Analog Devices Inc./Maxim Integrated MAX6865UK40D2L+T

Overview

The MAX6865UK40D2L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, combining voltage monitoring (4.000V reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with ultra-low 170nA supply current. It asserts an active-high push-pull RESET signal during VCC brownout, MR assertion, or watchdog timeout, and guarantees valid reset operation down to VCC = +1.1V - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK40D2L+T datasheet, MAX6865UK40D2L+T pinout, MAX6865UK40D2L+T application, or MAX6865UK40D2L+T equivalent, this page delivers verified technical context, exact pin functions, real-world timing behavior (tRP = 40ms min, tWD = 209s typ), and validated alternative options for low-power embedded supervision.

Technical Context

The MAX6865UK40D2L+T implements a dual-trigger reset architecture: it monitors VCC against a factory-trimmed 4.000V threshold and independently watches WDI activity. Its watchdog timer clears on any rising or falling edge at WDI and expires only if WDI remains static beyond 209s (typ), making it suitable for firmware recovery in infrequently updated systems.

Reset assertion is synchronized across all triggers - VCC drop, MR low, or watchdog expiry - and deassertion follows a fixed 40ms minimum timeout period after VCC exceeds 4.000V and MR is released. The push-pull active-high RESET output drives directly to VCC without external components and sinks ≤0.3V at 1.2mA load.

Key Specifications

Pinout & Package

MAX6865UK40D2L+T uses a 5-pin SOT23-5 package (2.9mm × 1.6mm × 1.1mm height), lead-free, RoHS-compliant, with standard thermal pad layout per JEDEC MO-178AB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK40D2L+T, MAX6864UK40D2L+T provides identical supervision parameters but requires µP-level reset polarity adaptation, while TPS3838K33DBVR sacrifices watchdog capability and ultra-low current for lower cost in non-critical applications.

Availability

MAX6865UK40D2L+T is available at Aetrix Electronics and suitable for portable medical devices, wireless sensor nodes, industrial handheld terminals, and battery-powered instrumentation requiring stable component supply with full lifecycle support.

Supply support for MAX6865UK40D2L+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, mixed-signal, and power management ICs for demanding industrial, medical, and communications applications.

The MAX68xx family delivers nanopower supervision with integrated watchdog timers for battery-critical systems where reliability and ultra-low quiescent current are mandatory design requirements.

FAQ

What is the exact reset threshold voltage of the MAX6865UK40D2L+T?

The MAX6865UK40D2L+T has a factory-trimmed reset threshold of 4.000V with ±2.5% tolerance over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "40" corresponds to 4.000V nominal. The MAX6865UK40D2L+T maintains this accuracy across temperature and supply variations, enabling precise brownout detection in 3.3V and 5V systems.

Does the MAX6865UK40D2L+T require external components for basic operation?

No, the MAX6865UK40D2L+T operates autonomously with no external components required. Its internal 10kΩ MR pullup, factory-set 4.000V threshold, and fixed 40ms reset timeout eliminate the need for resistors, capacitors, or trimming circuits. A 0.1µF ceramic capacitor from VCC to GND is recommended for noise suppression but is not strictly required for functional operation of the MAX6865UK40D2L+T.

How does the watchdog timer in the MAX6865UK40D2L+T behave during reset assertion?

While RESET is asserted (active-high), the MAX6865UK40D2L+T's watchdog timer is disabled and does not count. It resumes timing only after RESET deasserts. This ensures that watchdog expiration cannot occur during reset hold-off, preventing race conditions. The timer clears on any WDI edge - rising or falling - and expires only after 209s (typ) of static WDI state, as specified by the "L" suffix in MAX6865UK40D2L+T.

Can the MAX6865UK40D2L+T be used with a microprocessor that requires an active-low reset input?

No - the MAX6865UK40D2L+T features an active-high push-pull RESET output and is not compatible with µPs requiring active-low reset without external inversion. For such systems, consider the pin-compatible MAX6864UK40D2L+T (active-low push-pull) or MAX6866UK40D2L+T (active-low open-drain). The MAX6865UK40D2L+T's output logic is fixed and not configurable via pins or registers.

What is the minimum VCC voltage at which the MAX6865UK40D2L+T guarantees valid RESET assertion?

The MAX6865UK40D2L+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". Below this voltage, RESET behavior is not characterized. This specification ensures deterministic reset signaling during deep brownout conditions common in aging lithium batteries, a key requirement for the MAX6865UK40D2L+T's target medical and portable applications.