Analog Devices Inc./Maxim Integrated MAX6864UK26D3L+T

Overview

The MAX6864UK26D3L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, integrating voltage monitoring (2.625V factory-trimmed reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout). It asserts an active-low push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, with guaranteed reset validity down to VCC = +1.1V. It is designed for ultra-low-power portable medical and consumer devices requiring reliable power-on reset and firmware crash recovery.

For engineers reviewing the MAX6864UK26D3L+T datasheet, MAX6864UK26D3L+T pinout, MAX6864UK26D3L+T application, or MAX6864UK26D3L+T equivalent, key selection criteria include its 170nA typical supply current, 2.625V ±2.5% reset threshold, 300ms minimum reset timeout (D3), 209s watchdog period (L suffix), and SOT23-5 footprint compatibility with TPS383x series.

Technical Context

The MAX6864UK26D3L+T implements a dual-monitoring architecture: a precision bandgap-based voltage detector triggers reset when VCC falls below 2.625V (±2.5%), and a digital watchdog timer monitors WDI transitions - resetting if no edge occurs within 209s (typ). Its internal 10kΩ MR pullup and glitch rejection (200ns) enable robust manual reset without external components.

Reset assertion is latched and held for ≥300ms after VCC exceeds threshold and MR deasserts, or after watchdog expiration. The push-pull RESET output drives low to ≤0.3V at 1.2mA sink (VCC ≥ 2.38V), ensuring clean logic-level signaling to µP reset inputs without external pullups.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, 2.9mm × 1.6mm × 1.1mm, lead-free (RoHS-compliant), thermal pad not present.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3836K33DBVR and MAX6361KA26D3+T, the MAX6864UK26D3L+T uniquely integrates both precise voltage monitoring and a 209s watchdog in a single 170nA package - eliminating two discrete components while enabling autonomous firmware crash recovery in battery-critical applications.

Availability

MAX6864UK26D3L+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered wearables, industrial handhelds, and low-power consumer electronics requiring stable component supply across extended production lifecycles.

Supply support for MAX6864UK26D3L+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 markets.

The MAX68xx family delivers nanopower supervisory functions targeting battery-operated equipment where ultra-low ICC, guaranteed reset validity at low VCC, and integrated watchdog capability are essential for safety-critical operation.

FAQ

What is the exact reset threshold voltage of the MAX6864UK26D3L+T?

The MAX6864UK26D3L+T has a factory-trimmed reset threshold of 2.625V 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 "26" corresponds to 2.625V nominal. The threshold remains stable across temperature, with normalized variation ≤±0.5% from -40°C to +85°C per typical characteristics graph.

Does the MAX6864UK26D3L+T require external components for basic operation?

No, the MAX6864UK26D3L+T operates autonomously with zero external components required. It includes an internal 10kΩ pullup on MR, precision voltage reference, watchdog oscillator, and push-pull RESET driver. Only a 0.1µF ceramic bypass capacitor on VCC to GND is recommended for noise immunity - not mandatory for functionality but critical for transient rejection.

How does the watchdog timer in the MAX6864UK26D3L+T clear and expire?

The MAX6864UK26D3L+T watchdog timer clears on any rising or falling edge at WDI, on MR assertion, or during RESET assertion. It expires only if WDI remains static (high or low) for ≥209s (typical), triggering a full reset pulse for 300ms. The timer is disabled while RESET is asserted and resumes counting immediately upon RESET deassertion.

What is the minimum VCC voltage at which the MAX6864UK26D3L+T guarantees valid RESET output?

The MAX6864UK26D3L+T guarantees valid RESET output down to VCC = +1.1V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Below this voltage, RESET behavior is not characterized; above it, VOL ≤0.3V is ensured at 1.2mA sink (VCC ≥ 2.38V), and VOH ≥0.8×VCC is maintained for deasserted state.

Is the MAX6864UK26D3L+T pin-compatible with other MAX68xx supervisory ICs?

The MAX6864UK26D3L+T uses the standard 5-pin SOT23-5 footprint shared across MAX6854–MAX6869, but pin function differs by variant. Specifically, Pin 1 is RESET (push-pull active-low), Pin 3 is MR, and Pin 4 is WDI - matching only MAX6864/MAX6865/MAX6866. It is not pin-compatible with MAX6861–MAX6863 (CT on Pin 1) or MAX6867–MAX6869 (WDI on Pin 1).