Analog Devices Inc./Maxim Integrated MAX6303CSA+

Overview

The MAX6303CSA+ from Maxim Integrated is a low-power, +5V microprocessor supervisory circuit with adjustable reset threshold (≥1.22V), adjustable reset timeout (via external capacitor on SRT), and adjustable watchdog timeout (via SWT, extendable 500× via WDS). It features push-pull active-low RESET output, guaranteed assertion down to VCC = 1V, and 4µA supply current - used in battery-powered medical instruments and embedded controllers for reliable brownout and hang detection.

For engineers reviewing the MAX6303CSA+ datasheet, MAX6303CSA+ pinout, MAX6303CSA+ application, or MAX6303CSA+ equivalent, key selection criteria include its push-pull active-low reset output, 4µA quiescent current, guaranteed reset assertion at VCC ≥ 1V, and dual-mode watchdog (normal/extended) with capacitor-based timing.

Technical Context

The MAX6303CSA+ implements a precision bandgap reference (1.22V) feeding a comparator that monitors RESET IN voltage via external resistor divider. Its reset timeout is generated by a 500nA current source charging CSRT, while watchdog timing uses an identical current source on CSWT, with mode selection (normal vs. 500× extended) controlled by WDS logic level.

RESET output is push-pull active-low, sourcing up to VCC − 0.4V (at VCC ≥ 4.5V, ISOURCE = 0.8mA) and sinking ≤ 0.4V (at VCC ≥ 4.5V, ISINK = 3.2mA). The device guarantees valid reset assertion during power-up when VCC reaches 1V and maintains immunity to transients ≤ 50µs at 100mV overdrive.

Key Specifications

Pinout & Package

Package: 8-pin SO (Small Outline), RoHS-compliant, lead-free (indicated by '+' suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6303CSA+, MAX6303CUA+ offers identical functionality in a smaller package but lower power dissipation margin, while TPS3808G01DBVR trades adjustability and watchdog flexibility for lower current and fixed threshold - making it suitable only for non-critical, cost-sensitive designs.

Availability

MAX6303CSA+ is available at Aetrix Electronics and suitable for medical instrumentation, portable diagnostic devices, and industrial embedded controllers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX6303CSA+ 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, and interface applications - emphasizing reliability, low power, and integration.

The MAX6301–MAX6304 family was engineered specifically for microprocessor supervision in battery-powered and noise-prone systems, delivering adjustable reset/watchdog timing with sub-µA quiescent current and robust transient immunity.

FAQ

What is the minimum supply voltage at which MAX6303CSA+ guarantees RESET assertion?

The MAX6303CSA+ guarantees RESET is asserted (low) when VCC reaches or exceeds 1V. This ensures the microprocessor remains held in reset during deep brownout conditions until sufficient supply voltage is restored - a critical feature for data retention and safe startup in battery-powered systems. Below 1V, reset behavior is not guaranteed, though external pulldown resistors can maintain validity down to 0V.

How do I configure the MAX6303CSA+ for a 4.5V reset threshold?

To set a 4.5V reset threshold on the MAX6303CSA+, use the formula VRST = 1.22 × (R1 + R2)/R2. Select R2 = 1MΩ (standard high-value resistor), then solve for R1: R1 = R2 × (VRST/1.22 − 1) ≈ 1MΩ × (4.5/1.22 − 1) ≈ 2.69MΩ. Use a standard 2.7MΩ resistor. Ensure both resistors have low temperature coefficient and minimal leakage to preserve accuracy.

Can the watchdog function of MAX6303CSA+ be disabled entirely?

Yes - in extended mode (WDS = VCC), the watchdog function of MAX6303CSA+ can be disabled by leaving WDI unconnected or driving it with a three-stated output. In this configuration, the internal watchdog driver pulses WDI high near timeout to auto-clear the timer. In normal mode (WDS = GND), WDI cannot be disabled and must be actively toggled; leaving it floating will cause unpredictable resets.

What capacitor value gives a 100ms reset timeout on MAX6303CSA+?

For a 100ms reset timeout, use the formula CSRT = tRP / 2.67, where tRP is in microseconds. Convert 100ms = 100,000µs → CSRT = 100,000 / 2.67 ≈ 37,450pF (37.5nF). Use a low-leakage ceramic capacitor (X7R or C0G) rated ≥16V - leakage <10nA is mandatory to prevent timing drift due to the 500nA SRT current source.

Does MAX6303CSA+ support monitoring voltages other than VCC?

Yes - the MAX6303CSA+ monitors any DC voltage applied to the RESET IN pin, not just VCC. To supervise a 3.3V rail, connect the rail to RESET IN through the same resistor divider used for threshold setting. The device's high-impedance input (±0.01nA leakage) ensures minimal loading, and the 1.22V internal reference remains unchanged - enabling accurate undervoltage detection on auxiliary supplies, battery feeds, or isolated domains.