Analog Devices Inc./Maxim Integrated MAX6303CUA+

Overview

The MAX6303CUA+ from Maxim Integrated is an adjustable low-power microprocessor supervisory circuit with active-low push-pull reset output, 4µA supply current, 1.22V internal reference, and configurable reset/watchdog timeout via external capacitors. It guarantees RESET assertion down to VCC = 1V and supports power-supply transient immunity - used in battery-powered embedded controllers requiring reliable brownout detection and watchdog supervision.

For engineers reviewing the MAX6303CUA+ datasheet, MAX6303CUA+ pinout, MAX6303CUA+ application, or MAX6303CUA+ equivalent, this page delivers verified functional identity, precise µMAX-8 package mapping, confirmed reset threshold adjustability (≥1.22V), validated watchdog timeout scaling (500×), and real-world design implications for reset timing, WDI/WDS control logic, and VCC < 1V behavior.

Technical Context

The MAX6303CUA+ implements a precision bandgap-based 1.22V reference to set the reset threshold via external resistor divider on RESET IN. Its reset timeout (tRP) and watchdog timeout (tWD) are independently controlled by capacitor values on SRT and SWT pins, each sourcing a stable 500nA current for linear timing.

Watchdog operation features dual-mode selection: normal mode (WDS = GND) yields millisecond-scale timeouts (e.g., 4ms with 1500pF), while extended mode (WDS = VCC) multiplies tWD by 500 - enabling up to ~22-minute supervision without software intervention. The push-pull RESET output drives high after timeout deassertion, eliminating external pull-up requirements.

Key Specifications

Pinout & Package

Package: 8-pin µMAX (U8-1), 3mm × 3mm, exposed pad, RoHS-compliant lead-free.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6303CUA+, MAX6304CUA+ offers identical functionality except reset polarity, enabling drop-in replacement in active-high systems; TPS3808G125DBVR trades adjustability for lower quiescent current and smaller footprint but cannot replace MAX6303CUA+ in watchdog-dependent or brownout-tuned applications.

Availability

MAX6303CUA+ is available at Aetrix Electronics and suitable for medical portable monitors, battery-powered data loggers, industrial PLC I/O modules, and set-top box power sequencing 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) designs precision analog and mixed-signal ICs for power, sensing, interface, and reliability-critical applications.

The MAX6301–MAX6304 family was engineered specifically for ultra-low-power microprocessor supervision in battery-operated and noise-prone systems, emphasizing adjustable thresholds, scalable watchdog timing, and robust reset assertion across wide VCC ranges - with MAX6303CUA+ delivering the active-low push-pull variant in space-constrained µMAX packaging.

FAQ

What is the function of the WDS pin on the MAX6303CUA+?

The WDS pin on the MAX6303CUA+ selects watchdog timer mode: logic-low (GND) enables normal mode with millisecond-scale timeout; logic-high (VCC) activates extended mode, multiplying the basic timeout by 500×. A transition on WDS also clears and restarts the watchdog timer. This dual-mode capability allows one MAX6303CUA+ to serve both fast-firmware-check and deep-sleep-wake-up roles without hardware change.

Can the MAX6303CUA+ monitor voltages other than VCC?

Yes, the MAX6303CUA+ can monitor any DC voltage via the RESET IN pin. Connect the target rail (e.g., 1.8V, 2.5V, or analog sensor supply) to a resistor divider network referenced to ground, sized so the midpoint equals the desired reset threshold (VRST = 1.22 × (R1 + R2)/R2). The MAX6303CUA+'s high-impedance input draws <1nA, minimizing loading - making it suitable for monitoring low-current auxiliary supplies without affecting regulation.

How does the MAX6303CUA+ ensure reliable reset during power-up and brownout?

The MAX6303CUA+ guarantees RESET assertion whenever VCC falls to or below 1V, and its internal 1.22V reference remains stable across temperature. During power-up, RESET stays low until VCC exceeds the programmed VRST and the SRT-configured timeout expires. During brownout, the comparator detects voltage drop below VRST and reasserts RESET for the full tRP period. Its 20mV hysteresis and transient immunity (rejecting ≤50µs glitches ≥100mV deep) prevent chatter during noisy supply transitions.

What capacitor types are recommended for SRT and SWT on the MAX6303CUA+?

Ceramic capacitors are strongly recommended for both SRT and SWT on the MAX6303CUA+ due to their low leakage (<10nA), minimal dielectric absorption, and stability over temperature. Avoid electrolytic or tantalum types, which exhibit higher leakage and voltage coefficient errors that distort timing. For a 4ms reset timeout, use CSRT = 1500pF ±5% X7R ceramic placed within 2mm of the MAX6303CUA+ pin with short, isolated traces to prevent stray coupling.

Is the MAX6303CUA+ pin-compatible with other members of the MAX6301–MAX6304 family?

Yes, the MAX6303CUA+ is fully pin-compatible with MAX6301CUA+, MAX6302CUA+, and MAX6304CUA+ in the 8-pin µMAX package - sharing identical pinout, electrical characteristics, and timing behavior. The only functional differences are reset polarity (active-low vs. active-high) and output structure (open-drain vs. push-pull), defined by part number. This allows direct substitution in layout when changing reset logic requirements, provided firmware and schematic logic levels are updated accordingly.