Analog Devices Inc./Maxim Integrated MAX6865UK35D2S+T

Overview

The MAX6865UK35D2S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.5V reset threshold (±2.5%), 40ms minimum reset timeout, manual reset input (MR), and watchdog timer with 3.3s typical timeout. It monitors VCC in battery-powered medical and portable electronics to ensure reliable µP startup and fault recovery.

For engineers reviewing the MAX6865UK35D2S+T datasheet, MAX6865UK35D2S+T pinout, MAX6865UK35D2S+T application, or MAX6865UK35D2S+T equivalent, key selection criteria include its active-high push-pull RESET output, guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), and compatibility with noisy low-power systems requiring minimal quiescent current.

Technical Context

This device integrates voltage monitoring, a manual reset input (MR), and a watchdog timer (WDI) in a single BiCMOS IC. The watchdog clears on any WDI edge and expires if WDI remains static beyond 3.3s (typ), triggering a 40ms (min) reset pulse. Reset assertion occurs when VCC falls below 3.5V, MR is pulled low, or watchdog times out.

The internal 10kΩ MR pullup ensures robust default high state, and the push-pull active-high RESET output drives directly to VCC without external components. Timing is temperature-stable: reset delay (tRD) is 40µs max, MR-to-reset delay (tMRD) is 250ns max, and reset timeout (tRP) maintains ±1% variation across –40°C to +85°C.

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 MAX6864UK35D2S+T and TPS3837K33DBVR, the MAX6865UK35D2S+T uniquely delivers active-high push-pull RESET, 170nA ICC, and integrated 3.3s watchdog in one 5-pin SOT23 - enabling simpler, longer-lasting, and more robust supervision in space-constrained portable systems.

Availability

MAX6865UK35D2S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered IoT sensors, handheld diagnostic tools, and low-power wearables requiring stable component supply and long-term lifecycle support.

Supply support for MAX6865UK35D2S+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, mixed-signal, and power management ICs for demanding industrial, medical, and communications applications.

The MAX6854–MAX6869 family was engineered specifically for nanopower microprocessor supervision in battery-critical systems, combining ultra-low ICC, accurate voltage monitoring, manual reset, and configurable watchdog functionality in minimal footprint.

FAQ

What is the exact reset threshold voltage of the MAX6865UK35D2S+T?

The MAX6865UK35D2S+T features a factory-trimmed reset threshold of 3.500V with ±2.5% tolerance (3.413V to 3.588V) across –40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "35" corresponds to 3.5V nominal. The threshold remains stable over temperature, with normalized variation ≤±0.5% from –40°C to +85°C per Figure toc06.

Does the MAX6865UK35D2S+T require external components for basic operation?

No, the MAX6865UK35D2S+T operates autonomously with no external components required. Its internal 10kΩ MR pullup, precision voltage reference, and watchdog oscillator eliminate need for resistors, capacitors, or crystals. A 0.1µF bypass capacitor on VCC is recommended for noise immunity but not strictly required for functional operation per datasheet Typical Operating Circuit.

How does the watchdog timer in the MAX6865UK35D2S+T function, and what is its timeout period?

The MAX6865UK35D2S+T watchdog timer expires if the WDI input remains static (high or low) for longer than 3.3s (typical), triggering a 40ms (min) active-high RESET pulse. The timer clears on any WDI edge (≥150ns wide), including those generated by firmware polling. Timeout is specified as "S" suffix in ordering code and is stable across temperature per Figure toc04.

What is the purpose of the active-high push-pull RESET output in the MAX6865UK35D2S+T?

The active-high push-pull RESET output in the MAX6865UK35D2S+T directly drives µP reset inputs that require an asserted-high signal, eliminating external inverters or pullup resistors. It sources up to 500µA at VOH ≥0.8×VCC and sinks up to 1.2mA at VOL ≤0.3V, ensuring robust logic-level compatibility with 1.8V–5.5V µPs without additional interface circuitry.

Is the MAX6865UK35D2S+T compatible with systems experiencing fast VCC transients?

Yes, the MAX6865UK35D2S+T is designed to reject short VCC transients: it will not assert reset for pulses <40µs duration when overdrive is 100mV (per Figure toc05). This immunity prevents false resets caused by switching noise or load dumps in portable equipment, and is validated across the full –40°C to +85°C operating range.