Analog Devices Inc./Maxim Integrated MAX6865UK18D5L+T

Overview

The MAX6865UK18D5L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, combining voltage monitoring (1.8V reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with ultra-low 170nA supply current. It asserts an active-high push-pull RESET signal during VCC brownout, MR assertion, or watchdog timeout, maintaining reset for 450ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK18D5L+T datasheet, MAX6865UK18D5L+T pinout, MAX6865UK18D5L+T application, or MAX6865UK18D5L+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), pin-selectable reset output type, and lead-free SOT23-5 packaging compliant with industrial temperature range (-40°C to +85°C).

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% reset threshold accuracy and 0.5% hysteresis, coupled with a digitally timed watchdog circuit that clears on any WDI edge and expires if WDI remains static beyond 209s (typ). Its internal 10kΩ MR pullup and glitch rejection (200ns) enable robust manual reset without external components.

The MAX6865UK18D5L+T uses BiCMOS process technology (2848 transistors) to achieve nanoscale quiescent current while maintaining full functionality across 1.2V–5.5V VCC range. Its push-pull active-high RESET output drives directly to VCC with VOH ≥ 0.8×VCC (ISOURCE = 500µA) and VOL ≤ 0.3V (ISINK = 1.2mA), eliminating need for external pullups.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, -40°C to +85°C operating temperature range.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK18D5S+T and TPS3837K18DBVR, the MAX6865UK18D5L+T uniquely combines long-interval watchdog supervision (209s), precise 1.8V brownout detection, and active-high push-pull RESET in a single nanopower device - eliminating secondary supervision ICs in battery-critical medical and industrial designs.

Availability

MAX6865UK18D5L+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered instrumentation, and industrial handheld equipment requiring stable component supply with guaranteed long-term availability and RoHS-compliant lead-free packaging.

Supply support for MAX6865UK18D5L+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 battery-constrained systems, integrating voltage monitoring, manual reset, and configurable watchdog functionality into minimal 5-pin SOT23 packages.

FAQ

What is the exact reset threshold voltage of the MAX6865UK18D5L+T?

The MAX6865UK18D5L+T has a factory-trimmed reset threshold of 1.800V 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 "18" corresponds to 1.755V (min), 1.800V (typ), and 1.845V (max). The threshold is referenced to the VCC pin and remains stable across temperature with <0.5% normalized drift.

Does the MAX6865UK18D5L+T require external components for basic operation?

No, the MAX6865UK18D5L+T operates autonomously with zero external components. It includes an internal 10kΩ pullup on the MR pin, precision voltage reference, and watchdog oscillator. Only a 0.1µF bypass capacitor on VCC is recommended for noise immunity - no resistors, capacitors, or additional ICs are required for voltage monitoring, manual reset, or watchdog functionality.

What does the "L" suffix in MAX6865UK18D5L+T indicate?

The "L" suffix in MAX6865UK18D5L+T specifies the watchdog timeout period: 95s (min), 209s (typ), and 487s (max). This distinguishes it from the "S" suffix (1.5s/3.3s/7.75s). The L-suffix enables supervision of firmware with long idle intervals - such as monthly self-tests in smoke detectors - without risking premature timeout and spurious reset.

How does the MAX6865UK18D5L+T handle VCC transients?

The MAX6865UK18D5L+T is immune to short VCC transients up to 40µs duration when the overdrive is 100mV (i.e., VCC dips 100mV below threshold). This is verified in the "Maximum VCC Transient Duration vs. Reset Threshold Overdrive" graph (Figure MAX684 toc05). Transients shorter than this limit will not trigger a reset, preventing false resets in electrically noisy environments like motor-driven handheld tools.

Is the MAX6865UK18D5L+T pin-compatible with other MAX68xx devices?

The MAX6865UK18D5L+T shares the identical 5-pin SOT23-5 pinout with all MAX6864–MAX6866 variants (pin 1 = RESET, pin 2 = GND, pin 3 = MR, pin 4 = WDI, pin 5 = VCC). However, it is not pin-compatible with MAX6861–MAX6863 (which use CT instead of WDI on pin 4) or MAX6854–MAX6856 (which lack WDI entirely). Always verify pin function mapping per device variant.