Analog Devices Inc./Maxim Integrated MAX6865UK45D5S+T

Overview

The MAX6865UK45D5S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, integrating voltage monitoring (4.500V factory-trimmed reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout). It asserts an active-high push-pull RESET output during VCC brownout, MR assertion, or watchdog expiration, with guaranteed reset validity down to VCC = +1.1V. It targets ultra-low-power portable medical and consumer devices requiring reliable power-on reset and firmware crash recovery.

For engineers reviewing the MAX6865UK45D5S+T datasheet, MAX6865UK45D5S+T pinout, MAX6865UK45D5S+T application, or MAX6865UK45D5S+T equivalent, key selection criteria include its 4.500V reset threshold tolerance (±2.5%), 450ms minimum reset timeout, 209s watchdog period, 170nA typical supply current at 2.5V, and compatibility with 1.2V–5.5V VCC operation - all critical for battery-powered glucose monitors and handheld diagnostics.

Technical Context

This device implements a precision bandgap-based voltage monitor with 2.5% threshold accuracy over -40°C to +85°C, coupled to a digital timeout counter that enforces a fixed 450ms (D5) reset assertion period after VCC recovery or MR release. Its watchdog logic detects WDI edge transitions and resets the internal timer on every rising or falling edge, preventing false timeouts during normal software execution.

The MAX6865UK45D5S+T uses BiCMOS process technology to achieve 170nA typical ICC while maintaining robust noise immunity: it rejects VCC transients ≤40µs at 100mV overdrive and guarantees valid RESET output down to VCC = +1.1V, enabling use in deep-brownout scenarios common in Li-ion battery discharge profiles.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact 2.9mm × 1.6mm footprint with 0.95mm height, optimized for space-constrained portable PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK45D5S+T and TPS3838K33DBVR, the MAX6865UK45D5S+T uniquely delivers active-high RESET, 4.500V precision threshold, and 209s watchdog in one nanopower package - essential for clinical-grade portable diagnostics requiring deterministic reset behavior and long-term firmware reliability.

Availability

MAX6865UK45D5S+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, handheld diagnostic scanners, and wireless pulse oximeters requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK45D5S+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 high-performance analog and mixed-signal ICs for power, sensing, and connectivity applications in industrial, medical, and automotive markets.

The MAX6854–MAX6869 family was engineered specifically for ultra-low-power microprocessor supervision in battery-operated medical and portable electronics, emphasizing nanopower consumption, precision voltage thresholds, and integrated watchdog safety.

FAQ

What is the exact reset threshold voltage of the MAX6865UK45D5S+T?

The MAX6865UK45D5S+T has a factory-trimmed reset threshold voltage of 4.500V with ±2.5% tolerance over -40°C to +85°C. This value is fixed and encoded in the "45" suffix per Maxim's Threshold Suffix Guide (Table 2), and does not require external calibration or resistor networks. The MAX6865UK45D5S+T maintains this accuracy across its full operating temperature range and supply voltage (1.2V–5.5V).

Does the MAX6865UK45D5S+T support active-high or active-low reset output?

The MAX6865UK45D5S+T provides an active-high push-pull RESET output (pin 1), meaning it drives the output high during reset assertion and low when deasserted. This is confirmed by its pin description (page 8) and Selector Guide (page 16), which list MAX6865 under "Push-Pull ACTIVE HIGH". Unlike MAX6864 or MAX6866 variants, the MAX6865UK45D5S+T does not offer open-drain or active-low configurations.

What is the watchdog timeout period for the MAX6865UK45D5S+T?

The MAX6865UK45D5S+T features a watchdog timeout period of 209s typical (minimum 95s, maximum 487s), denoted by the "L" suffix in its part number. This long interval is designed for supervising firmware tasks with extended execution cycles, such as clinical data logging or sensor calibration routines, without requiring frequent WDI toggling. The MAX6865UK45D5S+T watchdog timer resets on every WDI edge and remains disabled while RESET is asserted.

Can the MAX6865UK45D5S+T operate down to 1.2V supply voltage?

Yes, the MAX6865UK45D5S+T operates across a VCC range of 1.2V to 5.5V and guarantees valid RESET output down to VCC = +1.1V. At 1.2V, its supply current is 190nA typical, and its reset threshold remains accurate within specification. This makes the MAX6865UK45D5S+T suitable for single-cell Li-ion or alkaline battery systems where voltage sags below 2.0V during discharge - a capability verified in the Absolute Maximum Ratings and Electrical Characteristics tables.

Is the MAX6865UK45D5S+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK45D5S+T uses the standard 5-pin SOT23-5 package and shares identical pinout with MAX6864, MAX6866, MAX6867, MAX6868, and MAX6869 (pin 1 = RESET, pin 2 = GND, pin 3 = MR, pin 4 = WDI, pin 5 = VCC). However, RESET polarity differs: MAX6865UK45D5S+T is active-high, while MAX6864/MAX6866 are active-low. Thus, direct PCB replacement requires verification of µP reset pin logic polarity before substitution.