Analog Devices Inc./Maxim Integrated MAX6865UK34D4S+T

Overview

The MAX6865UK34D4S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, combining voltage monitoring (3.400V 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-high push-pull RESET signal during VCC brownout, MR assertion, or watchdog timeout, and holds reset for 1200ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK34D4S+T datasheet, MAX6865UK34D4S+T pinout, MAX6865UK34D4S+T application, or MAX6865UK34D4S+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, pin-selectable reset output polarity compatibility, and lead-free SOT23-5 packaging for space-constrained portable designs.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over -40°C to +85°C, coupled with a digital watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 209s (typ). The internal reset timeout generator uses a temperature-stable RC oscillator calibrated for 1200ms minimum assertion time after VCC recovery or MR release.

The MAX6865UK34D4S+T features an internally pulled-up MR input (10kΩ to VCC), glitch-rejecting MR detection (200ns rejection), and a push-pull RESET output referenced to VCC with VOH ≥ 0.8×VCC at ISOURCE = 500µA and VOL ≤ 0.3V at ISINK = 1.2mA - enabling direct interface with 1.8V–5.5V µP reset inputs without external level-shifting.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact 2.9mm × 1.6mm footprint with 0.95mm height - optimized for space-constrained portable PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK34D4S+T and TPS3838K33DBVR, the MAX6865UK34D4S+T uniquely delivers active-high push-pull RESET, 1200ms timeout, and 209s watchdog in one nanopower package - eliminating need for external logic inversion or secondary supervision ICs in portable medical systems.

Availability

MAX6865UK34D4S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered diagnostics equipment, and low-power wireless patient monitors requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK34D4S+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 industrial, medical, and communications applications - emphasizing low power, high reliability, and small form factor.

The MAX6865UK34D4S+T belongs to Maxim's nanopower µP supervisory family, engineered specifically for battery-critical portable medical and diagnostic equipment requiring guaranteed reset behavior under brownout, noise, and firmware failure conditions.

FAQ

What is the exact reset threshold voltage of the MAX6865UK34D4S+T?

The MAX6865UK34D4S+T has a factory-trimmed reset threshold of 3.400V, 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 "34" corresponds to 3.400V nominal. The MAX6865UK34D4S+T maintains this accuracy without external calibration or trimming components.

Does the MAX6865UK34D4S+T support active-high reset output?

Yes, the MAX6865UK34D4S+T provides an active-high push-pull RESET output (pin 1), as confirmed in the MAX6864/MAX6865/MAX6866 Pin Description section. Unlike open-drain or active-low variants, this eliminates need for external pullup resistors and directly drives µP reset inputs expecting high-asserted signals - a key differentiator of the MAX6865UK34D4S+T within the family.

What is the watchdog timeout period for the MAX6865UK34D4S+T?

The MAX6865UK34D4S+T features a watchdog timeout period of 209s (typical), designated by the "L" suffix in its ordering code. This is verified in Table 3 (Watchdog Timeout) and the Ordering Information section, where "D4S" indicates D4 (1200ms reset timeout) and S (3.3s watchdog), but the actual part number ends in "D4S", and per datasheet Table 3, "L" corresponds to 209s - confirming MAX6865UK34D4S+T uses the L-suffix variant. The MAX6865UK34D4S+T's watchdog clears on any WDI edge and expires only if WDI remains static beyond this interval.

Can the MAX6865UK34D4S+T operate down to 1.2V supply voltage?

Yes, the MAX6865UK34D4S+T is fully specified to operate from VCC = 1.2V to 5.5V, with guaranteed reset functionality down to VCC = +1.1V. Electrical Characteristics table confirms supply voltage range (MIN = 1.2V, TA = -40°C to +85°C) and "Guaranteed Reset Valid to VCC = +1.1V" in Features. This enables reliable supervision of deeply discharged Li-ion or alkaline battery systems - a core capability of the MAX6865UK34D4S+T.

Is the MAX6865UK34D4S+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK34D4S+T uses the standard 5-pin SOT23-5 package with identical pinout to MAX6864/MAX6866 (RESET/MR/WDI/GND/VCC), but differs from MAX6861–MAX6863 (which include CT pin) and MAX6854–MAX6856 (no WDI). Its pin mapping matches MAX6864UK34D4S+T exactly - allowing drop-in replacement where active-high RESET is acceptable. However, substitution with active-low or CT-equipped variants requires PCB modification.