Analog Devices Inc./Maxim Integrated MAX6400BS31

Overview

MAX6400BS31 from Maxim Integrated is an ultra-low-power microprocessor supervisory circuit in a 4-bump UCSP package, designed to monitor VCC supply voltage and assert an active-low push-pull reset signal when voltage drops below 3.08V (±2.5% over –40°C to +85°C). It features 500nA typical supply current, factory-set 100ms minimum reset timeout, manual reset input with internal 50kΩ pullup, and guaranteed reset validity down to VCC = 1.0V. Used in battery-powered portable devices requiring reliable power-on reset and brownout protection.

For engineers reviewing the MAX6400BS31 datasheet, MAX6400BS31 pinout, MAX6400BS31 application, or MAX6400BS31 equivalent, key selection criteria include its 3.08V threshold accuracy, UCSP-4 footprint constraints, push-pull active-low output drive capability, and immunity to sub-200ns VCC transients - all critical for space-constrained, low-quiescent-current embedded systems.

Technical Context

The MAX6400BS31 integrates a precision bandgap reference comparator trimmed to 3.08V nominal threshold, with ±2.5% accuracy across –40°C to +85°C and 40ppm/°C tempco. Its internal timer ensures reset remains asserted for ≥100ms after VCC rises above threshold, and it ignores fast VCC transients ≤200ns (at 100mV overdrive).

It supports manual reset via MR pin - a logic-low input that asserts reset for the full timeout period even after release - and guarantees correct output state (RESET low) for VCC as low as 1.0V. The push-pull output drives low to 0.3V at 1.6mA (VCC ≥ 2.1V) and high to ≥0.8×VCC at 500µA source current.

Key Specifications

Pinout & Package

Package: UCSP-4 (4-bump, 2×2 mm chip-scale package), lead-free, RoHS-compliant, tape-and-reel delivery only.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3123E18DBVR and STM6315RBW1F, the MAX6400BS31 delivers the lowest quiescent current (500nA) in the smallest footprint (UCSP-4), making it optimal for ultra-long-life, space-constrained portable designs where reset timing and threshold accuracy are tightly specified.

Availability

MAX6400BS31 is available at Aetrix Electronics and suitable for portable medical sensors, wearable fitness trackers, industrial handheld scanners, and smart remote controls requiring stable component supply and long-term manufacturability.

Supply support for MAX6400BS31 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 battery-operated systems needing precise, self-contained reset supervision without external components.

FAQ

What is the exact reset threshold voltage of the MAX6400BS31 and how stable is it over temperature?

The MAX6400BS31 has a nominal reset threshold of 3.08V, with ±2.5% accuracy guaranteed over the full operating temperature range of –40°C to +85°C. Its temperature coefficient is 40ppm/°C, meaning drift is less than ±12mV across the entire range. This stability ensures consistent brownout detection in portable equipment exposed to ambient temperature swings, and the value is factory-trimmed - no field calibration is needed. The MAX6400BS31 maintains this performance without external components.

Does the MAX6400BS31 require any external components to function as a reset supervisor?

No, the MAX6400BS31 operates as a complete reset solution with no external components required. It integrates a precision bandgap reference, comparator, reset timer, and push-pull output driver. The manual reset (MR) pin includes a 50kΩ internal pullup resistor, so it can be left unconnected if unused. Unlike many supervisors, the MAX6400BS31 eliminates the need for external resistors, capacitors, or pullups - reducing BOM cost and PCB area while improving reliability. This is confirmed in the MAX6400BS31 datasheet's "No External Components" feature.

What is the minimum VCC voltage at which the MAX6400BS31 guarantees correct reset output behavior?

The MAX6400BS31 guarantees correct reset output logic state - specifically, RESET remains low when VCC is below 3.08V - down to VCC = 1.0V. This is explicitly stated in the datasheet's Electrical Characteristics table and Detailed Description section. That capability ensures deterministic reset assertion during deep brownout or ultra-low-voltage wake-up conditions, a critical requirement for battery-powered systems nearing end-of-life. The MAX6400BS31 maintains this guarantee across its full –40°C to +85°C operating range.

How does the manual reset (MR) input behave on the MAX6400BS31, and what are its electrical specifications?

The MR input on the MAX6400BS31 is active-low with an internal 50kΩ pullup to VCC. A logic-low signal (≤0.8V) asserts reset, and RESET remains low for the full 100ms timeout period even after MR returns high. MR accepts TTL- or CMOS-compatible levels and tolerates noise via built-in 100ns glitch rejection. Its minimum pulse width is 1µs, and it draws negligible current due to the internal pullup. This behavior is fully documented in the MAX6400BS31 datasheet's Manual Reset Input section and Electrical Characteristics table.

What package type is used for the MAX6400BS31, and are there any special handling or assembly considerations?

The MAX6400BS31 uses a 4-bump UCSP-4 (2×2 mm chip-scale package), not a traditional leaded package. It requires careful attention to PCB pad layout, solder paste volume, and reflow profile per Maxim's UCSP Reliability Notice. Unlike SOIC or SOT-23, UCSP lacks leads to absorb mechanical stress - solder joint integrity depends heavily on board material, assembly process, and thermal cycling environment. The MAX6400BS31 is supplied in tape-and-reel only, and full qualification was completed per Maxim's published timeline. No leaded alternatives exist for this specific variant.