Analog Devices Inc./Maxim Integrated MAX6302CUA

Overview

MAX6302CUA from Maxim Integrated is an active-high, open-drain microprocessor supervisory circuit in 8-pin µMAX® package, providing adjustable reset threshold (≥1.22V), adjustable reset timeout (2.8–5.2ms with 1500pF), and adjustable watchdog timeout (2.8–5.2ms normal / 1.4–2.6s extended mode). It delivers 4µA supply current and supports VCC = 1.31V to 5.5V, used for reliable power-on reset and hang detection in portable medical instruments.

For engineers reviewing the MAX6302CUA datasheet, MAX6302CUA pinout, MAX6302CUA application, or MAX6302CUA equivalent, key selection considerations include its active-high open-drain RESET output, 500× watchdog extension via WDS pin, transient-immune reset assertion down to VCC = 1.31V, and compatibility with low-leakage ceramic timing capacitors on SRT/SWT pins.

Technical Context

The MAX6302CUA implements a precision bandgap reference (1.22V) feeding a comparator that monitors RESET IN voltage via external resistor divider. Its reset timeout and watchdog timer rely on 500nA precision current sources at SRT and SWT pins, requiring low-leakage (<10nA) capacitors for accurate timing.

Watchdog operation supports two modes: normal (WDS = GND, tWD = 2.67 × CSWT in µs) and extended (WDS = VCC, tWD × 500), with internal WDI pulsing enabling watchdog disable without external drive. The open-drain RESET output interfaces directly with bidirectional µP reset pins and requires external pull-up.

Key Specifications

Pinout & Package

Package: 8-pin µMAX® (U8-1), 3mm × 3mm, 0.5mm pitch, RoHS-compliant, thermal pad optional.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6304CUA, MAX6302CUA offers lower system BOM count (no pull-up needed for MAX6304) but requires external biasing; versus TPS3808G01DBVR, MAX6302CUA trades fixed-threshold simplicity for full adjustability and watchdog flexibility essential in programmable embedded systems.

Availability

MAX6302CUA is available at Aetrix Electronics and suitable for portable medical instruments, industrial handheld scanners, and smart energy meters requiring stable component supply across extended production lifecycles.

Supply support for MAX6302CUA 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 demanding industrial, medical, and communications applications.

The MAX6301–MAX6304 family was engineered specifically for ultra-low-power microprocessor supervision in battery-constrained and transient-prone environments, emphasizing adjustable timing, wide supply range, and robust reset assertion.

FAQ

What is the minimum VCC required for guaranteed operation of the MAX6302CUA?

The MAX6302CUA guarantees functional operation and valid RESET output down to VCC = 1.31V. Below this voltage, reset assertion is not assured. This specification enables reliable use with single-cell lithium batteries discharging to 1.3V, and is confirmed in the Electrical Characteristics table under "Operating Voltage Range" for MAX6302/MAX6304 variants. The MAX6302CUA remains fully specified across its entire 1.31V–5.5V range.

How do I configure the MAX6302CUA for a 100ms watchdog timeout in extended mode?

To achieve ~100ms watchdog timeout in extended mode, connect CSWT = 200pF between SWT and GND, since tWD (extended) ≈ 500 × 2.67 × CSWT (pF) → 100,000µs. Confirm with the "EXTENDED-MODE WATCHDOG TIMEOUT PERIOD vs. CSWT" graph (Figure MAX6301-4 toc02), which shows 200pF yields ~100ms at VCC = 5V. Use X7R or C0G ceramic capacitor with <10nA leakage to maintain accuracy.

Can the MAX6302CUA monitor a 2.5V supply rail, and how is the reset threshold set?

Yes, the MAX6302CUA can monitor a 2.5V rail. Set the reset threshold using external resistors: VRST = 1.22 × (R1 + R2)/R2. For 2.5V, choose R2 = 1MΩ and solve R1 = R2 × (VRST/1.22 − 1) ≈ 1.06MΩ. Connect RESET IN to the divider midpoint. Ensure resistor tolerance ≤1% and layout avoids leakage paths, as RESET IN draws only ±1nA, making it sensitive to contamination.

What is the purpose of the WDS pin on the MAX6302CUA, and how should it be connected?

The WDS pin selects watchdog mode: GND enables normal timeout (tWD = 2.67 × CSWT), VCC enables extended timeout (tWD × 500). It is edge-triggered - a rising edge resets the watchdog timer. In wake-up timer applications, the µP drives WDS high before sleep to enter extended mode, then pulls it low upon wake to resume hang detection. Do not float WDS; tie explicitly to GND or VCC.

Does the MAX6302CUA require external components beyond timing capacitors and resistors?

Yes - the MAX6302CUA requires a 0.1µF ceramic bypass capacitor on VCC (placed adjacent to the pin), external resistor divider on RESET IN, and timing capacitors on SRT and SWT. Additionally, an external pull-up resistor (typically 10–100kΩ) is mandatory on the open-drain RESET output to establish the high state. No other passive or active components are required for basic reset/watchdog functionality.