Analog Devices Inc./Maxim Integrated MAX6865UK28D6S+T

Overview

The MAX6865UK28D6S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (reset threshold = +2.800V), manual reset input (MR), and watchdog timer (WDI) with 209s typical timeout. It asserts an active-high push-pull RESET output for ≥600ms after VCC recovery or MR deassertion, and is guaranteed functional down to VCC = +1.1V. It serves as a system-level power-on reset and fault recovery controller in ultra-low-power portable medical and consumer devices.

For engineers reviewing the MAX6865UK28D6S+T datasheet, MAX6865UK28D6S+T pinout, MAX6865UK28D6S+T application, or MAX6865UK28D6S+T equivalent, key selection criteria include its 2.800V factory-trimmed reset threshold, 600–1200ms reset timeout (D6 option), 209s watchdog period (L suffix), active-high push-pull RESET output, and operation at VCC ≥1.1V - all critical for battery-powered systems requiring deterministic brownout recovery and software fault detection.

Technical Context

This device implements a dual-monitoring architecture: a precision bandgap-based voltage detector triggers reset when VCC falls below +2.800V (±2.5%), and a digital watchdog timer monitors WDI transitions to detect firmware hangs. The internal reset timeout generator uses RC-based timing with factory calibration to ensure ±25% accuracy over -40°C to +85°C.

The MR input features 10kΩ internal pullup and 250ns MR-to-reset delay, while the active-high push-pull RESET output delivers VOH ≥0.8×VCC at ISOURCE = 500µA and VOL ≤0.3V at ISINK = 1.2mA. Immunity to VCC transients <40µs (at 100mV overdrive) ensures robust operation in noisy supply environments.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, footprint-compatible with industry-standard 5-pin supervisory ICs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK28D6S+T and TPS3837K28DBVR, the MAX6865UK28D6S+T uniquely delivers integrated watchdog supervision at nanopower levels, enabling robust firmware monitoring in space-constrained, battery-critical medical and industrial edge devices without compromising runtime.

Availability

MAX6865UK28D6S+T is available at Aetrix Electronics and suitable for portable medical diagnostics, battery-powered patient monitors, and low-power IoT asset trackers requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6865UK28D6S+T 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 MAX68xx family was designed specifically for ultra-low-power microprocessor supervision in battery-critical systems, integrating precision voltage monitoring, manual reset, and watchdog functionality into minimal-footprint packages.

FAQ

What is the exact reset threshold voltage of the MAX6865UK28D6S+T?

The MAX6865UK28D6S+T has a factory-trimmed reset threshold of +2.800V, with guaranteed tolerance of ±2.5% over the full operating temperature range (-40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "28" corresponds to 2.800V nominal. The MAX6865UK28D6S+T uses this precise threshold to reliably monitor 2.8V supply rails without external calibration.

Does the MAX6865UK28D6S+T provide watchdog timer functionality, and what is its timeout?

Yes, the MAX6865UK28D6S+T includes a watchdog timer with a typical timeout of 209 seconds, indicated by the "L" suffix in the part number. The watchdog monitors transitions on the WDI pin and triggers reset if no edge is detected within this period. The MAX6865UK28D6S+T's watchdog is edge-triggered and cleared on any rising or falling edge, making it robust against firmware lockups where WDI remains static.

What type of RESET output does the MAX6865UK28D6S+T feature, and how is it configured?

The MAX6865UK28D6S+T provides an active-high push-pull RESET output on Pin 1. This means the output drives high during reset assertion and low when deasserted, eliminating the need for an external pullup resistor. The MAX6865UK28D6S+T's push-pull structure ensures strong drive capability (VOH ≥0.8×VCC at 500µA source current), simplifying interface to modern µPs with active-high reset inputs.

What is the minimum supply voltage at which the MAX6865UK28D6S+T guarantees valid reset operation?

The MAX6865UK28D6S+T guarantees valid reset assertion down to VCC = +1.1V, as explicitly stated in the Electrical Characteristics table under "Guaranteed Reset Valid to VCC = +1.1V". This ensures deterministic behavior during deep brownout conditions where other supervisors may fail. The MAX6865UK28D6S+T maintains this specification across its full -40°C to +85°C temperature range.

How does the MAX6865UK28D6S+T handle short-duration supply transients?

The MAX6865UK28D6S+T is immune to VCC transients ≤40µs in duration when the overdrive is 100mV above the reset threshold, as shown in the "Maximum VCC Transient Duration vs. Reset Threshold Overdrive" graph. This transient rejection prevents false resets caused by switching noise or load dumps. The MAX6865UK28D6S+T achieves this through internal filtering and hysteresis (0.5% of VTH), making it suitable for electrically noisy portable equipment.