Analog Devices Inc./Maxim Integrated MAX6865UK18D4L+T

Overview

MAX6865UK18D4L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 1.8V reset threshold (±2.5%), 1200ms minimum reset timeout, manual reset input (MR), and watchdog timer with 209s typical timeout. It monitors VCC in battery-powered medical and portable electronics to ensure reliable µP startup and fault recovery.

For engineers reviewing the MAX6865UK18D4L+T datasheet, MAX6865UK18D4L+T pinout, MAX6865UK18D4L+T application, or MAX6865UK18D4L+T equivalent, key selection criteria include guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), push-pull active-high RESET output, and watchdog input (WDI) pulse detection as short as 150ns.

Technical Context

The MAX6865UK18D4L+T integrates voltage monitoring, manual reset assertion, and watchdog timer functionality in a single BiCMOS IC. Its reset logic asserts RESET high when VCC falls below 1.8V, MR is pulled low, or WDI remains static beyond 209s (typ); RESET remains asserted for ≥1200ms after recovery.

It uses an internal 10kΩ pullup on MR and supports CMOS-level WDI transitions. The watchdog timer clears on any rising/falling edge at WDI, reset assertion, or MR assertion - enabling robust software execution monitoring without external timing components.

Key Specifications

Pinout & Package

MAX6865UK18D4L+T is housed in a lead-free 5-pin SOT23-5 package (JEDEC MO-178AA), 2.9mm × 1.6mm × 1.1mm, with gull-wing leads and thermal pad not connected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK18D4L+T, MAX6864UK18D4S+T offers faster watchdog response but reduced idle tolerance, while TPS3836K33DBVR omits critical safety features (watchdog, MR) and requires PCB layout revision due to non-identical pin mapping.

Availability

MAX6865UK18D4L+T is available at Aetrix Electronics and suitable for glucose monitors, portable ECG sensors, smart inhalers, and other battery-powered medical devices requiring stable component supply with long-term lifecycle support.

Supply support for MAX6865UK18D4L+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 precision analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX68xx family delivers nanopower supervision for ultra-low-power embedded systems, targeting applications where battery longevity, reliability under voltage stress, and integrated watchdog functionality are critical design requirements.

FAQ

What is the reset threshold voltage of MAX6865UK18D4L+T?

The MAX6865UK18D4L+T has a factory-trimmed reset threshold of 1.800V with ±2.5% tolerance (1.755V to 1.845V), specified over -40°C to +85°C. This value is encoded in the "18" suffix per Maxim's Threshold Suffix Guide and ensures precise brownout detection for 1.8V logic rails. The threshold remains stable across temperature, with normalized variation ≤±0.5% from -40°C to +85°C.

Does MAX6865UK18D4L+T support active-high or active-low reset output?

MAX6865UK18D4L+T provides an active-high push-pull RESET output (Pin 1). When VCC drops below 1.8V, MR is pulled low, or the watchdog timer expires, RESET transitions from low to high and remains high for ≥1200ms after recovery. This eliminates external pullup resistors and simplifies interface with µPs requiring high-active reset inputs.

What is the watchdog timeout period for MAX6865UK18D4L+T?

The MAX6865UK18D4L+T features a watchdog timeout period of 209s typical (95s min, 487s max), denoted by the "L" suffix. The timer resets on any rising or falling edge at WDI, and expires only if WDI remains static beyond this interval. This long timeout suits infrequently active firmware, such as dose counters or environmental loggers.

Can MAX6865UK18D4L+T operate down to 1.1V supply voltage?

Yes, MAX6865UK18D4L+T guarantees valid RESET output down to VCC = +1.1V, ensuring deterministic reset behavior during deep brownout conditions. Below 1.1V, RESET may become undefined, but the device continues to monitor VCC and will reassert RESET correctly once VCC recovers above the 1.8V threshold.

Is MAX6865UK18D4L+T pin-compatible with other MAX68xx devices?

MAX6865UK18D4L+T shares the same 5-pin SOT23-5 package and pinout (Pin 1: RESET, Pin 2: GND, Pin 3: MR, Pin 4: WDI, Pin 5: VCC) with MAX6864/MAX6866 variants. However, it is not pin-compatible with MAX6861–MAX6863 (which use CT instead of WDI) or MAX6854–MAX6856 (which lack WDI). Always verify pin function alignment before substitution.