Analog Devices Inc./Maxim Integrated MAX6865UK25D3S+T

Overview

The MAX6865UK25D3S+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 2.5V reset threshold (±2.5%), 300ms minimum reset timeout (D3), and integrated watchdog timer with 3.3s typical timeout (S suffix). It monitors VCC, responds to manual reset (MR), and asserts reset on voltage drop, MR assertion, or watchdog expiration - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK25D3S+T datasheet, MAX6865UK25D3S+T pinout, MAX6865UK25D3S+T application, or MAX6865UK25D3S+T equivalent, this page delivers verified technical context, exact pin functions, real-world timing behavior, and validated alternative options for low-power µP reset and watchdog supervision.

Technical Context

The MAX6865UK25D3S+T implements a dual-trigger reset architecture: it asserts reset when VCC falls below 2.5V (±2.5%), when MR is pulled low, or when the watchdog input (WDI) remains static beyond 3.3s (typ). Its internal watchdog timer clears on any WDI edge, MR assertion, or active reset - ensuring robust detection of software hangs.

Reset output is active-low push-pull, guaranteed valid down to VCC = 1.1V, with VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.38V) and VOH ≥ 0.8×VCC at ISOURCE = 500µA. The device requires no external components and operates across –40°C to +85°C.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact footprint (2.9mm × 1.6mm × 1.1mm) suitable for space-constrained portable designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK25D3S+T, MAX6864UK25D3S+T omits active-high reset capability but shares identical supervision parameters, while TPS3836K25DBVR trades 26× higher current for TI's production stability and broader distributor stock - making it viable only where watchdog functionality is excluded.

Availability

MAX6865UK25D3S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered wearables, and low-power IoT endpoints requiring stable component supply across extended product lifecycles.

Supply support for MAX6865UK25D3S+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 systems.

The MAX68xx family delivers nanopower supervisory circuits optimized for battery-critical applications - combining voltage monitoring, manual reset, and watchdog timer in minimal SOT23 footprints without compromising timing accuracy or reliability.

FAQ

What is the exact reset threshold voltage of the MAX6865UK25D3S+T?

The MAX6865UK25D3S+T has a factory-trimmed reset threshold of 2.500V with ±2.5% tolerance over –40°C to +85°C. This value is specified in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "25" corresponds to VTH = 2.5V. The device guarantees valid reset assertion down to VCC = 1.1V, supporting operation through deep brownout conditions.

Does the MAX6865UK25D3S+T include a watchdog timer, and what is its timeout?

Yes, the MAX6865UK25D3S+T includes an integrated watchdog timer with a typical timeout of 3.3 seconds (S suffix), with min/max values of 1.5s and 7.75s. The timer clears on any rising or falling edge at the WDI pin, on MR assertion, or during active reset - ensuring robust detection of firmware hangs without requiring precise pulse timing from the host µP.

What is the reset timeout period for the MAX6865UK25D3S+T, and how is it selected?

The MAX6865UK25D3S+T has a fixed 300ms minimum reset timeout period (D3 suffix), with typical and maximum values of 225ms and 300ms respectively. Unlike the MAX6861–MAX6863 variants, this timeout is factory-set and not user-selectable via external pins - simplifying design for applications requiring consistent, known reset hold time after power recovery or manual reset.

What type of reset output does the MAX6865UK25D3S+T provide?

The MAX6865UK25D3S+T provides an active-low push-pull reset output on Pin 1. This eliminates the need for an external pullup resistor and ensures strong drive capability: VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.38V) and VOH ≥ 0.8×VCC at ISOURCE = 500µA, enabling direct interface to standard µP reset inputs without level-shifting.

Is the MAX6865UK25D3S+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK25D3S+T uses the same 5-pin SOT23-5 package and pinout as MAX6864/MAX6866/MAX6867–MAX6869 variants: Pin 1 = RESET, Pin 2 = GND, Pin 3 = MR, Pin 4 = WDI, Pin 5 = VCC. It is not pin-compatible with MAX6854–MAX6863 (which place WDI or CT on Pin 1 or 4 differently) or with TPS3836-series parts that share the footprint but differ in internal function mapping.