Analog Devices Inc./Maxim Integrated MAX6865UK26D2S+T

Overview

The MAX6865UK26D2S+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 2.625V reset threshold (suffix "26"), 40ms minimum reset timeout (suffix "D2"), and integrated watchdog timer with 3.3s typical timeout (suffix "S"). 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 MAX6865UK26D2S+T datasheet, MAX6865UK26D2S+T pinout, MAX6865UK26D2S+T application, or MAX6865UK26D2S+T equivalent, this page delivers verified specifications, validated pin functions, confirmed reset timing behavior, and real-world substitution guidance - all grounded in Maxim's official datasheet Rev 4 (12/2005) and ordering documentation.

Technical Context

The MAX6865UK26D2S+T implements a dual-trigger reset architecture: it asserts reset when VCC falls below 2.625V (±2.5%), when MR is pulled low, or when the watchdog input (WDI) remains static beyond 3.3s (typ). Its internal timer guarantees reset remains asserted for ≥40ms after VCC recovers and MR deasserts.

It uses BiCMOS process technology (2848 transistors), operates from 1.2V to 5.5V, and maintains guaranteed reset validity down to VCC = +1.1V. The WDI input detects edges ≥150ns wide and clears the watchdog timer on any rising or falling transition - enabling robust software supervision without requiring precise pulse symmetry.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SOT-23 packages.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK26D2S+T, MAX6864UK26D2S+T offers identical supervision timing but inverted reset polarity, while TPS3836K26DBVR trades off 9× higher supply current and no watchdog for broader temperature qualification and TI's long-term supply assurance.

Availability

MAX6865UK26D2S+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, wireless hearing aids, and industrial handheld scanners requiring stable component supply across multi-year production cycles.

Supply support for MAX6865UK26D2S+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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX6854–MAX6869 family was designed specifically for ultra-low-power microprocessor supervision in battery-constrained portable medical and consumer electronics - emphasizing nanoscale current draw, guaranteed low-VCC operation, and integrated watchdog reliability.

FAQ

What is the exact reset threshold voltage of the MAX6865UK26D2S+T?

The MAX6865UK26D2S+T has a factory-trimmed reset threshold voltage of 2.625V, with ±2.5% tolerance over temperature (−40°C to +85°C). This value is defined by the "26" suffix per Maxim's Threshold Suffix Guide (Table 2), and is confirmed in the Electrical Characteristics table under VTH parameter. The device asserts reset when VCC falls below this threshold and holds reset for ≥40ms after VCC rises above it.

Does the MAX6865UK26D2S+T require external components for basic operation?

No, the MAX6865UK26D2S+T requires no external components for core functionality: its MR input includes a 10kΩ internal pullup to VCC, the watchdog timer is fully self-contained, and the push-pull active-high RESET output drives directly into most µP reset inputs. A 0.1µF ceramic bypass capacitor on VCC to GND is recommended for noise immunity but is not strictly required for functional operation per datasheet Figure 1 and Pin Description section.

How does the watchdog timer in the MAX6865UK26D2S+T clear and time out?

The MAX6865UK26D2S+T watchdog timer clears on any rising or falling edge at the WDI pin (minimum pulse width 150ns) and times out after 3.3s (typical) if WDI remains static - i.e., held continuously high or low. Timeout triggers a reset pulse lasting ≥40ms. The timer is also cleared when RESET is asserted or MR is pulled low. This edge-triggered behavior avoids false timeouts caused by software delays between toggle instructions.

What is the supply voltage range and minimum operating VCC for valid reset assertion in the MAX6865UK26D2S+T?

The MAX6865UK26D2S+T operates from VCC = 1.2V to 5.5V and guarantees valid RESET assertion down to VCC = +1.1V - meaning the output remains logically correct and capable of driving a load even as the supply sags near depletion. This is explicitly specified in the Electrical Characteristics table and Detailed Description section, ensuring reliable brownout protection in deeply discharged battery scenarios.

Is the MAX6865UK26D2S+T pin-compatible with other devices in the MAX68xx family?

Yes, the MAX6865UK26D2S+T shares the same 5-pin SOT23 package and pinout (VCC, WDI, MR, GND, RESET) with MAX6864/MAX6866/MAX6867–MAX6869 variants. However, pin compatibility does not imply functional equivalence: MAX6865UK26D2S+T provides active-high push-pull RESET, whereas MAX6864 offers active-low and MAX6866 offers open-drain - direct substitution requires verification of reset polarity and load drive requirements.