Analog Devices Inc./Maxim Integrated MAX6331SUR+

Overview

The MAX6331SUR+ from Maxim Integrated is a precision shunt regulator with integrated active-high reset output in a 3-pin SOT23-3 package. It provides 3.3V regulated shunt voltage (±1.5% tolerance), 140ms reset timeout, and operates over -40°C to +85°C. Designed for microprocessor power monitoring in high-voltage systems, it replaces discrete regulator + reset IC solutions in space-constrained applications like portable instrumentation.

For engineers reviewing the MAX6331SUR+ datasheet, MAX6331SUR+ pinout, MAX6331SUR+ application, or MAX6331SUR+ equivalent, key selection criteria include shunt voltage accuracy (±1.5%), reset threshold stability (±1.5% over temperature), 100µA–50mA shunt current range, and guaranteed active-high RESET assertion during brownout recovery.

Technical Context

The MAX6331SUR+ integrates a precision bandgap-based shunt regulator and a comparator-driven reset generator with internal 140ms timeout timer. Its SHUNT pin regulates at 3.3V with 40ppm/°C tempco, while RESET asserts high only after V_SHUNT exceeds 3.06V and remains above threshold for ≥140ms.

It functions as a two-terminal shunt device requiring external series resistor (R_S) to set input current range, with RESET output sourcing up to 800µA at 0.8×V_SHUNT and sinking capability disabled - confirming its active-high push/pull architecture distinct from open-drain alternatives.

Key Specifications

Pinout & Package

MAX6331SUR+ uses a 3-pin SOT23-3 package with exposed pad (U3+1 land pattern per Maxim outline 21-0151). Pin 1 = GND, Pin 2 = RESET (active-high output), Pin 3 = SHUNT (regulated 3.3V node).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar shunt-regulator-with-reset applications.

Compared with TLV803EC26DBZR and MAX6326UR33+T, the MAX6331SUR+ uniquely combines 3.3V shunt regulation and active-high reset in one SOT23-3 package - eliminating both external reference and pull-up components while maintaining identical 140ms timeout reliability.

Availability

MAX6331SUR+ is available at Aetrix Electronics and suitable for intelligent instruments, critical µP power monitoring, and portable/size-sensitive equipment requiring stable component supply across industrial temperature ranges.

Supply support for MAX6331SUR+ 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 management, sensing, and interface applications.

The MAX6330/MAX6331 family targets cost-sensitive, space-constrained µP supervisory functions - integrating shunt regulation and reset generation to replace multi-component solutions in battery-powered and high-voltage-derived systems.

FAQ

What is the exact shunt voltage and reset threshold of MAX6331SUR+?

The MAX6331SUR+ provides a nominal shunt voltage of 3.3V with ±1.5% tolerance over -40°C to +85°C. Its reset threshold is 3.06V, also with ±1.5% tolerance. These values are confirmed in the Electrical Characteristics table of the official datasheet (Rev 2, 4/14), where MAX6331_T variant specifies V_SHUNT = 3.25V to 3.35V and V_TH = 3.01V to 3.11V at +25°C, and 2.97V to 3.15V across full temperature range.

Does MAX6331SUR+ require an external pull-up resistor on the RESET pin?

No, MAX6331SUR+ does not require an external pull-up resistor. Its RESET pin is an active-high push/pull output capable of sourcing 800µA at 0.8×V_SHUNT, enabling direct connection to microprocessor reset inputs. This differs from open-drain alternatives like TLV803, where a pull-up is mandatory - a key advantage of the MAX6331SUR+ in minimizing external components.

What is the minimum bypass capacitor required for stable operation of MAX6331SUR+?

The minimum bypass capacitor required for stable operation of MAX6331SUR+ is 0.03µF (30nF), as specified in the Applications Information section. This value ensures stability across the full 100µA–50mA shunt current range. Using less than 0.03µF risks oscillation or overshoot during load transients, while larger values (e.g., 0.1µF) improve transient response but increase recovery time.

Can MAX6331SUR+ operate from a 5V input source?

Yes, MAX6331SUR+ can operate from a 5V input source when paired with an appropriately sized series resistor (R_S). The device regulates at 3.3V, so R_S must be selected to ensure shunt current stays within 100µA–50mA across all operating conditions. For example, with 5V input and 0mA load, R_S ≈ (5V – 3.3V)/50mA = 34Ω minimum; derating for tolerance yields ~39Ω standard value.

How does the 140ms reset timeout of MAX6331SUR+ behave during brownout recovery?

During brownout recovery, the MAX6331SUR+ resets its internal 140ms timer whenever V_SHUNT falls below 3.06V. Only after V_SHUNT rises above threshold and remains stable for the full 140ms does RESET go high. This ensures µP reset remains asserted throughout voltage instability - a behavior verified in the Typical Operating Characteristics graph "Power-Up Reset Timeout vs. Temperature" (TOC03) and Detailed Description section.