Analog Devices Inc./Maxim Integrated MAX6865UK45D3S+T

Overview

The MAX6865UK45D3S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 4.500V reset threshold (suffix "45"), 150ms minimum reset timeout (suffix "D3"), and watchdog timer with 3.3s typical timeout (suffix "S"). It monitors VCC, responds to manual reset (MR), and triggers reset on watchdog expiration - designed for battery-critical applications like glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK45D3S+T datasheet, MAX6865UK45D3S+T pinout, MAX6865UK45D3S+T application, or MAX6865UK45D3S+T equivalent, key selection criteria include its active-high push-pull RESET output, guaranteed reset validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, and compatibility with 1.2V–5.5V supply rails - all critical for low-power embedded system reliability.

Technical Context

This device integrates three core functions: precision voltage monitoring with ±2.5% threshold accuracy over temperature, a manual reset input with 250ns MR-to-reset delay and internal 10kΩ pullup, and a watchdog timer that clears on any WDI edge and expires after 3.3s (typ) if inactive. The reset assertion persists for ≥150ms after VCC exceeds 4.500V and MR deasserts.

Its BiCMOS process enables stable operation across –40°C to +85°C with no external components required. The active-high push-pull RESET output sources up to 500µA at VCC ≥ 2.38V (VOH ≥ 0.8×VCC) and sinks <0.3V at 1.2mA load - ensuring robust interfacing with modern µP reset inputs without external pullups.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SOT-23 layouts. Thermal pad not present; standard reflow profile applies.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK45D3S+T, the L-suffix variant offers longer watchdog coverage for complex firmware, while TPS3837K33DBVR provides a lower-cost reset-only alternative at 3.3V - neither is pin- or functionally identical, requiring design review for substitution.

Availability

MAX6865UK45D3S+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, industrial handheld terminals, and smart energy meters requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK45D3S+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 industrial, medical, and communications markets.

The MAX6854–MAX6869 family delivers nanopower supervisory functions - specifically engineered for battery-operated medical and portable equipment where ultra-low ICC and guaranteed reset behavior under brownout are mandatory.

FAQ

What is the reset threshold voltage of the MAX6865UK45D3S+T?

The MAX6865UK45D3S+T has a factory-trimmed reset threshold of +4.500V, with ±2.5% tolerance over temperature. This value is encoded in the "45" suffix and is guaranteed across –40°C to +85°C. The device asserts reset when VCC falls below this threshold and holds reset asserted for ≥150ms after VCC rises above it. This precise threshold ensures compatibility with 4.5V nominal rails in portable medical and industrial systems.

Does the MAX6865UK45D3S+T include a watchdog timer, and what is its timeout?

Yes, the MAX6865UK45D3S+T includes a watchdog timer with a typical timeout of 3.3 seconds, indicated by the "S" suffix in the part number. The timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static beyond this period. It triggers a full reset for the configured 150ms timeout. This behavior is confirmed in the Electrical Characteristics table and Functional Diagram of the MAX6865UK45D3S+T datasheet.

What type of reset output does the MAX6865UK45D3S+T provide?

The MAX6865UK45D3S+T provides an active-high push-pull RESET output (Pin 1), as specified in its Pin Description section and Selector Guide. Unlike open-drain variants, it does not require an external pullup resistor and can directly drive the reset input of most microprocessors. Its VOH is ≥0.8×VCC at 500µA source current, ensuring clean logic-high assertion across its 1.2V–5.5V operating range.

What is the supply current consumption of the MAX6865UK45D3S+T?

The MAX6865UK45D3S+T consumes only 170nA typical supply current (ICC) at VCC = 1.8V and +25°C, as measured under no-load conditions with reset deasserted. This ultra-low quiescent current is critical for extending battery life in always-on portable devices. ICC remains below 400nA across the full –40°C to +85°C temperature range and 1.2V–5.5V supply, per the Electrical Characteristics table.

Is the MAX6865UK45D3S+T compatible with 1.8V microcontrollers?

Yes, the MAX6865UK45D3S+T operates reliably with 1.8V microcontrollers. Its VCC range is 1.2V to 5.5V, and its active-high push-pull RESET output delivers VOH ≥ 0.8×VCC (≥1.44V at 1.8V) while sourcing 200µA - well within standard 1.8V CMOS input high thresholds. Additionally, its MR input accepts 0.3×VCC low and 0.7×VCC high logic levels, ensuring direct interface without level shifters.