Analog Devices Inc./Maxim Integrated MAX6865UK37D5S+T

Overview

The MAX6865UK37D5S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.7V reset threshold (±2.5%), 300ms minimum reset timeout, and integrated watchdog timer with 3.3s typical timeout. It monitors VCC, responds to manual reset (MR), and triggers reset on watchdog expiration - used in battery-powered medical and portable electronics for reliable power-up/brownout recovery.

For engineers reviewing the MAX6865UK37D5S+T datasheet, MAX6865UK37D5S+T pinout, MAX6865UK37D5S+T application, or MAX6865UK37D5S+T equivalent, key selection criteria include its active-high push-pull RESET output, guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), and compatibility with 1.2V–5.5V supply rails in space-constrained designs.

Technical Context

This device belongs to the MAX6864–MAX6869 family, which integrates voltage monitoring, manual reset input, and a watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 3.3s (typ). Its internal architecture includes a precision bandgap reference, hysteresis-controlled comparator (0.5% VTH), and digital timeout counter with temperature-stable timing.

The MAX6865UK37D5S+T uses a BiCMOS process (2848 transistors) and features an internally pulled-up MR input (10kΩ), noise-immune WDI input (150ns pulse detection), and push-pull active-high RESET referenced to VCC - eliminating need for external pullup while ensuring fast, rail-to-rail output drive under load.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK37D5S+T, the MAX6865UK37D5S+T's active-high RESET simplifies interface to most modern ARM Cortex-M MCUs; versus TPS3837K33DBVR, it adds critical watchdog safety and cuts supply current by 90%, enabling decade-long battery life in medical wearables.

Availability

MAX6865UK37D5S+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 long production lifecycles.

Supply support for MAX6865UK37D5S+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 MAX6864–MAX6869 product line was designed specifically for ultra-low-power microprocessor supervision in battery-critical systems, integrating precision voltage monitoring, manual reset, and edge-triggered watchdog functionality in minimal SOT23 footprints.

FAQ

What is the exact reset threshold voltage of the MAX6865UK37D5S+T?

The MAX6865UK37D5S+T has a factory-trimmed reset threshold of 3.700V with ±2.5% tolerance, meaning the actual VTH falls between 3.608V and 3.793V across temperature and process variation. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "37" corresponds to 3.700V nominal. The device guarantees reset assertion when VCC falls below this threshold and deassertion only after VCC exceeds it plus hysteresis (0.5% of VTH).

Does the MAX6865UK37D5S+T require external components for basic operation?

No, the MAX6865UK37D5S+T operates autonomously with zero external components required. Its MR input includes a 10kΩ internal pullup to VCC, the RESET output is push-pull active-high (no pullup resistor needed), and the WDI input is edge-sensitive with no external timing elements. Only a 0.1µF ceramic bypass capacitor from VCC to GND is recommended for noise suppression - not mandatory but strongly advised per the Typical Operating Circuit.

How does the watchdog timer in the MAX6865UK37D5S+T clear and expire?

The MAX6865UK37D5S+T watchdog timer clears on every rising or falling edge at the WDI pin and expires only if WDI remains static (high or low) for longer than 3.3s (typical). It does not count while RESET is asserted. Once expired, it triggers a full reset pulse for 300ms (D5 timeout), after which the timer resumes counting. This edge-clearing behavior prevents false timeouts during periodic polling or low-frequency I/O toggling.

What is the minimum supply voltage at which the MAX6865UK37D5S+T guarantees valid RESET output?

The MAX6865UK37D5S+T guarantees valid RESET output down to VCC = +1.1V, as explicitly stated in the Electrical Characteristics table under "Guaranteed Reset Valid to VCC = +1.1V". Below this voltage, the internal comparator and output driver may become indeterminate. This specification ensures reliable reset assertion during deep brownout conditions common in battery-discharge scenarios.

Is the MAX6865UK37D5S+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK37D5S+T shares the same 5-pin SOT23-5 package and pinout (RESET, GND, MR, WDI, VCC) with MAX6864, MAX6866, MAX6867, MAX6868, and MAX6869. However, it is not pin-compatible with MAX6861–MAX6863 (which use CT instead of WDI) or MAX6854–MAX6856 (which lack WDI). Pin compatibility is strictly limited to the MAX6864–MAX6869 subgroup with active-high RESET and WDI functionality.