Analog Devices Inc./Maxim Integrated MAX6858UK29D4+

Overview

The MAX6858UK29D4+ from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, providing voltage monitoring, manual reset input, and fixed 1200ms minimum reset timeout. It asserts an active-low push-pull RESET when VCC drops below 2.925V (typ), during MR assertion, or at power-up/brownout - ensuring reliable µP initialization in ultra-low-power systems. It is used in battery-powered medical devices such as glucose monitors where supply stability and low quiescent current are critical.

For engineers reviewing the MAX6858UK29D4+ datasheet, MAX6858UK29D4+ pinout, MAX6858UK29D4+ application, or MAX6858UK29D4+ equivalent, key selection criteria include its 2.925V factory-trimmed reset threshold, 1200ms reset timeout, 170nA typical supply current at 2.5V, guaranteed RESET validity down to VCC = +1.1V, and immunity to short VCC transients - all validated for -40°C to +85°C operation.

Technical Context

The MAX6858UK29D4+ integrates a precision voltage monitor with ±2.5% threshold accuracy, a fixed 1200ms internal reset timeout timer, and a manual reset input (MR) with 250ns propagation delay and 1µs minimum pulse width. Its push-pull active-low RESET output sinks up to 1.2mA at VCC ≥ 2.38V while maintaining VOL ≤ 0.3V.

Unlike watchdog-equipped variants (e.g., MAX6864–MAX6869), the MAX6858UK29D4+ omits WDI functionality and I.C. pins - instead using Pins 1 and 2 as internally connected terminals tied to GND for enhanced noise immunity. It supports no external components and operates across VCC = 1.2V to 5.5V.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free (RoHS-compliant), footprint-compatible with industry-standard 5-lead SOT23.

Key Features

Applications

Equivalent & Alternatives

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

Compared with the MAX6858UK29D4+, the TPS3836K33DBVR offers superior threshold accuracy but consumes 7x more current, while the MAX6361KA29D3+ shares the same threshold but provides only 300ms timeout - making the MAX6858UK29D4+ uniquely suited for applications demanding both ultra-low ICC and extended reset hold time.

Availability

The MAX6858UK29D4+ is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, and handheld diagnostic tools requiring stable component supply across extended product lifecycles and global manufacturing sites.

Supply support for MAX6858UK29D4+ 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 industrial, medical, and communications applications.

The MAX6858UK29D4+ belongs to the MAX6854–MAX6869 nanopower supervisory family, engineered specifically for battery-critical portable medical and wearables where sub-µA supply current and guaranteed low-voltage reset behavior are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6858UK29D4+?

The MAX6858UK29D4+ has a factory-trimmed reset threshold of 2.925V (typical), with ±2.5% tolerance over temperature (-40°C to +85°C). This value corresponds to the "29" suffix in the part number per Maxim's Threshold Suffix Guide (Table 2), and is validated across the full operating voltage range of 1.2V to 5.5V.

Does the MAX6858UK29D4+ include a watchdog timer function?

No, the MAX6858UK29D4+ does not include a watchdog timer. It is a voltage-monitoring and manual-reset supervisory circuit only. Watchdog functionality is present only in MAX6864–MAX6869 variants (e.g., MAX6864UK29D3S+), which feature WDI input and selectable watchdog timeout periods.

What is the purpose of Pins 1 and 2 (I.C.) on the MAX6858UK29D4+?

Pins 1 and 2 on the MAX6858UK29D4+ are labeled "I.C." (Internally Connected) and are tied together internally to GND. The datasheet explicitly recommends connecting both pins to system ground to improve noise immunity - they are not unused or NC pins, and grounding them is required for specified performance.

What reset timeout period is implemented in the MAX6858UK29D4+?

The "D4" suffix in MAX6858UK29D4+ specifies a minimum reset timeout period of 1200ms, with typical and maximum values of 1800ms and 2400ms respectively. This fixed timeout is factory-programmed and cannot be adjusted externally - unlike MAX6861–MAX6863 variants that use the CT pin for selection.

Is the RESET output of the MAX6858UK29D4+ open-drain or push-pull?

The MAX6858UK29D4+ features a push-pull active-low RESET output. It actively drives low during reset assertion and high (to VCC) when deasserted - eliminating the need for an external pullup resistor. This differs from open-drain variants like MAX6856 or MAX6860, which require external pullups.