Analog Devices Inc./Maxim Integrated MAX6303CUA

Overview

MAX6303CUA from Maxim Integrated is an active-low, push-pull µP supervisory circuit designed for precise reset and watchdog monitoring in low-power embedded systems. It features adjustable reset threshold (≥1.22V), adjustable reset timeout (2.8–5.2 ms with 1500pF), 4µA supply current, guaranteed RESET assertion down to VCC = 1V, and immunity to power-supply transients. It is used in battery-powered medical instruments and portable controllers requiring reliable brownout detection.

For engineers reviewing the MAX6303CUA datasheet, MAX6303CUA pinout, MAX6303CUA application, or MAX6303CUA equivalent, key selection considerations include its push-pull active-low reset output, µMAX-8 package footprint, 4µA quiescent current, adjustable timing via external capacitors on SRT/SWT, and compatibility with 1.31V–5.5V VCC operation.

Technical Context

The MAX6303CUA implements a precision bandgap-based reset comparator with 1.22V internal reference, enabling externally adjustable reset thresholds via resistor dividers on RESET IN. Its reset timeout and watchdog timeout are independently set using precision 500nA current sources at SRT and SWT pins, driving external capacitors.

Watchdog operation supports two modes: normal (WDS = GND) with µs-range timeout, and extended mode (WDS = VCC) multiplying timeout by 500× (e.g., 1.4–2.6 s with 1500pF). The WDI input detects ≥30ns transitions, and the watchdog timer clears on reset assertion, WDI edge, or WDS state change.

Key Specifications

Pinout & Package

MAX6303CUA is housed in an 8-pin µMAX® package (3mm × 3mm, 0.5mm pitch), RoHS-compliant and lead-free capable. Pinout matches industry-standard SO-8 and PDIP-8 footprints for layout flexibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6301CUA, MAX6303CUA eliminates external pull-up needs and improves noise margin; compared with MAX6304CUA, it maintains compatibility with standard active-low µP reset inputs while retaining identical low-power and timing performance.

Availability

MAX6303CUA is available at Aetrix Electronics and suitable for medical equipment, battery-powered data loggers, and industrial handheld controllers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX6303CUA 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 semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, medical, and communications applications.

The MAX6301–MAX6304 family was designed specifically for low-power, adjustable supervisory functions in space-constrained embedded systems - emphasizing ultra-low ICC, flexible reset/watchdog timing, and robust operation across wide VCC ranges.

FAQ

What is the minimum operating voltage for MAX6303CUA?

The MAX6303CUA operates over a VCC range of 1.31V to 5.5V. Its reset function is guaranteed to assert correctly down to VCC = 1V, making it suitable for deeply discharged battery scenarios. Below 1.31V, timing accuracy degrades but basic reset assertion remains functional per datasheet Note 1.

How do I configure the reset threshold voltage for MAX6303CUA?

Connect a resistor divider between VCC and GND, with the center tap to RESET IN (Pin 1). Use VRST = 1.22 × (R1 + R2)/R2, where R2 is typically 1MΩ and R1 is calculated for the desired threshold. For example, to set VRST = 3.0V, R1 ≈ 1.45MΩ. Ensure resistors are low-leakage and traces are short to avoid threshold errors.

Does MAX6303CUA support watchdog disable functionality?

Yes - the watchdog can be disabled in extended mode (WDS = VCC) by leaving WDI unconnected or three-stating its driver. In this case, the internal watchdog counter pulses WDI low-high-low near timeout to auto-clear. In normal mode (WDS = GND), WDI must be actively toggled; it cannot be disabled.

What capacitor values are recommended for SRT and SWT on MAX6303CUA?

For SRT: use low-leakage ceramic capacitors (≤10nA leakage) with value CSRT = tRP / 2.67 (tRP in µs → CSRT in pF). For 4ms timeout, CSRT = 1500pF. For SWT: same formula applies - CSWT = tWD / 2.67. Avoid electrolytic or high-leakage dielectrics, as they cause timing drift.

Is MAX6303CUA pin-compatible with other devices in the MAX6301–MAX6304 family?

Yes - all MAX6301–MAX6304 variants share identical 8-pin µMAX, SO, and PDIP pinouts and electrical interfaces. Only the RESET output polarity (active-low vs. active-high) and drive type (open-drain vs. push-pull) differ. Hardware layout is fully interchangeable; only firmware or schematic netlist changes may be needed for output polarity.