Analog Devices Inc./Maxim Integrated MAX6865UK41D4L+T

Overview

The MAX6865UK41D4L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 4.1V reset threshold (±2.5%), 1200ms minimum reset timeout, manual reset input (MR), and watchdog timer with 209s typical timeout (L-suffix). It asserts an active-low push-pull RESET output during VCC brownout, MR assertion, or watchdog expiration - used in battery-powered medical monitors and portable instrumentation.

For engineers reviewing the MAX6865UK41D4L+T datasheet, MAX6865UK41D4L+T pinout, MAX6865UK41D4L+T application, or MAX6865UK41D4L+T equivalent, this page delivers verified electrical parameters, exact pin functions, real-world use cases, and validated alternative parts for low-power µP reset and watchdog supervision.

Technical Context

This device integrates three core supervision functions: precision voltage monitoring with hysteresis (0.5% of VTH), a glitch-immune 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). The reset output remains asserted for ≥1200ms after VCC rises above 4.1V and MR deasserts.

Designed for systems requiring guaranteed reset validity down to VCC = +1.1V, it operates across -40°C to +85°C with supply voltage range 1.2V–5.5V. Its BiCMOS process enables nanoscale leakage control, and the SOT23-5 package supports high-density PCB layouts in space-constrained portable designs.

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 TPS3836K33DBVR and MAX6361KA29D3+T, the MAX6865UK41D4L+T uniquely combines 4.1V precision reset, 1200ms timeout, and 209s watchdog in a 170nA package - making it the sole option for long-cycle, battery-critical medical devices requiring both voltage and firmware supervision.

Availability

MAX6865UK41D4L+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered instrumentation, and industrial wireless sensor nodes requiring stable component supply across extended product lifecycles.

Supply support for MAX6865UK41D4L+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 connectivity in demanding industrial and medical applications.

The MAX68xx family delivers nanopower supervision for battery-critical systems - specifically engineered to extend runtime while ensuring robust reset and watchdog behavior in portable healthcare and instrumentation.

FAQ

What is the exact reset threshold voltage of the MAX6865UK41D4L+T?

The MAX6865UK41D4L+T has a factory-trimmed reset threshold of 4.100V ±2.5%, corresponding to the "41" suffix in its part number. This value is guaranteed over -40°C to +85°C and ensures reliable supervision of 4.1V rails without external calibration. The MAX6865UK41D4L+T maintains this accuracy via on-chip trimming and hysteresis of 0.5% of VTH.

Does the MAX6865UK41D4L+T require external components for basic operation?

No, the MAX6865UK41D4L+T operates autonomously with no external components required. A 0.1µF bypass capacitor on VCC is recommended for noise immunity but not mandatory for functionality. The MR input includes a 10kΩ internal pullup, and the push-pull RESET output needs no external pullup - enabling minimal BOM count in space-constrained designs using the MAX6865UK41D4L+T.

How does the watchdog timer in the MAX6865UK41D4L+T respond to software activity?

The MAX6865UK41D4L+T watchdog timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static for ≥209s (typ). This allows flexible software integration - toggling WDI once per main loop or setting/clearing it at strategic points ensures timeout only during true hangs. The MAX6865UK41D4L+T's edge-triggered design prevents false clears during debug halts or slow clock domains.

What is the minimum VCC level at which the MAX6865UK41D4L+T guarantees valid RESET output?

The MAX6865UK41D4L+T guarantees valid RESET output down to VCC = +1.1V, as specified in its absolute maximum and operating characteristics. Below this, RESET may become indeterminate. For applications requiring validity to 0V, a 2MΩ pulldown resistor between RESET and GND is recommended - applicable only to push-pull variants like the MAX6865UK41D4L+T, not open-drain versions.

Is the MAX6865UK41D4L+T pin-compatible with other supervisory ICs?

The MAX6865UK41D4L+T uses a standard 5-pin SOT23-5 footprint and shares pinout compatibility with the TPS3836/TPS3837/TPS3838 series for push-pull active-low variants. However, it is not pin-compatible with open-drain or active-high RESET variants, nor with devices lacking WDI (e.g., MAX6361). Always verify pin function mapping - the MAX6865UK41D4L+T assigns Pin 4 to WDI, unlike non-watchdog parts.