor reset supervision in battery-operated and space-constrained systems - delivering precision voltage monitoring without external components.

FAQ

What is the exact reset threshold voltage of MAX6328UR23 and how tightly is it specified?

The MAX6328UR23 has a factory-trimmed reset threshold of 2.32V with ±1.5% tolerance at +25°C and ±2.5% over -40°C to +85°C. This value is laser-trimmed during production and verified per Maxim's datasheet Table 1; the "R23" suffix explicitly denotes the 2.32V variant within the MAX6328 family. The MAX6328UR23 achieves this accuracy without external calibration components.

Does MAX6328UR23 support operation at VCC below 2.32V, and what happens to the reset output in that condition?

Yes, MAX6328UR23 remains fully functional down to VCC = 1.0V. When VCC drops below 2.32V, the open-drain RESET output is actively pulled low and held low until VCC rises above 2.32V and remains stable for ≥100ms. Even at VCC = 1.0V, the internal comparator and output driver maintain correct logic state - ensuring fail-safe reset assertion during deep undervoltage events.

Can MAX6328UR23 replace MAX809 in an existing design, and what modifications are needed?

MAX6328UR23 is pin-compatible with MAX809 in SOT23-3 packaging and shares identical pinout (VCC, RESET, GND), but its open-drain RESET output requires an external pull-up resistor - whereas MAX809 uses push-pull. To substitute MAX6328UR23 for MAX809, add a pull-up resistor (typically 10–100kΩ) from RESET to the target logic rail. No PCB layout change is needed beyond this discrete component.

What is the maximum transient duration that MAX6328UR23 ignores at its 2.32V threshold?

At a 200mV overdrive (i.e., VCC = 2.12V), MAX6328UR23 ignores negative transients up to 100µs duration - as shown in Figure MAX6326-04 of the datasheet. This immunity increases as overdrive decreases: at 10mV overdrive (VCC = 2.31V), the maximum allowable glitch width drops to ~10µs. This behavior is inherent to the comparator's internal hysteresis and response time.

Is MAX6328UR23 available in lead-free packaging, and how is it ordered?

Yes, MAX6328UR23 is available in lead-free packaging. To order the RoHS-compliant version, replace the standard "-T" suffix with "+T" - resulting in part number MAX6328UR23+T. Both versions use the same SOT23-3 package and share identical electrical specifications; the "+T" designation confirms matte-tin lead finish and compliance with JEDEC J-STD-020 moisture sensitivity level 1.