Analog Devices Inc./Maxim Integrated MAX6402BS29+

Overview

MAX6402BS29+ from Maxim Integrated is an ultra-low-power microprocessor supervisory circuit with open-drain active-low reset output, factory-trimmed 2.93V reset threshold (±2.5% over –40°C to +85°C), 100ms minimum reset timeout, and 500nA typical supply current at 3.0V - designed for reliable power-on/brownout detection in space-constrained portable systems.

For engineers reviewing the MAX6402BS29+ datasheet, MAX6402BS29+ pinout, MAX6402BS29+ application, or MAX6402BS29+ equivalent, key selection criteria include its open-drain RESET output for bidirectional µP reset pin interfacing, guaranteed reset validity down to VCC = 1.0V, immunity to sub-200ns VCC transients, and UCSP-4 package compatibility with high-density PCB layouts.

Technical Context

The MAX6402BS29+ integrates a precision bandgap reference comparator and internal reset timer to assert RESET low when VCC falls below 2.93V, holding it low for ≥100ms after VCC rises above threshold. Its open-drain output requires an external pullup and supports wired-OR configurations with microcontrollers having bidirectional reset pins.

It features a manual reset input (MR) with internal 50kΩ pullup, 1µs minimum MR pulse width, and 100ns glitch rejection. The device operates across VCC = 1.2V to 5.5V and guarantees correct logic state down to VCC = 1.0V, with reset delay (tRD) of 20µs and threshold hysteresis of 6.3mV.

Key Specifications

Pinout & Package

MAX6402BS29+ is housed in a 4-bump, 2mm × 2mm UCSP (Ultra-Compact Silicon Package) with bottom-side solder bumps - optimized for minimal PCB footprint and thermal performance in ultra-thin portable designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3808G33DBVR and ADM6315-29ARTZ-RL, the MAX6402BS29+ delivers the lowest quiescent current (500nA vs. >1.2µA), native MR integration in UCSP-4, and guaranteed 1.0V reset validity - making it optimal for long-life, space-constrained, and robustly reset-critical portable systems.

Availability

MAX6402BS29+ is available at Aetrix Electronics and suitable for wearable health monitors, Bluetooth LE peripherals, and portable medical diagnostic tools requiring stable component supply, long-term lifecycle support, and consistent UCSP-4 packaging.

Supply support for MAX6402BS29+ 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and consumer applications.

The MAX6400–MAX6405 family was designed specifically for ultra-low-power, space-constrained microprocessor supervision - targeting battery-powered portable equipment where supply current, footprint, and reset reliability are critical.

FAQ

What is the exact reset threshold voltage of the MAX6402BS29+ and how tightly is it specified?

The MAX6402BS29+ has a factory-trimmed nominal reset threshold of 2.93V, with a tolerance of ±2.5% over the full industrial temperature range (–40°C to +85°C). At +25°C, the threshold is 2.93V ±1.5%, and the device includes 6.3mV of built-in hysteresis to prevent oscillation near the trip point. This precision eliminates the need for external resistor dividers or calibration in most applications.

Does the MAX6402BS29+ require an external pullup resistor on the RESET pin, and why?

Yes, the MAX6402BS29+ requires an external pullup resistor on the RESET pin because it uses an open-drain output configuration. The internal transistor can only pull RESET low; it cannot actively drive high. A pullup resistor (typically 10kΩ to VCC) ensures a defined logic-high level when reset is inactive, enabling wired-OR capability with other reset sources such as microcontroller outputs or FPGA logic - a key feature for systems with bidirectional reset pins.

Can the MAX6402BS29+ operate reliably at VCC voltages below 2.0V, and what happens to reset functionality?

Yes, the MAX6402BS29+ is guaranteed to maintain correct reset output logic state down to VCC = 1.0V. When VCC drops below 2.93V, RESET is asserted low and remains low until VCC rises above threshold and the internal 100ms timer expires. Even at VCC = 1.2V, the device draws only ~1.0µA and continues to monitor and respond - making it suitable for deep brownout recovery in energy-harvesting or end-of-battery-life scenarios.

How does the manual reset (MR) input behave on the MAX6402BS29+, and what is its default state?

The MR input on the MAX6402BS29+ is active-low and features an internal 50kΩ pullup resistor to VCC, so it defaults to logic high when left unconnected. Driving MR low for ≥1µs initiates a reset pulse that holds RESET low for the full 100ms timeout period, even after MR returns high. This allows simple momentary switch implementation (MR to GND) without external biasing or debouncing circuitry - a verified design used in production MP3 players and PDAs.

What package type is used for the MAX6402BS29+, and what are its key mechanical characteristics?

The MAX6402BS29+ uses a 4-bump UCSP (Ultra-Compact Silicon Package) measuring 2.0mm × 2.0mm with bottom-side solder bumps. It has no leads or wire bonds - the silicon die connects directly to the PCB via solder joints. This package is 70% smaller than SC70 and requires careful attention to PCB pad design, solder paste volume, and reflow profile per Maxim's UCSP Reliability Notice, but delivers superior thermal performance and minimal board area usage in ultra-thin portable designs.