Analog Devices Inc./Maxim Integrated MAX6865UK37D2L+T

Overview

MAX6865UK37D2L+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%), 40ms minimum reset timeout, and integrated watchdog timer with 209s typical timeout. 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 MAX6865UK37D2L+T datasheet, MAX6865UK37D2L+T pinout, MAX6865UK37D2L+T application, or MAX6865UK37D2L+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, MR glitch rejection (200ns), and compatibility with noisy low-power systems requiring deterministic reset behavior under voltage droop or software lockup.

Technical Context

The MAX6865UK37D2L+T implements a dual-trigger reset architecture: one path responds to VCC falling below 3.7V ±2.5%, the other activates when the watchdog input (WDI) remains static beyond 209s (typ). Its internal timer ensures RESET remains asserted for ≥40ms after VCC recovery or WDI edge detection.

It features an internally pulled-up MR input (10kΩ), CMOS-compatible WDI with 150ns pulse width support, and push-pull active-high RESET output referenced to VCC - eliminating external pullups while maintaining logic-level compatibility across 1.2V–5.5V supply range.

Key Specifications

Pinout & Package

MAX6865UK37D2L+T uses a 5-pin SOT23-5 package (JEDEC MO-178AA), footprint-compatible with industry-standard supervisory ICs. Pin 1 is RESET (active-high push-pull), Pin 2 is GND, Pin 3 is MR (active-low manual reset), Pin 4 is WDI (watchdog input), and Pin 5 is VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK37D2L+T and TPS3837K33DBVR, the MAX6865UK37D2L+T uniquely combines ultra-low 170nA ICC, 3.7V precision threshold, 40ms reset timeout, and 209s watchdog - making it optimal for long-life, safety-aware portable medical electronics requiring both voltage and firmware supervision.

Availability

MAX6865UK37D2L+T is available at Aetrix Electronics and suitable for glucose monitors, portable ECG recorders, wireless pulse oximeters, and smart inhaler sensors requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK37D2L+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 power, sensing, and interface applications in industrial, medical, and communications markets.

The MAX6865UK37D2L+T belongs to the MAX68xx nanopower supervisory family, engineered specifically for battery-constrained medical wearables and portable diagnostics requiring simultaneous voltage monitoring and firmware execution supervision.

FAQ

What is the exact reset threshold voltage of MAX6865UK37D2L+T?

The MAX6865UK37D2L+T has a factory-trimmed reset threshold of 3.7V with ±2.5% tolerance, corresponding to a guaranteed range of 3.608V to 3.793V at -40°C to +85°C. This value is defined by the "37" suffix per Maxim's Threshold Suffix Guide (Table 2), and is measured during final test with VCC falling conditions. The MAX6865UK37D2L+T uses this precise threshold to initiate reset when monitored 3.3V or 3.6V rails dip below specification.

Does MAX6865UK37D2L+T require external components for basic operation?

No, the MAX6865UK37D2L+T operates autonomously with no external resistors or capacitors required. Its MR input includes a 10kΩ internal pullup to VCC, the RESET output is push-pull active-high (no pullup needed), and timing is fully internal. Only a 0.1µF ceramic bypass capacitor from VCC to GND is recommended for noise immunity - a standard practice for all ICs, not a functional requirement unique to the MAX6865UK37D2L+T.

How does the watchdog timer in MAX6865UK37D2L+T respond to firmware errors?

The MAX6865UK37D2L+T watchdog timer expires if the WDI input remains static (high or low) for longer than 209s (typical), triggering a full reset cycle. The timer clears on any WDI edge (rising or falling), so firmware must toggle WDI at least once per timeout period. During reset assertion, the timer halts and resumes counting only after RESET deasserts - ensuring deterministic recovery from infinite loops or stalled code in the MAX6865UK37D2L+T supervised system.

Can MAX6865UK37D2L+T operate reliably at VCC = 1.2V?

Yes, the MAX6865UK37D2L+T is fully specified from VCC = 1.2V to 5.5V and guarantees RESET output validity down to VCC = +1.1V. At 1.2V, supply current remains ultra-low (≤370nA), reset threshold accuracy holds within ±2.5%, and MR input thresholds scale proportionally (VIL = 0.3×VCC, VIH = 0.7×VCC). This makes the MAX6865UK37D2L+T suitable for single-cell lithium or alkaline systems nearing end-of-life discharge.

What is the function of Pin 1 (RESET) on MAX6865UK37D2L+T?

Pin 1 of the MAX6865UK37D2L+T is the active-high push-pull RESET output. It drives high during reset assertion (when VCC < 3.7V, MR is low, or WDI timeout occurs) and low when deasserted. Unlike open-drain variants, it requires no external pullup and sources/sinks current directly - simplifying interface to µPs with active-high reset inputs. The MAX6865UK37D2L+T RESET output remains valid and monotonic across its full 1.2V–5.5V VCC range.