Analog Devices Inc./Maxim Integrated MAX803LEXR

Overview

MAX803LEXR from Maxim Integrated is a 3-pin SC70-packaged microprocessor supervisory circuit with open-drain active-low RESET output, 4.63V ±1.5% reset threshold, 140ms minimum reset timeout, 12µA supply current at +25°C, and guaranteed operation down to VCC = +1V. It monitors +5V power supplies in embedded controllers and portable systems to prevent erroneous code execution during power-up, brownout, or power-down.

For engineers reviewing the MAX803LEXR datasheet, MAX803LEXR pinout, MAX803LEXR application, or MAX803LEXR equivalent, this page delivers verified technical context, package mapping, real-world timing behavior, and validated alternative options for industrial and automotive-grade reset supervision.

Technical Context

The MAX803LEXR implements a precision voltage comparator with 30ppm/°C tempco and built-in hysteresis to detect VCC drops below 4.63V, asserting RESET until VCC rises above threshold and remains stable for ≥140ms. Its open-drain output requires an external pullup resistor and supports level-shifting to voltages up to +6V.

Designed for operation from -40°C to +125°C, the device guarantees valid reset assertion even as VCC decays to +1V, and rejects transients ≤20µs at 100mV overdrive. It draws only 12µA typical supply current and contains no internal capacitors-enabling fully passive, no-component-required integration.

Key Specifications

Pinout & Package

MAX803LEXR is housed in a 3-pin SC70 package (package code X3-2), measuring 1.25mm × 0.85mm × 0.95mm, with gull-wing leads and RoHS-compliant lead-free finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX803LEXR, MAX809LEXR removes external component dependency but sacrifices level-shifting flexibility, while TPS3808G15DBVR offers lower current and programmability at the cost of pin compatibility and full automotive temperature validation.

Availability

MAX803LEXR is available at Aetrix Electronics and suitable for industrial PLC controllers, automotive body control modules, portable medical sensors, smart energy meters, and battery-powered instrumentation requiring stable component supply across extended temperature ranges.

Supply support for MAX803LEXR 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, mixed-signal, and power management ICs for industrial, automotive, communications, and computing applications.

The MAX803 family delivers highly accurate, low-power reset supervision for microprocessors operating from +2.5V to +5V rails, targeting applications where reliability, small size, and guaranteed timing behavior are critical.

FAQ

What is the exact reset threshold voltage of the MAX803LEXR and how tightly is it specified?

The MAX803LEXR has a nominal reset threshold of 4.63V, with a guaranteed tolerance of ±1.5% over the full -40°C to +125°C operating temperature range. This specification ensures precise activation at exactly 5% below a +5V nominal supply, minimizing uncertainty zones where reset might or might not assert during marginal voltage conditions. The threshold is factory-trimmed and characterized per device, not derived from typical values.

Does the MAX803LEXR require an external pullup resistor, and if so, what value is recommended?

Yes, the MAX803LEXR requires an external pullup resistor on its open-drain RESET pin because it cannot drive high actively. A 10kΩ resistor pulled to the monitored +5V rail is standard; values from 4.7kΩ to 100kΩ are acceptable depending on bus capacitance and noise immunity needs. The resistor enables level-shifting to higher voltages (up to +6V) and supports wired-OR reset architectures with multiple supervisors.

Can the MAX803LEXR operate reliably when VCC drops below 1.2V, and what happens to the RESET output?

The MAX803LEXR is guaranteed to assert and maintain a valid low-level RESET signal down to VCC = +1V. Below +1.2V, the internal comparator remains functional, but output sink capability degrades gradually. At VCC < +1V, RESET transitions to high-impedance-so a pullup resistor ensures it remains logically high, avoiding undefined states. This behavior is explicitly tested and documented in the datasheet's "Ensuring a Valid Reset Output Down to VCC = 0V" section.

What is the minimum reset pulse width of the MAX803LEXR, and how does temperature affect it?

The MAX803LEXR guarantees a minimum reset pulse width of 140ms after VCC rises above the 4.63V threshold. Over temperature, the actual timeout varies: it is typically 230ms at +25°C, increases to ~245ms at +85°C, and reaches ~250ms at +125°C (per Figure MAX803-TOC5). This monotonic increase ensures conservative timing margins across the full automotive and industrial temperature range.

How does the MAX803LEXR handle fast VCC transients, and what is its immunity limit?

The MAX803LEXR rejects fast negative-going VCC transients via comparator hysteresis and internal filtering. For a 100mV overdrive (VTH – VCC = 100mV), it ignores transients ≤20µs in duration at +25°C (per Figure MAX803-TOC4). Immunity decreases as overdrive increases-e.g., a 200mV glitch must be <10µs. A 0.1µF ceramic capacitor placed directly at the VCC pin further enhances immunity without requiring additional circuitry.