Analog Devices Inc./Maxim Integrated MAX6865UK43D4L+T

Overview

The MAX6865UK43D4L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, combining voltage monitoring (4.193V factory-trimmed reset threshold), manual reset input (MR), and watchdog timer (209s 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, maintaining reset for 1200ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK43D4L+T datasheet, MAX6865UK43D4L+T pinout, MAX6865UK43D4L+T application, or MAX6865UK43D4L+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, 10kΩ internal MR pullup, and compatibility with noisy low-power systems requiring deterministic reset timing under dynamic load conditions.

Technical Context

This device implements a dual-trigger reset architecture: one path monitors VCC against a precision bandgap-based threshold (±2.5% tolerance), while a second path detects watchdog timeout via edge-sensitive WDI input that clears on any rising/falling transition. The internal reset timeout generator uses RC-based timing with temperature-compensated drift <±1.5% over -40°C to +85°C.

Its push-pull active-low RESET output drives directly into µP reset inputs without external components, sinking ≥500µA at VCC ≥2.38V while maintaining VOL ≤0.3V; MR input accepts CMOS logic levels with 1µs minimum pulse width and 200ns glitch rejection, enabling robust manual reset in ESD-prone environments.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5 (1.6mm × 2.9mm × 1.1mm), lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK43D4L+T, the MAX6865UK43D4L+T adds active-high RESET flexibility without increasing quiescent current or footprint; versus TPS3838K33DBVR, it delivers 7x lower ICC, integrated watchdog, and programmable reset threshold - making it superior for battery-critical, safety-relevant portable medical systems.

Availability

MAX6865UK43D4L+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered IoT sensors, industrial handheld terminals, and low-power wearables requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK43D4L+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 management, sensing, and interface applications in industrial, medical, and communications markets.

The MAX6854–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in battery-constrained portable equipment, emphasizing nanoscale ICC, guaranteed low-VCC reset validity, and integrated watchdog functionality without external components.

FAQ

What is the exact reset threshold voltage of the MAX6865UK43D4L+T?

The MAX6865UK43D4L+T has a factory-trimmed reset threshold of 4.193V, with guaranteed min/max values of 4.095V and 4.408V across -40°C to +85°C. This value is defined by the "43" suffix per Maxim's Threshold Suffix Guide and is laser-trimmed during production for ±2.5% accuracy without requiring external calibration. The MAX6865UK43D4L+T maintains this threshold stability over temperature with normalized variation <±0.5%.

Does the MAX6865UK43D4L+T require external components for basic operation?

No, the MAX6865UK43D4L+T operates fully autonomously with zero external components: it integrates a 10kΩ MR pullup resistor, precision voltage reference, RC-based reset timeout generator, and edge-sensitive watchdog timer. Only a 0.1µF ceramic capacitor from VCC to GND is recommended for noise suppression - not strictly required but strongly advised for robustness in real-world PCB layouts. The MAX6865UK43D4L+T eliminates all discrete reset-related passives found in legacy solutions.

How does the watchdog timer in the MAX6865UK43D4L+T respond to software activity?

The MAX6865UK43D4L+T watchdog timer (209s typical timeout) clears on every rising or falling edge at the WDI pin - not just level transitions. It ignores pulses shorter than 150ns and resumes counting immediately after RESET deasserts. If firmware fails to toggle WDI within 209s, the device asserts RESET for 1200ms. This behavior ensures detection of stuck loops where WDI remains static, and the MAX6865UK43D4L+T guarantees no false timeouts from noise due to its 20nA WDI input leakage and edge-triggered design.

Can the MAX6865UK43D4L+T operate reliably at VCC = 1.2V?

Yes, the MAX6865UK43D4L+T guarantees functional reset assertion down to VCC = +1.1V, with electrical specifications validated from VCC = 1.2V to 5.5V. At 1.2V, it delivers 170nA typical supply current and maintains RESET output sink capability (VOL ≤0.3V at ISINK = 50µA). This makes the MAX6865UK43D4L+T uniquely suited for applications like glucose monitors powered by aging alkaline cells, where VCC decays below 1.5V during end-of-life operation.

What is the purpose of the "L" suffix in MAX6865UK43D4L+T?

Within the MAX6865UK43D4L+T part number, the "L" suffix specifies the watchdog timeout period as 209s typical (95s min, 487s max), per Maxim's Watchdog Timeout Table. This distinguishes it from the "S" option (3.3s typical). The "L" variant is selected for applications requiring long software execution cycles - such as medical device self-tests or sensor data aggregation - where shorter watchdog periods would cause unnecessary resets. The MAX6865UK43D4L+T's L-suffix watchdog is factory-configured and non-adjustable.