Analog Devices Inc./Maxim Integrated MAX6865UK38D5S+T

Overview

MAX6865UK38D5S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.800V reset threshold (±2.5%), 300ms minimum reset timeout, and integrated watchdog timer with 3.3s typical timeout. It monitors VCC, responds to manual reset (MR), and asserts active-high push-pull RESET during brownout, power-up, or watchdog expiry - used in battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK38D5S+T datasheet, MAX6865UK38D5S+T pinout, MAX6865UK38D5S+T application, or MAX6865UK38D5S+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, MR glitch rejection of 200ns, and compatibility with 1.2V–5.5V supply rails in space-constrained portable systems.

Technical Context

The MAX6865UK38D5S+T implements a voltage-monitoring comparator with 2.5% hysteresis, a digital watchdog timer cleared by WDI edges (min pulse width 150ns), and a fixed 300ms reset timeout after VCC recovery or MR deassertion. Its internal 10kΩ MR pullup and CMOS-compatible WDI/CT inputs enable direct interfacing with µP I/O without external biasing.

Unlike basic supervisors, it combines three independent reset triggers - VCC drop below 3.800V, MR assertion, or WDI stall exceeding 3.3s - all forcing a synchronized active-high RESET output referenced to VCC. The push-pull driver delivers VOH ≥ 0.8×VCC at 500µA source current and VOL ≤ 0.3V at 1.2mA sink current across full temperature range.

Key Specifications

Pinout & Package

MAX6865UK38D5S+T uses a lead-free 5-pin SOT23-5 package (2.9mm × 1.6mm × 1.1mm) with GND on pin 2 and pin 3, enabling robust thermal dissipation and PCB area efficiency in wearable designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3838K33DBVR and STM6315SW33DX, MAX6865UK38D5S+T delivers 10× lower supply current, integrated watchdog for firmware health monitoring, and precise 3.800V threshold matching Li-ion mid-discharge voltage - critical for medical-grade reliability in battery-constrained applications.

Availability

MAX6865UK38D5S+T is available at Aetrix Electronics and suitable for glucose monitoring systems, patient vital sign monitors, industrial handheld scanners, and smart wearable sensors requiring stable component supply with long-term lifecycle support.

Supply support for MAX6865UK38D5S+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 markets.

The MAX6865UK38D5S+T belongs to the MAX68xx nanopower supervisory family, engineered specifically for ultra-low-power, high-reliability monitoring in battery-operated medical and portable electronics where reset accuracy and energy efficiency are critical.

FAQ

What is the exact reset threshold voltage of MAX6865UK38D5S+T?

The MAX6865UK38D5S+T has a factory-trimmed reset threshold of 3.800V 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 "38" corresponds to 3.800V nominal. The device guarantees valid RESET assertion down to VCC = +1.1V, making MAX6865UK38D5S+T suitable for applications monitoring partially discharged lithium-based batteries.

Does MAX6865UK38D5S+T support active-high or active-low reset output?

MAX6865UK38D5S+T provides an active-high push-pull RESET output, as specified in its pin description (pin 1) and Selector Guide. Unlike MAX6864/MAX6866 variants, MAX6865UK38D5S+T asserts RESET high during fault conditions and deasserts it low after timeout. Its VOH ≥ 0.8×VCC at 500µA source current ensures clean logic-level compatibility with modern µP reset inputs requiring active-high signaling.

What watchdog timeout period does the "S" suffix indicate in MAX6865UK38D5S+T?

The "S" suffix in MAX6865UK38D5S+T denotes a typical watchdog timeout period of 3.3 seconds, with min/max values of 1.5s and 7.75s respectively (per Table 3). This timeout is optimized for embedded firmware that performs periodic tasks within several seconds - such as sensor polling or BLE advertising intervals - ensuring MAX6865UK38D5S+T detects hangs without excessive false positives during normal operation.

Can MAX6865UK38D5S+T operate from a 1.8V supply?

Yes, MAX6865UK38D5S+T operates across 1.2V to 5.5V, including 1.8V nominal rails. At VCC = 1.8V, its supply current is 170nA (typ), RESET output VOL ≤ 0.3V at 500µA sink, and VOH ≥ 0.8×VCC (≥1.44V) at 200µA source. This makes MAX6865UK38D5S+T fully compatible with 1.8V I/O domains while maintaining guaranteed reset validity down to VCC = +1.1V.

Is MAX6865UK38D5S+T pin-compatible with other MAX68xx devices?

MAX6865UK38D5S+T shares the same 5-pin SOT23-5 package and pinout (VCC–GND–MR–WDI–RESET) with MAX6864/MAX6866, but differs from MAX6861–MAX6863 (which use CT instead of WDI) and MAX6854–MAX6856 (which lack WDI). Pin compatibility is limited to the MAX6864/MAX6865/MAX6866 subgroup; substitution requires verifying reset polarity, timeout, and threshold match - MAX6865UK38D5S+T is not a drop-in replacement for non-watchdog variants.