Analog Devices Inc./Maxim Integrated MAX6865UK37D2S+T

Overview

The MAX6865UK37D2S+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%), 40ms minimum reset timeout, and integrated watchdog timer with 3.3s typical timeout. It monitors VCC, responds to manual reset (MR), and asserts active-high push-pull RESET during brownout or watchdog expiration - used in battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK37D2S+T datasheet, MAX6865UK37D2S+T pinout, MAX6865UK37D2S+T application, or MAX6865UK37D2S+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, watchdog input (WDI) pulse detection as short as 150ns, and compatibility with 1.2V–5.5V supply rails.

Technical Context

This device belongs to the MAX6864–MAX6869 series with integrated watchdog timer and manual reset. Its functional architecture includes a precision voltage comparator for VCC monitoring, a digital watchdog timer cleared by WDI edges, and a programmable reset timeout generator - all operating from a single supply without external components.

The MAX6865UK37D2S+T implements an active-high push-pull RESET output referenced to VCC, MR with internal 10kΩ pullup, and WDI input accepting CMOS-compatible logic levels (VIH = 0.7×VCC, VIL = 0.3×VCC). It guarantees valid reset assertion even as VCC falls to +1.1V, enabling reliable operation in deep-brownout conditions.

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 MAX6864UK37D2S+T and TPS3836K33DBVR, the MAX6865UK37D2S+T uniquely combines active-high push-pull RESET, 3.7V threshold, 40ms timeout, and 3.3s watchdog - making it optimal for space-constrained, battery-critical medical wearables requiring deterministic reset behavior and firmware supervision.

Availability

MAX6865UK37D2S+T is available at Aetrix Electronics and suitable for glucose monitors, portable ECG devices, and wireless pulse oximeters requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK37D2S+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 MAX6864–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in battery-powered medical and portable electronics, emphasizing nanoscale ICC, robust transient immunity, and integrated watchdog reliability.

FAQ

What is the reset threshold voltage of the MAX6865UK37D2S+T?

The MAX6865UK37D2S+T has a factory-trimmed reset threshold of +3.700V with ±2.5% tolerance over temperature. This value is encoded in the '37' suffix and is specified for VCC falling conditions. The device guarantees valid reset assertion down to VCC = +1.1V, making it suitable for brownout detection in 3.3V systems with tight voltage margins.

Does the MAX6865UK37D2S+T include a watchdog timer?

Yes, the MAX6865UK37D2S+T includes an integrated watchdog timer with a typical timeout of 3.3s (S suffix), selectable via the WDI pin. The timer clears on any rising or falling edge at WDI and expires if WDI remains static longer than the timeout period - triggering a full reset sequence. This feature is confirmed in the Selector Guide and Electrical Characteristics table.

What is the reset timeout period for the MAX6865UK37D2S+T?

The MAX6865UK37D2S+T uses the D2 reset timeout option, providing a minimum reset pulse width of 40ms. This value is encoded in the 'D2' portion of the part number and is guaranteed across -40°C to +85°C. The timeout begins after VCC rises above the 3.7V threshold and MR is deasserted, ensuring sufficient hold time for µP initialization.

What type of RESET output does the MAX6865UK37D2S+T provide?

The MAX6865UK37D2S+T provides an active-high push-pull RESET output (pin 1), as confirmed by its placement in the Selector Guide under "Push-Pull ACTIVE HIGH" and its pin description. This eliminates the need for an external pullup resistor and allows direct connection to µPs with active-high reset inputs - unlike open-drain or active-low variants in the same family.

How is the manual reset (MR) input configured on the MAX6865UK37D2S+T?

The MR input (pin 3) on the MAX6865UK37D2S+T is active-low with an internal 10kΩ pullup to VCC. It accepts standard CMOS logic levels (VIH ≥ 0.7×VCC, VIL ≤ 0.3×VCC) and requires a minimum pulse width of 1µs. The device holds RESET asserted while MR is low and for the full 40ms timeout after MR returns high - enabling reliable hardware-initiated resets in field-deployed medical devices.