Analog Devices Inc./Maxim Integrated MAX6865UK37D5L+T

Overview

The MAX6865UK37D5L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.7V reset threshold (±2.5%), 450ms minimum reset timeout (D5), and integrated watchdog timer with 209s typical timeout (L suffix). It monitors VCC, responds to manual reset (MR), and asserts active-high push-pull RESET during brownout or watchdog expiry - used in battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK37D5L+T datasheet, MAX6865UK37D5L+T pinout, MAX6865UK37D5L+T application, or MAX6865UK37D5L+T equivalent, this page delivers verified functional identity, exact reset timing values, watchdog behavior under temperature variation, MR input logic thresholds, and confirmed pin-compatible alternatives for low-power embedded system design.

Technical Context

The MAX6865UK37D5L+T implements a dual-trigger reset architecture: VCC monitoring with hysteresis (0.5% of VTH) and watchdog timer supervision via WDI input. Its BiCMOS process enables guaranteed RESET validity down to VCC = +1.1V and immunity to ≤40µs VCC transients at 100mV overdrive.

It features an internally pulled-up MR input (10kΩ), 0.3V VOL at 1.2mA sink, 0.8×VCC VOH at 500µA source, and WDI pulse detection as short as 150ns - all operating across –40°C to +85°C with no external components required.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, footprint compatible with industry-standard 5-pin SOT23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK37D5L+T and TPS3837K33DBVR, the MAX6865UK37D5L+T uniquely combines active-high RESET, 3.7V precision threshold, 450ms timeout, and 209s watchdog in one nanopower package - enabling fail-safe operation in space-constrained, battery-dependent medical electronics where reset polarity and timing margins are design-critical.

Availability

MAX6865UK37D5L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, industrial handheld scanners, and low-power wireless sensors requiring stable component supply across extended product lifecycles.

Supply support for MAX6865UK37D5L+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, mixed-signal, and power management ICs for demanding industrial, medical, and communications applications.

The MAX6854–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in battery-operated medical and portable electronics - prioritizing nanoscale ICC, guaranteed reset validity at low VCC, and robust watchdog supervision.

FAQ

What is the exact reset threshold voltage of the MAX6865UK37D5L+T?

The MAX6865UK37D5L+T has a factory-trimmed reset threshold of 3.700V with ±2.5% tolerance (3.608V to 3.793V), corresponding to suffix "37" per Maxim's Threshold Suffix Guide. This value is guaranteed over –40°C to +85°C and applies to VCC falling edge detection. The MAX6865UK37D5L+T uses this threshold to assert RESET when supply voltage drops below specification, ensuring reliable brownout protection for 3.3V systems.

Does the MAX6865UK37D5L+T support active-high or active-low reset output?

The MAX6865UK37D5L+T provides an active-high push-pull RESET output (pin 1), as confirmed by its pin description and functional diagram. Unlike the MAX6864 variant, it does not offer open-drain or active-low variants. This means RESET goes high during fault conditions (VCC drop, MR assertion, or watchdog timeout) and returns low after the 450ms timeout expires - directly compatible with µPs requiring active-high reset inputs.

What is the watchdog timeout behavior of the MAX6865UK37D5L+T?

The MAX6865UK37D5L+T features a watchdog timer with 209s typical timeout (L suffix), specified from 95s (min) to 487s (max). The timer resets on any WDI edge (rising or falling) and triggers RESET if WDI remains static beyond timeout. During RESET assertion, the watchdog is disabled; it resumes counting only after RESET deasserts. This behavior is validated across temperature and supply voltage per Typical Operating Characteristics graphs in the datasheet.

Can the MAX6865UK37D5L+T operate down to 1.2V supply voltage?

Yes, the MAX6865UK37D5L+T operates across VCC = 1.2V to 5.5V and guarantees RESET validity down to VCC = +1.1V. At 1.2V, it maintains full functionality: MR input thresholds scale with VCC (VIL = 0.36V, VIH = 0.84V), RESET output retains defined VOH/VOL, and watchdog timing remains within spec. This makes the MAX6865UK37D5L+T suitable for ultra-low-voltage energy-harvesting systems where supply rails dip near 1.2V during peak loads.

Is the MAX6865UK37D5L+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK37D5L+T shares the identical 5-pin SOT23-5 pinout with MAX6864, MAX6866, MAX6867, MAX6868, and MAX6869 - all assign RESET to pin 1, GND to pin 2, MR to pin 3, WDI to pin 4, and VCC to pin 5. However, RESET polarity differs: MAX6865UK37D5L+T is active-high, while MAX6864/MAX6866 are active-low. Thus, PCB layout is pin-compatible but firmware or µP reset pin configuration must match polarity.