Analog Devices Inc./Maxim Integrated MAX6865UK38D1S+T

Overview

The MAX6865UK38D1S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (3.705V factory-trimmed reset threshold), manual reset input (MR), and watchdog timer (3.3s typical timeout) with ultra-low 170nA typical supply current. It asserts an active-low push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, and holds reset for 10ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices requiring long shelf life and reliable power-on reset.

For engineers reviewing the MAX6865UK38D1S+T datasheet, MAX6865UK38D1S+T pinout, MAX6865UK38D1S+T application, or MAX6865UK38D1S+T equivalent, key selection criteria include its 3.705V reset threshold, 10ms reset timeout, 3.3s watchdog period, SOT23-5 footprint, and guaranteed RESET validity down to VCC = +1.1V - all critical for low-voltage, low-power embedded systems where supply stability and fail-safe startup are non-negotiable.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over -40°C to +85°C, paired with a digital watchdog timer that clears on any WDI edge (rising or falling) and expires if WDI remains static beyond 3.3s (typ). The internal reset timeout generator uses a temperature-stable RC oscillator, delivering 10ms minimum assertion time with <±10% variation across temperature.

The MR input features 10kΩ internal pullup and 250ns MR-to-reset delay, while the push-pull RESET output drives low to ≤0.3V at 1.2mA sink (VCC ≥ 2.38V) and high to ≥0.8×VCC at 500µA source - enabling direct interface with 1.8V–5.5V µP reset inputs without external level-shifting.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), 2.9mm × 1.6mm footprint, 1.1mm height, thermal pad not present.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK38D1S+T, the MAX6865UK38D1S+T adds no functional difference for this configuration but shares identical pinout and electrical behavior; versus TPS3836K33DBVR, it delivers 7× lower supply current, 3.3s watchdog coverage, and tighter threshold accuracy - making it superior for battery-critical medical wearables.

Availability

MAX6865UK38D1S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered diagnostics equipment, and low-power IoT sensor nodes requiring stable component supply with guaranteed long-term availability and lead-free compliance.

Supply support for MAX6865UK38D1S+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 MAX68xx family was designed specifically for ultra-low-power microprocessor supervision in portable and implantable medical electronics, emphasizing nanoscale current consumption, precise voltage thresholds, and robust watchdog reliability under varying battery conditions.

FAQ

What is the exact reset threshold voltage of the MAX6865UK38D1S+T?

The MAX6865UK38D1S+T has a factory-trimmed reset threshold of 3.705V, with ±2.5% tolerance over -40°C to +85°C. This value is defined by the "38" suffix per Maxim's Threshold Suffix Guide (Table 2), corresponding to a nominal 3.800V with actual min/typ/max of 3.705V/3.800V/3.895V - verified in the Electrical Characteristics table under VTH parameter.

Does the MAX6865UK38D1S+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK38D1S+T includes a watchdog timer with a typical timeout period of 3.3 seconds, indicated by the "S" suffix in the part number. Per Table 3, the S-suffix guarantees a minimum of 1.5s and maximum of 7.75s, making it suitable for firmware loops requiring moderate fault-detection latency without excessive overhead.

What is the reset timeout duration for the MAX6865UK38D1S+T, and how is it selected?

The MAX6865UK38D1S+T has a fixed 10ms minimum reset timeout period, specified by the "D1" suffix. Unlike MAX6861–MAX6863 variants, it does not feature a CT pin for dynamic timeout selection - the D1 option is hardwired internally, ensuring consistent 10ms assertion time after VCC recovery or MR release.

What package type and footprint does the MAX6865UK38D1S+T use?

The MAX6865UK38D1S+T uses a 5-pin SOT23 package (SOT23-5), measuring 2.9mm × 1.6mm with 0.95mm pin pitch. It is lead-free (RoHS-compliant), denoted by the "+T" suffix, and requires standard SOT23 reflow profiles - compatible with automated pick-and-place and reflow soldering in high-volume medical device assembly.

How does the MAX6865UK38D1S+T ensure reliable reset assertion during deep brownout conditions?

The MAX6865UK38D1S+T guarantees valid RESET output down to VCC = +1.1V, as confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables. Its internal voltage reference and reset comparator remain functional at this level, ensuring the µP receives a deterministic low-state reset signal even as the supply collapses - critical for preventing undefined states in safety-critical medical firmware.