Analog Devices Inc./Maxim Integrated MAX6865UK27D4S+T

Overview

MAX6865UK27D4S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.700V reset threshold (suffix '27'), 1200ms minimum reset timeout (suffix 'D4'), and watchdog timer with 3.3s typical timeout (suffix 'S'). It monitors VCC, responds to manual reset (MR), and triggers reset on watchdog expiration - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK27D4S+T datasheet, MAX6865UK27D4S+T pinout, MAX6865UK27D4S+T application, or MAX6865UK27D4S+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), push-pull active-high RESET output, and compatibility with noisy low-voltage systems requiring long battery life.

Technical Context

The MAX6865UK27D4S+T implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over -40°C to +85°C, paired with a digital watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 3.3s (typ). Its internal 10kΩ MR pullup and glitch rejection (200ns) enable robust manual reset without external components.

Reset assertion is synchronized to VCC falling below 2.700V, with a fixed 1200ms (min) deassertion delay after VCC rises above threshold and MR deasserts; the watchdog timeout is independent of VCC and stable across temperature (±15% variation over full range).

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 MAX6864UK27D4S+T and TPS3837K27DBVR, the MAX6865UK27D4S+T uniquely delivers active-high reset, ultra-low 170nA current, and integrated watchdog - making it optimal for space-constrained, battery-critical medical and wearable systems requiring both power efficiency and firmware reliability.

Availability

MAX6865UK27D4S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, smart wearables, and industrial sensor nodes requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6865UK27D4S+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 MAX6854–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in battery-operated medical and portable electronics, emphasizing nanoscale current consumption, robust reset timing, and integrated watchdog safety.

FAQ

What is the exact reset threshold voltage of the MAX6865UK27D4S+T?

The MAX6865UK27D4S+T has a factory-trimmed reset threshold of 2.700V, with ±2.5% tolerance over the full -40°C to +85°C temperature range. This value is confirmed by the '27' suffix in the part number and verified in Table 2 (Threshold Suffix Guide) of the official datasheet. The MAX6865UK27D4S+T asserts reset when VCC falls below this threshold and holds reset for 1200ms after VCC recovers.

Does the MAX6865UK27D4S+T require external components for basic operation?

No, the MAX6865UK27D4S+T operates autonomously with no external components required for core supervision. It integrates an internal 10kΩ pullup on MR, precision voltage reference, watchdog oscillator, and reset timer. Only a 0.1µF ceramic bypass capacitor on VCC to GND is recommended for noise immunity - no resistors, capacitors, or diodes are needed for reset generation or watchdog functionality in the MAX6865UK27D4S+T.

What is the watchdog timeout behavior of the MAX6865UK27D4S+T?

The MAX6865UK27D4S+T features a watchdog timer with 3.3s typical timeout (S-suffix), clearing on any rising or falling edge at WDI and expiring if WDI remains static beyond that period. Upon expiration, it asserts the active-high RESET output for the full 1200ms reset timeout. The MAX6865UK27D4S+T watchdog is temperature-stable (±15%) and independent of VCC, ensuring consistent firmware supervision across operating conditions.

Can the MAX6865UK27D4S+T operate reliably at VCC = 1.2V?

Yes, the MAX6865UK27D4S+T is fully specified from VCC = 1.2V to 5.5V and guarantees valid reset assertion down to VCC = +1.1V. At 1.2V, its supply current remains ultra-low (190nA typ), reset threshold accuracy holds within ±2.5%, and RESET output maintains proper logic levels (VOH ≥ 0.8×VCC, VOL ≤ 0.3V). This makes the MAX6865UK27D4S+T suitable for single-cell alkaline or LiFePO₄ systems.

How does the MAX6865UK27D4S+T handle short VCC transients?

The MAX6865UK27D4S+T is designed to ignore brief supply disturbances: it tolerates VCC transients ≤40µs in duration when the overdrive is 100mV above its 2.700V threshold, as shown in the "Maximum VCC Transient Duration vs. Reset Threshold Overdrive" graph. This immunity prevents false resets caused by switching noise, ESD events, or load-step transients - a critical feature for the MAX6865UK27D4S+T in portable medical equipment with shared power rails.