Analog Devices Inc./Maxim Integrated MAX6401BS28

Overview

MAX6401BS28 from Maxim Integrated is an ultra-low-power microprocessor supervisory circuit with active-high push-pull reset output, factory-trimmed 2.80V threshold (±2.5% over –40°C to +85°C), 100ms minimum reset timeout, and 500nA typical supply current at 3.0V. It monitors VCC down to 1.0V and includes a manual reset input (MR) with internal 50kΩ pullup, used in battery-powered systems requiring reliable power-on/brownout reset signaling.

For engineers reviewing the MAX6401BS28 datasheet, MAX6401BS28 pinout, MAX6401BS28 application, or MAX6401BS28 equivalent, this device serves as a precision voltage-monitoring supervisor for portable electronics where low quiescent current, guaranteed reset validity below 1.2V, and compact UCSP-4 packaging are critical selection criteria.

Technical Context

The MAX6401BS28 implements a precision bandgap reference comparator with factory-trimmed 2.80V reset threshold and ±2.5% accuracy across –40°C to +85°C. Its internal timer asserts RESET high for ≥100ms after VCC rises above VTH, and guarantees valid logic state down to VCC = 1.0V.

It features immunity to fast VCC transients (≤200ns rejection), MR input with 1µs minimum pulse width and 100ns glitch rejection, and operates across 1.2V–5.5V supply range. The active-high push-pull output drives VOH ≥0.8×VCC at 500µA source current and VOL ≤0.4V at 3.2mA sink current.

Key Specifications

Pinout & Package

MAX6401BS28 is housed in a 4-bump, 2mm × 2mm chip-scale package (UCSP-4), optimized for space-constrained portable designs. The package uses solder bumps directly on die for minimal footprint and thermal resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6401BS28, MAX6400BS28 provides identical monitoring accuracy and timing but requires redesign of reset signal polarity handling, while MAX6402BS28 adds board-level component overhead and alters reset bus topology - making MAX6401BS28 optimal for single-supervisor, active-high µP interfaces with minimal footprint.

Availability

MAX6401BS28 is available at Aetrix Electronics and suitable for portable/battery-powered equipment, cell phones, and MP3 players requiring stable component supply, long-lifecycle support, and consistent UCSP-4 packaging.

Supply support for MAX6401BS28 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 precision analog and mixed-signal ICs for power, sensing, and interface applications, with emphasis on high-reliability, low-power solutions.

The MAX6400–MAX6405 family was engineered specifically for ultra-low-power microprocessor supervision in space- and energy-constrained portable electronics, delivering factory-trimmed thresholds and sub-µA operation in chip-scale packaging.

FAQ

What is the exact reset threshold voltage of MAX6401BS28 and how stable is it over temperature?

The MAX6401BS28 has a nominal reset threshold of 2.80V, with ±2.5% accuracy guaranteed over the full –40°C to +85°C operating range. At +25°C, the tolerance is tighter at ±1.5%. This stability ensures reliable brownout detection across environmental extremes without external calibration - a key requirement for battery-powered devices where voltage margins shrink at low temperatures.

Does MAX6401BS28 require external components to function?

No, MAX6401BS28 operates autonomously with no external components required. It integrates a precision bandgap reference, comparator, timer, and 50kΩ MR pullup resistor. Only VCC, GND, MR (optional), and RESET connections are needed - eliminating resistors, capacitors, or trimming circuits typically associated with discrete reset solutions.

Can MAX6401BS28 assert a valid reset signal when VCC drops below 1.2V?

Yes, MAX6401BS28 guarantees correct reset output logic state down to VCC = 1.0V. When VCC falls below 2.80V, RESET goes high and remains high until VCC recovers and sustains ≥100ms above threshold. This behavior is fully specified and tested - critical for preserving system integrity during deep brownout or end-of-battery-life conditions.

What is the maximum load the RESET output of MAX6401BS28 can drive?

The MAX6401BS28 RESET output is a push-pull driver capable of sourcing 500µA while maintaining VOH ≥0.8×VCC, and sinking up to 3.2mA while holding VOL ≤0.4V. This allows direct interface with most µP reset inputs without buffering, including those with internal weak pull-downs or Schmitt-trigger receivers.

Is the UCSP-4 package of MAX6401BS28 compatible with standard reflow processes?

Yes, the UCSP-4 package of MAX6401BS28 is qualified for standard lead-free reflow profiles with peak bump reflow temperature up to +235°C. However, Maxim emphasizes that CSP reliability depends heavily on PCB material, pad design, and assembly process - users must follow Maxim's UCSP application note for solder mask, stencil design, and thermal profile validation to ensure long-term interconnect integrity.