Analog Devices Inc./Maxim Integrated MAX6865UK43D1S+T

Overview

The MAX6865UK43D1S+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 4.300V reset threshold (±2.5%), 10ms 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, power-up, or watchdog expiration - used in battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK43D1S+T datasheet, MAX6865UK43D1S+T pinout, MAX6865UK43D1S+T application, or MAX6865UK43D1S+T equivalent, this page delivers verified electrical parameters, functional pin roles, real-world use cases, and validated alternative parts for low-power µP reset and watchdog supervision in space-constrained, long-life embedded systems.

Technical Context

This device integrates three core functions: precision voltage monitoring with hysteresis (0.5% of VTH), a glitch-immune manual reset input (250ns MR-to-reset delay, 1µs minimum pulse width), and a watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 3.3s (typ). The internal 10kΩ MR pullup eliminates external components.

It operates across VCC = 1.2V to 5.5V and guarantees valid RESET output down to VCC = 1.1V. Its nanopower design enables operation in energy-harvesting and coin-cell applications where quiescent current directly impacts battery life - confirmed by ICC = 170nA (typ) at VCC = 1.8V and TA = +25°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 MAX6865UK43D1S+T, MAX6864UK43D1S+T offers identical core supervision but omits CT-based timeout flexibility, while TPS3836K33DBVR trades nanopower and watchdog capability for lower cost and simpler integration in non-critical reset-only roles.

Availability

MAX6865UK43D1S+T is available at Aetrix Electronics and suitable for battery-powered medical devices, portable diagnostics equipment, and low-power industrial sensors requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6865UK43D1S+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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, medical, and communications applications.

The MAX6854–MAX6869 family was designed specifically for ultra-low-power microprocessor supervision in portable and battery-operated systems, integrating voltage monitoring, manual reset, and watchdog functionality in minimal footprint.

FAQ

What is the exact reset threshold voltage of the MAX6865UK43D1S+T?

The MAX6865UK43D1S+T has a factory-trimmed reset threshold voltage of 4.300V, with guaranteed tolerance of ±2.5% over the -40°C to +85°C temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "43" corresponds to VTH = 4.300V (min 4.193V, typ 4.300V, max 4.408V). The MAX6865UK43D1S+T uses this precise threshold to supervise 3.3V or 5V rails without external calibration.

Does the MAX6865UK43D1S+T include a watchdog timer, and what is its timeout?

Yes, the MAX6865UK43D1S+T includes an integrated watchdog timer with a typical timeout of 3.3s, 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, triggering a reset for the configured 10ms timeout. This behavior is documented in Table 3 (Watchdog Timeout) and applies specifically to MAX6864–MAX6869 variants like the MAX6865UK43D1S+T.

What is the function of Pin 4 (WDI) on the MAX6865UK43D1S+T?

Pin 4 on the MAX6865UK43D1S+T is the Watchdog Input (WDI), which must be toggled (low-to-high or high-to-low) at least once every 3.3s to prevent watchdog timeout and subsequent reset assertion. The internal timer resets on each WDI edge and remains inactive while RESET is asserted. This pin enables firmware-level supervision of code execution flow - a key differentiator from basic reset supervisors. The MAX6865UK43D1S+T's WDI accepts CMOS-compatible logic levels and rejects pulses shorter than 150ns.

Is the MAX6865UK43D1S+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK43D1S+T shares the same 5-pin SOT23-5 package and pinout as MAX6864/MAX6866 variants (Pin 1: RESET, Pin 2: GND, Pin 3: MR, Pin 4: WDI, Pin 5: VCC), making it mechanically and electrically pin-compatible within that subgroup. However, it is not pin-compatible with MAX6861–MAX6863 (which use Pin 1 for CT) or MAX6854–MAX6856 (which lack WDI). Always verify pin mapping using the "MAX6864/MAX6865/MAX6866 Pin Description" section before substitution.

What is the minimum supply voltage at which the MAX6865UK43D1S+T guarantees valid reset output?

The MAX6865UK43D1S+T guarantees valid reset output down to VCC = 1.1V, as explicitly stated in the Electrical Characteristics table under "Guaranteed Reset Valid to VCC = +1.1V". Below this voltage, RESET output behavior is not specified. This specification ensures reliable reset assertion during deep brownout conditions - critical for preventing corrupted memory writes or undefined MCU states. The MAX6865UK43D1S+T maintains this guarantee across its full operating temperature range (-40°C to +85°C).