Analog Devices Inc./Maxim Integrated MAX6328UR29

Overview

MAX6328UR29 from Maxim Integrated is an ultra-low-power open-drain microprocessor supervisory circuit designed to monitor VCC supply voltage and assert an active-low reset signal when voltage falls below 2.93V. It guarantees correct operation down to 1V supply, delivers ≥100ms reset timeout after power-up, consumes ≤1µA supply current at 3V, and is housed in a 3-pin SOT23 package for space-constrained embedded systems.

For engineers reviewing the MAX6328UR29 datasheet, MAX6328UR29 pinout, MAX6328UR29 application, or MAX6328UR29 equivalent, this device serves as a precision brownout detector with factory-trimmed threshold, transient immunity, and compatibility with bidirectional µP reset pins-key considerations for portable, industrial, and battery-powered designs requiring reliable power-on reset behavior.

Technical Context

The MAX6328UR29 implements a precision bandgap-based reset comparator with ±1.5% (25°C) and ±2.5% (–40°C to +85°C) threshold accuracy over temperature, 40ppm/°C tempco, and built-in hysteresis of 6.3mV to prevent chatter during threshold crossing. Its open-drain RESET output supports flexible pull-up configurations and interfaces directly with µPs like the Motorola 68HC11.

It features immunity to fast VCC transients (up to 100V/µs slew rate), operates across 1.2V–5.5V supply range, and maintains functional reset assertion even as VCC drops to 1V-enabling robust low-voltage brownout detection without external components or trimming.

Key Specifications

Pinout & Package

MAX6328UR29 is packaged in a 3-pin SOT23-3 surface-mount package with 1.3mm × 2.9mm footprint and 0.95mm height, optimized for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809SUR29 and TPS3808G33DBVR, the MAX6328UR29 uniquely balances ultra-low 1µA supply current, factory-trimmed 2.93V threshold, open-drain flexibility, and 100ms reset timeout-making it optimal for space- and power-constrained designs needing interoperability with bidirectional µP reset pins.

Availability

MAX6328UR29 is available at Aetrix Electronics and suitable for industrial PLCs, battery-powered data loggers, medical wearables, and smart meter communication modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for MAX6328UR29 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 analog, mixed-signal, and power management ICs for industrial, communications, and consumer applications.

The MAX6328UR29 belongs to Maxim's ultra-low-power µP supervisory family, engineered specifically for reliable reset generation in battery-operated and space-constrained embedded systems where precision threshold, minimal current draw, and open-drain flexibility are essential.

FAQ

What is the exact reset threshold voltage of MAX6328UR29 and how tightly is it specified?

The MAX6328UR29 has a factory-trimmed reset threshold of 2.93V with ±1.5% tolerance at +25°C and ±2.5% over the full –40°C to +85°C operating range. This specification is guaranteed by production testing-not just design simulation-and ensures consistent brownout detection across temperature and unit-to-unit variation without external calibration. The MAX6328UR29 achieves this using laser-trimmed on-chip resistors during wafer sort.

Does MAX6328UR29 require an external pull-up resistor on its RESET pin?

Yes, the MAX6328UR29 features an open-drain RESET output and therefore requires an external pull-up resistor to define the logic-high voltage level and sink current during reset assertion. Typical values range from 10kΩ to 100kΩ depending on bus capacitance and µP input leakage. This design enables wired-OR configurations and direct interfacing with bidirectional reset pins, such as those found on the Motorola 68HC11-a capability not supported by push-pull alternatives like the MAX6326UR29.

What is the minimum supply voltage at which MAX6328UR29 continues to assert RESET?

The MAX6328UR29 guarantees correct reset assertion down to VCC = 1.0V, meaning it will hold the RESET output low even as the supply decays below the 2.93V threshold and continues falling. This behavior is verified across temperature and ensures fail-safe operation during deep brownout or battery depletion scenarios. Unlike many supervisors that release reset prematurely below 1.8V, the MAX6328UR29 maintains functional integrity to 1V, making it suitable for ultra-low-voltage applications.

How does MAX6328UR29 handle fast transients on the VCC supply line?

The MAX6328UR29 incorporates internal filtering and comparator hysteresis (6.3mV) to reject fast VCC transients, with a specified maximum input slew rate immunity of 100V/µs. Its reset comparator is designed to ignore short-duration negative-going glitches-verified via the "Maximum Transient Duration vs. Reset Threshold Overdrive" curve in the datasheet. This prevents spurious resets during switching noise, capacitor charging events, or ESD-induced supply disturbances, enhancing system reliability in electrically noisy environments.

Is MAX6328UR29 pin-compatible with legacy Maxim reset ICs like MAX809?

No, MAX6328UR29 is not pin-compatible with MAX809 series devices. While both use SOT23-3 packages and share identical pin numbering (VCC, RESET, GND), the MAX809 has a push-pull output and different internal logic-its RESET pin sources current when inactive, whereas MAX6328UR29's open-drain RESET sinks current only when asserted. Swapping them without modifying the pull-up network and µP interface logic will cause functional failure. The MAX6328UR29 is pin-compatible only with other MAX632x/634x SOT23 variants sharing the same open-drain output architecture.