Analog Devices Inc./Maxim Integrated MAX6867UK29D3S+T

Overview

The MAX6867UK29D3S+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 2.925V reset threshold, 150ms minimum reset timeout, and integrated watchdog timer with 3.3s typical timeout. It monitors VCC, responds to manual reset (MR), and asserts active-low push-pull RESET during brownout or watchdog expiration - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6867UK29D3S+T datasheet, MAX6867UK29D3S+T pinout, MAX6867UK29D3S+T application, or MAX6867UK29D3S+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), WDI pulse detection as short as 150ns, and compatibility with noisy low-power systems requiring no external components.

Technical Context

The MAX6867UK29D3S+T implements a dual-monitoring architecture: a precision voltage detector with ±2.5% threshold accuracy over temperature and a digital watchdog timer that clears on any WDI edge (rising or falling) and expires if WDI remains static beyond 3.3s (typ). Its internal 10kΩ MR pullup and glitch rejection (200ns) enable direct switch interfacing without external debounce.

RESET assertion is synchronized across three independent triggers - VCC falling below 2.925V, MR low, or WDI timeout - with a fixed 150ms (min) deassertion delay after recovery. The push-pull active-low output drives directly into µP reset inputs, sinking up to 1.2mA at VCC ≥ 2.38V while maintaining VOL ≤ 0.3V.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, footprint compatible with industry-standard 5-pin SOT23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK29D3S+T, the MAX6867UK29D3S+T offers identical core supervision but is optimized for space-constrained medical wearables requiring minimal external components; versus TPS3836K29DBVR, it delivers integrated watchdog and lower quiescent current at the expense of TI's broader second-source availability.

Availability

MAX6867UK29D3S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered instrumentation, and industrial handheld equipment requiring stable component supply across extended product lifecycles.

Supply support for MAX6867UK29D3S+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 management, sensing, and interface applications in demanding industrial and medical environments.

The MAX6854–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in battery-critical systems, integrating voltage monitoring, manual reset, and watchdog functionality into a single 5-pin SOT23 package.

FAQ

What is the exact reset threshold voltage of the MAX6867UK29D3S+T?

The MAX6867UK29D3S+T has a factory-trimmed reset threshold voltage of 2.925V, with ±2.5% tolerance over the full -40°C to +85°C operating temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "29" corresponds to 2.925V nominal. The MAX6867UK29D3S+T maintains this accuracy without calibration or external components.

Does the MAX6867UK29D3S+T require an external pullup resistor on the RESET pin?

No, the MAX6867UK29D3S+T uses a push-pull active-low RESET output, which actively drives both high and low states - eliminating the need for an external pullup resistor. This is explicitly stated in the Pin Description section for MAX6867: "Push-pull RESET outputs are referenced to VCC." The MAX6867UK29D3S+T is therefore compatible with µP reset inputs requiring driven logic levels without additional passive components.

What is the watchdog timeout behavior of the MAX6867UK29D3S+T?

The MAX6867UK29D3S+T features a watchdog timer with a typical timeout of 3.3s (S suffix), with a minimum of 1.5s and maximum of 7.75s over temperature. The timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static (high or low) beyond the timeout period. During reset assertion, the watchdog timer is halted and resumes counting only after RESET deasserts - a behavior confirmed in the Functional Diagram and Detailed Description sections.

Can the MAX6867UK29D3S+T operate reliably at VCC = 1.2V?

Yes, the MAX6867UK29D3S+T is fully specified to operate from VCC = 1.2V to 5.5V. Its RESET output remains valid down to VCC = +1.1V, and supply current is characterized at 1.2V (7µA max when reset asserted, 170nA typ when deasserted). This enables use in single-cell alkaline or lithium systems where voltage sags below 1.5V during discharge - a key capability documented in the Absolute Maximum Ratings and Electrical Characteristics tables.

How does the MAX6867UK29D3S+T handle short VCC transients?

The MAX6867UK29D3S+T is designed to reject short-duration VCC transients: it typically does not assert RESET for glitches under 40µs duration when the overdrive is 100mV (i.e., VCC dips 100mV below the 2.925V threshold). This immunity is graphically verified in the "Maximum VCC Transient Duration vs. Reset Threshold Overdrive" curve (Figure MAX684 toc05), ensuring robust operation in electrically noisy portable equipment - a critical feature for the MAX6867UK29D3S+T in medical and industrial applications.