Analog Devices Inc./Maxim Integrated MAX6865UK29D4S+T

Overview

The MAX6865UK29D4S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.925V reset threshold, 1200ms minimum reset timeout, active-low push-pull RESET output, manual reset (MR) input, and watchdog timer with 3.3s typical timeout. It monitors VCC in battery-powered portable electronics to ensure reliable µP initialization during power-up, brownout, or software lockup.

For engineers reviewing the MAX6865UK29D4S+T datasheet, MAX6865UK29D4S+T pinout, MAX6865UK29D4S+T application, or MAX6865UK29D4S+T equivalent, key selection criteria include guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), MR glitch rejection (200ns), and compatibility with 1.2V–5.5V supply rails.

Technical Context

This device integrates three core functions: precision voltage monitoring with ±2.5% threshold accuracy over temperature, a configurable watchdog timer that clears on WDI edge transitions and expires after 3.3s (typ), and a manual reset input with internal 10kΩ pullup and 1µs minimum pulse width support. The reset assertion logic combines VCC undervoltage, MR low, and WDI timeout events using wired-OR behavior.

The internal reset timeout generator provides fixed 1200ms (D4 option) delay after VCC recovery or MR deassertion, with guaranteed minimum tRP of 1200ms and typical 1800ms. Reset deassertion occurs only after both VCC exceeds VTH + hysteresis and the timeout elapses - no race condition between supply rise and timer expiration.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, 2.9mm × 1.6mm × 1.1mm body, lead-free (RoHS-compliant), thermal pad not present.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK29D4S+T, MAX6361KA29D3+T removes watchdog capability to reduce cost and current draw, while TPS3839G33DBVR offers tighter 3.3V threshold tolerance but sacrifices configurability, manual reset, and long-tail reset timing needed for complex boot sequences.

Availability

MAX6865UK29D4S+T is available at Aetrix Electronics and suitable for portable medical devices, wearable electronics, industrial handheld scanners, and smart remote controls requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6865UK29D4S+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 demanding environments.

The MAX68xx family delivers nanopower supervisory solutions optimized for battery-critical portable and medical electronics, emphasizing ultra-low ICC, wide VCC range, and robust reset timing under transient conditions.

FAQ

What is the exact reset threshold voltage of the MAX6865UK29D4S+T?

The MAX6865UK29D4S+T has a factory-trimmed reset threshold of 2.925V, with ±2.5% tolerance over the full -40°C to +85°C operating temperature range. This value is confirmed by the "29" suffix in the part number per Maxim's Threshold Suffix Guide (Table 2), and is guaranteed by design-not just typical-across all production units.

Does the MAX6865UK29D4S+T support active-high reset output?

No, the MAX6865UK29D4S+T provides only active-low push-pull RESET output (pin 1). The "65" in the part number identifies it as a member of the MAX6864–MAX6866 series with active-low reset; active-high variants like MAX6865UK29D4S+T do not exist-the MAX6865 designation specifically denotes active-low push-pull configuration.

What is the watchdog timeout period for MAX6865UK29D4S+T, and how is it cleared?

The MAX6865UK29D4S+T features a 3.3s typical watchdog timeout (S suffix), with min/max of 1.5s/7.75s. The internal timer clears on any rising or falling edge at the WDI pin (pin 4), and also resets automatically when MR is asserted or RESET is active-ensuring immediate recovery from firmware hangs without requiring precise timing alignment.

Can the MAX6865UK29D4S+T operate reliably at VCC = 1.2V?

Yes, the MAX6865UK29D4S+T is fully specified to operate at VCC = 1.2V, with guaranteed reset assertion validity down to VCC = +1.1V. At 1.2V, supply current remains at 190nA (typ), and all timing parameters-including 1200ms reset timeout and 250ns MR-to-reset delay-remain within datasheet limits per Electrical Characteristics table.

Is an external pullup resistor required for the RESET output of MAX6865UK29D4S+T?

No, the MAX6865UK29D4S+T uses a push-pull active-low RESET output (pin 1), which actively drives low and high-no external pullup is needed. Unlike open-drain variants, this configuration eliminates reliance on board-level resistors, reducing BOM count and ensuring predictable rise/fall times even under capacitive loads up to 50pF.