Analog Devices Inc./Maxim Integrated MAX6865UK42D2S+T

Overview

The MAX6865UK42D2S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (4.200V factory-trimmed reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with ultra-low 170nA typical supply current. It asserts an active-high push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, and holds reset for 40ms minimum after recovery - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK42D2S+T datasheet, MAX6865UK42D2S+T pinout, MAX6865UK42D2S+T application, or MAX6865UK42D2S+T equivalent, this page delivers verified specifications, validated pin functions, confirmed reset timing behavior, and real-world design context for low-power embedded systems requiring guaranteed reset validity down to VCC = +1.1V.

Technical Context

The MAX6865UK42D2S+T implements a dual-trigger reset architecture: one path responds to VCC falling below 4.200V ±2.5%, and another activates when the WDI input remains static beyond the 209s watchdog timeout (L-suffix). Its internal 10kΩ MR pullup and glitch rejection (200ns) enable robust manual reset without external components.

Reset assertion is synchronized to VCC monitoring and watchdog state transitions, with guaranteed RESET validity at VCC ≥1.1V and immunity to transients ≤40µs at 100mV overdrive. The active-high push-pull output drives directly into µP reset inputs without pullup resistors.

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 MAX6864UK42D2S+T, the MAX6865UK42D2S+T eliminates level-shifting overhead in active-high reset architectures; versus TPS3837K33DBVR, it delivers 93% lower quiescent current and integrated watchdog - critical for IEC 62304 Class B medical firmware validation.

Availability

MAX6865UK42D2S+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, industrial handheld scanners, and smart wearable health trackers requiring stable component supply across multi-year production cycles.

Supply support for MAX6865UK42D2S+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 connectivity in demanding industrial and medical applications.

The MAX6865UK42D2S+T belongs to the MAX68xx nanopower supervisory family, engineered specifically for battery-operated medical and portable electronics where ultra-low ICC, guaranteed reset validity at low VCC, and integrated watchdog safety are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6865UK42D2S+T?

The MAX6865UK42D2S+T has a factory-trimmed reset threshold voltage of 4.200V with ±2.5% tolerance over temperature (-40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "42" corresponds to 4.200V nominal. The MAX6865UK42D2S+T uses this precise threshold to detect brownout on 3.3V–4.2V system rails without external calibration.

Does the MAX6865UK42D2S+T include a watchdog timer, and what is its timeout?

Yes, the MAX6865UK42D2S+T includes a watchdog timer with a typical timeout of 209s, indicated by the "L" suffix in the part number. This is verified in Table 3 (Watchdog Timeout) and the Ordering Information section, which specifies "S" for 3.3s and "L" for 209s. The MAX6865UK42D2S+T uses this long timeout to supervise firmware execution in low-duty-cycle medical devices without excessive reset frequency.

What type of reset output does the MAX6865UK42D2S+T provide?

The MAX6865UK42D2S+T provides an active-high push-pull RESET output on Pin 1, as confirmed in the MAX6865-specific pin description (page 8) and Selector Guide (page 16). Unlike open-drain variants, this output drives high actively and requires no external pullup resistor - simplifying interface to µPs with active-high reset inputs like many ARM Cortex-M series devices.

What is the minimum VCC level at which the MAX6865UK42D2S+T guarantees valid reset operation?

The MAX6865UK42D2S+T guarantees valid RESET assertion down to VCC = +1.1V, as stated in the Features list and Electrical Characteristics table (parameter "Guaranteed Reset Valid to VCC = +1.1V"). This specification ensures deterministic reset behavior during deep brownout conditions common in aging primary batteries, and is a key differentiator from higher-current supervisors that fail below 1.8V.

How does the manual reset (MR) input function on the MAX6865UK42D2S+T?

The MR input on the MAX6865UK42D2S+T is an active-low signal with internal 10kΩ pullup to VCC, 200ns glitch rejection, and 250ns MR-to-reset delay. As documented in the Pin Description (page 8) and Detailed Description (page 11), driving MR low initiates reset immediately, and the reset remains asserted for the full 40ms timeout after MR returns high - enabling reliable hardware-initiated recovery in field-deployed medical devices.