Analog Devices Inc./Maxim Integrated MAX6865UK29D3S

Overview

The MAX6865UK29D3S 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 2.925V reset threshold (suffix "29"), 150ms minimum reset timeout (suffix "D3"), and integrated watchdog timer with 209s 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 MAX6865UK29D3S datasheet, MAX6865UK29D3S pinout, MAX6865UK29D3S application, or MAX6865UK29D3S 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-power systems requiring deterministic reset timing and watchdog supervision.

Technical Context

The MAX6865UK29D3S implements a dual-trigger reset architecture: it asserts reset when VCC falls below 2.925V (±2.5%), when MR is pulled low, or when the watchdog input (WDI) remains static beyond 209s (typ). Its internal watchdog timer clears on any WDI edge, MR assertion, or RESET assertion - enabling robust software execution monitoring without false timeouts.

Reset deassertion follows a fixed 150ms (min) timeout after VCC rises above threshold and MR deasserts; the push-pull active-high RESET output drives to ≥0.8×VCC when deasserted and ≤0.3V when asserted (at ISINK = 1.2mA, VCC ≥ 2.38V), ensuring reliable µP interface across 1.2V–5.5V supply range.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, surface-mount, lead-free compatible (RoHS-compliant).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK29D3S, MAX6864UK29D3S offers identical supervision accuracy and timing but requires active-low reset compatibility, while TPS3837K29 trades 10× higher current for TI's broader qualification and support ecosystem - making MAX6865UK29D3S optimal for long-life, watchdog-critical medical wearables.

Availability

MAX6865UK29D3S is available at Aetrix Electronics and suitable for glucose monitors, portable ECG devices, wireless patient alarms, and low-power wearable sensors requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK29D3S 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, mixed-signal, and power-management ICs for demanding industrial, medical, and communications applications.

The MAX6854–MAX6869 family delivers nanopower supervisory functionality targeting battery-constrained medical and portable electronics where reset reliability, ultra-low ICC, and integrated watchdog supervision are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6865UK29D3S?

The MAX6865UK29D3S has a factory-trimmed reset threshold voltage of 2.925V, with ±2.5% tolerance over -40°C to +85°C. This value is defined by the "29" suffix in the part number and is verified per Table 2 (Threshold Suffix Guide) in the official datasheet. The threshold remains stable across temperature, with normalized variation <±0.5% from -40°C to +85°C.

Does the MAX6865UK29D3S require external components for basic operation?

No, the MAX6865UK29D3S operates autonomously with no external components required. It integrates an internal 10kΩ pullup on MR, precision voltage reference, and timing elements for both reset timeout and watchdog functions. Only a 0.1µF VCC bypass capacitor is recommended for noise immunity - no resistors, capacitors, or additional ICs are needed for core supervision functionality.

How does the watchdog timer in the MAX6865UK29D3S respond to software activity?

The MAX6865UK29D3S watchdog timer resets on any rising or falling edge at the WDI pin and expires only if WDI remains static for >209s (typ). It clears instantly on MR assertion or RESET assertion, and resumes counting immediately after reset deassertion. This behavior ensures rapid detection of firmware hangs while tolerating long idle periods between software refreshes.

What is the minimum supply voltage at which the MAX6865UK29D3S guarantees valid RESET output?

The MAX6865UK29D3S guarantees valid RESET output down to VCC = +1.1V, as explicitly stated in the Electrical Characteristics table. Below this voltage, RESET may become indeterminate. This specification ensures reliable µP reset assertion during deep brownout conditions common in battery-powered medical devices nearing end-of-life.

Can the MAX6865UK29D3S be used with a microcontroller that has an active-low reset input?

No - the MAX6865UK29D3S provides an active-high push-pull RESET output, meaning it drives high during reset and low otherwise. To interface with an active-low reset input, an external inverter or logic gate is required. For direct compatibility, consider the pin-compatible MAX6864UK29D3S, which offers active-low push-pull RESET output with identical supervision parameters.