Analog Devices Inc./Maxim Integrated MAX6865UK28D5L+T

Overview

The MAX6865UK28D5L+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 (timeout = 209s typ) with ultra-low 170nA typical supply current. It asserts an active-high push-pull RESET signal during VCC brownout, MR assertion, or watchdog timeout, and holds reset for 450ms min after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK28D5L+T datasheet, MAX6865UK28D5L+T pinout, MAX6865UK28D5L+T application, or MAX6865UK28D5L+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), pin-selectable reset output type, and lead-free SOT23-5 packaging compatible with high-density PCB layouts.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over -40°C to +85°C, coupled with a digital watchdog timer that clears on any WDI edge (rising or falling) and expires if WDI remains static beyond 209s (typ). The internal reset timeout generator uses a temperature-stable RC oscillator calibrated to deliver 450ms minimum assertion time (D5 option) after VCC recovery or MR release.

The MAX6865UK28D5L+T features a dedicated active-high push-pull RESET output referenced to VCC, an internally 10kΩ-pulled-up MR input tolerant of CMOS logic levels, and a WDI input with 150ns pulse-width detection capability. Its BiCMOS process enables guaranteed operation from VCC = 1.2V to 5.5V while maintaining sub-µA quiescent current across the full temperature range.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, 2.9mm × 1.6mm footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK28D5L+T, the MAX6864UK28D5S+T offers identical supervision architecture but trades long watchdog coverage for faster response, while the TPS3836K33DBVR sacrifices both watchdog capability and nanopower efficiency for broader vendor availability in non-critical applications.

Availability

MAX6865UK28D5L+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered instrumentation, and industrial handheld equipment requiring stable component supply with guaranteed long-term lifecycle support.

Supply support for MAX6865UK28D5L+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) designs precision analog and mixed-signal ICs for demanding industrial, medical, and communications applications, with emphasis on power efficiency and reliability.

The MAX6865UK28D5L+T belongs to the MAX68xx nanopower supervisory family, engineered specifically for ultra-low-power, safety-critical portable electronics where extended battery life and deterministic reset behavior are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6865UK28D5L+T?

The MAX6865UK28D5L+T has a factory-trimmed reset threshold of +2.800V, with ±2.5% tolerance over the full -40°C to +85°C operating temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "28" corresponds to 2.800V nominal. The device guarantees valid reset assertion down to VCC = +1.1V, making it suitable for systems experiencing deep brownout conditions.

Does the MAX6865UK28D5L+T require external components for basic operation?

No, the MAX6865UK28D5L+T operates autonomously with no external components required. It integrates an internal 10kΩ pullup on the MR pin, a precision voltage reference, RC-based reset timeout generator, and edge-sensitive watchdog timer. Only a 0.1µF ceramic bypass capacitor between VCC and GND is recommended for noise immunity - this is standard practice for all linear regulators and supervisors, not a functional requirement unique to the MAX6865UK28D5L+T.

What does the "L" suffix in MAX6865UK28D5L+T indicate?

The "L" suffix in MAX6865UK28D5L+T specifies the watchdog timeout period: 209s typical (95s min, 487s max), per Table 3 ("Watchdog Timeout") in the datasheet. This distinguishes it from the "S" suffix (3.3s typical), enabling robust firmware supervision in applications with long processing cycles, such as clinical data logging or infrequent sensor polling - critical for reliable operation in MAX6865UK28D5L+T-based medical devices.

How is the reset timeout period determined for the MAX6865UK28D5L+T?

The reset timeout period for the MAX6865UK28D5L+T is fixed at 450ms minimum (D5 option), as defined in Table 4 ("Reset Timeout Periods") of the datasheet. Unlike the MAX6861–MAX6863 variants, the MAX6865UK28D5L+T does not feature a CT pin for dynamic timeout selection - its D5 timeout is factory-programmed and unchangeable. This ensures predictable reset hold time for µP initialization without runtime configuration overhead.

Is the MAX6865UK28D5L+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK28D5L+T shares the same 5-pin SOT23-5 package and pinout (RESET, GND, MR, WDI, VCC) with MAX6864/MAX6866 variants, but is not pin-compatible with MAX6854–MAX6856 (no WDI) or MAX6861–MAX6863 (CT pin instead of WDI). Pin compatibility is strictly limited to the MAX6864/MAX6865/MAX6866 subgroup - swapping with non-WDI or CT-equipped variants would cause functional failure due to missing or misassigned signals.