Analog Devices Inc./Maxim Integrated MAX6865UK21D5S+T

Overview

The MAX6865UK21D5S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, a factory-trimmed 2.100V reset threshold (±2.5%), 600ms minimum reset timeout (D5 option), and integrated watchdog timer with 3.3s typical timeout (S suffix). It monitors VCC, responds to manual reset (MR) input, and asserts an active-high push-pull RESET output - ideal for battery-powered glucose monitors and portable medical devices requiring guaranteed reset validity down to VCC = +1.1V.

For engineers reviewing the MAX6865UK21D5S+T datasheet, MAX6865UK21D5S+T pinout, MAX6865UK21D5S+T application, or MAX6865UK21D5S+T equivalent, key selection criteria include its 2.100V reset threshold tolerance, 600ms D5 timeout, S-suffix 3.3s watchdog period, active-high push-pull output configuration, and immunity to short VCC transients below 40µs at 100mV overdrive.

Technical Context

The MAX6865UK21D5S+T implements a dual-monitoring architecture: a precision voltage detector triggers reset when VCC falls below 2.100V (±2.5%), and a watchdog timer expires if the WDI input remains static beyond 3.3s (typ). Its internal 10kΩ MR pullup enables direct CMOS switch interfacing without external components.

Reset assertion persists for ≥600ms after VCC rises above threshold and MR deasserts, while the watchdog timer clears on any WDI edge, MR assertion, or active reset - ensuring robust recovery from software hangs without false triggers during normal operation.

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 MAX6864UK21D5S+T and TPS3836K21DBVR, the MAX6865UK21D5S+T uniquely delivers active-high push-pull RESET, ultra-low 170nA ICC, and integrated 3.3s watchdog - making it optimal for space-constrained, long-life medical and portable electronics where reset polarity and power efficiency are critical.

Availability

MAX6865UK21D5S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring devices, and cellular IoT sensors requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6865UK21D5S+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 high-performance analog and mixed-signal ICs for power, sensing, and timing applications in industrial, medical, and consumer systems.

The MAX6854–MAX6869 family delivers nanopower supervisory functions - specifically engineered for battery-critical portable medical and handheld electronics needing guaranteed reset behavior at ultra-low current.

FAQ

What is the exact reset threshold voltage of the MAX6865UK21D5S+T?

The MAX6865UK21D5S+T has a factory-trimmed reset threshold of 2.100V with ±2.5% tolerance over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "21" corresponds to 2.100V nominal. The device guarantees valid reset assertion down to VCC = +1.1V, supporting reliable brownout detection even near end-of-battery life.

Does the MAX6865UK21D5S+T include a watchdog timer, and what is its timeout period?

Yes, the MAX6865UK21D5S+T includes an integrated watchdog timer with a typical timeout period of 3.3s, indicated by the "S" suffix in the part number. The timer clears on any rising or falling edge at the WDI pin, and expires only if WDI remains static beyond this period. This behavior is documented in Table 3 (Watchdog Timeout) and applies specifically to MAX6864–MAX6869 variants like the MAX6865UK21D5S+T.

What type of reset output does the MAX6865UK21D5S+T provide, and how is it configured?

The MAX6865UK21D5S+T provides an active-high push-pull RESET output on Pin 1, as confirmed by its position in the Selector Guide (row MAX6865) and Pin Description section. This configuration eliminates the need for an external pullup resistor and allows direct connection to microprocessor reset inputs expecting high-active signaling - distinguishing it from open-drain or active-low variants in the same family.

What is the minimum reset timeout period for the MAX6865UK21D5S+T, and how is it selected?

The MAX6865UK21D5S+T has a fixed minimum reset timeout period of 600ms, designated by the "D5" suffix in the part number per Table 4 (Reset Timeout Periods). Unlike MAX6861–MAX6863, it does not feature a CT pin for dynamic timeout selection - the D5 option is factory-configured and cannot be altered in-circuit.

How does the MAX6865UK21D5S+T handle manual reset input, and what is the internal pullup value?

The MAX6865UK21D5S+T features an active-low MR input (Pin 3) with a factory-integrated 10kΩ pullup resistor to VCC, as specified in the Pin Description and Electrical Characteristics tables. This allows direct connection of a momentary switch from MR to GND for manual reset, with no external components required. MR pulse width must exceed 1µs, and the device rejects glitches shorter than 200ns.