Analog Devices Inc./Maxim Integrated MAX6865UK33D3L+T

Overview

The MAX6865UK33D3L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, a factory-trimmed 3.3V reset threshold (±2.5%), 300ms minimum reset timeout, and integrated watchdog timer with 209s typical timeout. It monitors VCC, responds to manual reset (MR), and triggers reset on watchdog expiration - designed for battery-critical applications like glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK33D3L+T datasheet, MAX6865UK33D3L+T pinout, MAX6865UK33D3L+T application, or MAX6865UK33D3L+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), push-pull active-high RESET output, and compatibility with noisy low-power systems requiring reliable brownout and software fault recovery.

Technical Context

This device integrates three core functions: precision voltage monitoring with hysteresis (0.5% of VTH), a manual reset input with 250ns MR-to-reset delay and internal 10kΩ pullup, and a watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 209s (typ). Its BiCMOS process enables stable operation across -40°C to +85°C with no external components required.

The MAX6865UK33D3L+T uses a fixed 3.3V reset threshold (suffix "33"), D3 reset timeout (150–300ms min/typ/max), and L-suffix watchdog (95–487s min/max, 209s typ). Unlike MAX6861–MAX6863, it lacks CT pin selectability; unlike MAX6854/MAX6855, it includes both MR and WDI inputs and asserts reset on any of three conditions: VCC drop, MR assertion, or watchdog timeout.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK33D3S+T and TPS3837K33DBVR, the MAX6865UK33D3L+T uniquely balances ultra-low power (170nA), long watchdog coverage (209s), and precise 3.3V supervision - making it optimal for battery-constrained medical and industrial IoT endpoints where extended fault detection and multi-year runtime are mandatory.

Availability

MAX6865UK33D3L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, industrial handheld scanners, and smart energy meters requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK33D3L+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 power, sensing, and interface applications in industrial, medical, and communications markets.

The MAX6865UK33D3L+T belongs to Maxim's nanopower µP supervisory family, engineered specifically for ultra-low-power, battery-operated systems demanding reliable voltage monitoring, manual reset, and long-interval watchdog protection without external components.

FAQ

What is the exact reset threshold voltage of the MAX6865UK33D3L+T?

The MAX6865UK33D3L+T has a factory-trimmed reset threshold of 3.3V with ±2.5% tolerance (3.2175V to 3.3825V), confirmed in the Threshold Suffix Guide (suffix "33") and Electrical Characteristics table. This value is guaranteed over -40°C to +85°C and applies to VCC falling conditions. The MAX6865UK33D3L+T does not require external resistor dividers to set this threshold.

Does the MAX6865UK33D3L+T support active-high or active-low reset output?

The MAX6865UK33D3L+T features a push-pull active-high RESET output (pin 1), as specified in the MAX6865 pin description and Selector Guide. When asserted, RESET drives high; when deasserted, it drives low. This eliminates need for external pullup resistors and directly interfaces with µPs requiring active-high reset signals. The MAX6865UK33D3L+T does not offer open-drain or active-low variants.

What is the watchdog timeout behavior of the MAX6865UK33D3L+T?

The MAX6865UK33D3L+T implements an L-suffix watchdog timer with a typical timeout of 209s (min 95s, max 487s), triggered when the WDI input remains static (high or low) beyond that interval. The timer clears on any WDI edge - rising or falling - and is disabled while RESET is asserted. This behavior is documented in Table 3 and the Watchdog Input section of the datasheet for the MAX6865UK33D3L+T.

Can the MAX6865UK33D3L+T operate down to 1.2V supply voltage?

Yes, the MAX6865UK33D3L+T operates across VCC = 1.2V to 5.5V per Absolute Maximum Ratings and Electrical Characteristics. Crucially, its RESET output remains valid and functional down to VCC = +1.1V - ensuring supervision integrity during deep brownout conditions where other supervisors may release reset prematurely. This specification is explicitly guaranteed for the MAX6865UK33D3L+T.

Is the MAX6865UK33D3L+T pin-compatible with other SOT23-5 supervisors?

The MAX6865UK33D3L+T uses standard SOT23-5 pinout (pin 1=RESET, pin 2=GND, pin 3=MR, pin 4=WDI, pin 5=VCC), matching the MAX6864–MAX6866 family. It is not pin-compatible with MAX6854/MAX6855 (no WDI) or MAX6861–MAX6863 (CT instead of WDI). Direct replacement requires verifying WDI functionality and RESET polarity - the MAX6865UK33D3L+T is not a drop-in for non-watchdog or active-low variants.