Analog Devices Inc./Maxim Integrated MAX6865UK39D6L+T

Overview

The MAX6865UK39D6L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (3.9V reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with ultra-low 170nA typical supply current. It asserts an active-high push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, ensuring reliable µP initialization in battery-powered medical and portable systems.

For engineers reviewing the MAX6865UK39D6L+T datasheet, MAX6865UK39D6L+T pinout, MAX6865UK39D6L+T application, or MAX6865UK39D6L+T equivalent, this device serves as a precision, low-quiescent-current supervisor for systems requiring guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients, and robust watchdog supervision of firmware execution.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% reset threshold accuracy over temperature, coupled with a digitally timed watchdog circuit that clears on any WDI edge and expires if no transition occurs within 209s (typ). The internal reset timeout is fixed at 1200ms (D6 option), and the active-high push-pull RESET output is referenced to VCC with VOH ≥ 0.8×VCC at ISOURCE = 500µA.

The MR input features 10kΩ internal pullup, 1µs minimum pulse width support, and 200ns glitch rejection. Watchdog timing is factory-trimmed and exhibits <±15% variation over –40°C to +85°C, with guaranteed operation across VCC = 1.2V to 5.5V.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, 2.9mm × 1.6mm footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK39D6L+T, the MAX6864UK39D6S+T offers identical supervision architecture but tighter watchdog response, while the TPS3839G33DBVR reduces cost and complexity at the expense of integrated watchdog capability and longer reset hold time.

Availability

MAX6865UK39D6L+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered IoT sensors, industrial handheld terminals, and low-power wearables requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK39D6L+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, interface, and reliability-critical applications.

The MAX6854–MAX6869 family delivers nanopower supervisory functions targeting ultra-long-life battery-operated systems where reset accuracy, low ICC, and integrated watchdog are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6865UK39D6L+T?

The MAX6865UK39D6L+T has a factory-trimmed reset threshold of 3.900V (min), 3.900V (typ), and 3.998V (max) over –40°C to +85°C. This corresponds to the "39" suffix per Maxim's Threshold Suffix Guide (Table 2), enabling precise supervision of 3.3V and 3.6V logic rails without external resistor dividers.

Does the MAX6865UK39D6L+T support active-high or active-low reset output?

The MAX6865UK39D6L+T provides an active-high push-pull RESET output (Pin 1). When asserted, RESET goes high to VCC; when deasserted, it pulls low. This configuration eliminates external pullup resistors and ensures defined logic levels across the full 1.2V–5.5V VCC range, including down to VCC = +1.1V.

What is the watchdog timeout behavior of the MAX6865UK39D6L+T?

The MAX6865UK39D6L+T features a watchdog timeout of 95s (min), 209s (typ), and 487s (max), denoted by the "L" suffix. The internal timer resets on any rising or falling edge at WDI (Pin 4); if no edge occurs within this period, RESET asserts for the full 1200ms timeout (D6 option), then deasserts automatically.

Can the MAX6865UK39D6L+T operate reliably at VCC = 1.5V?

Yes. The MAX6865UK39D6L+T is fully specified from VCC = 1.2V to 5.5V and guarantees valid RESET assertion down to VCC = +1.1V. At 1.5V, all electrical characteristics-including 170nA typical ICC, 3.9V threshold accuracy, and WDI edge detection-remain functional per datasheet limits.

Is the MAX6865UK39D6L+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK39D6L+T uses the standard 5-pin SOT23-5 pinout shared across MAX6864–MAX6869 variants (Pin 1: RESET, Pin 2: GND, Pin 3: MR, Pin 4: WDI, Pin 5: VCC). It is not pin-compatible with MAX6861–MAX6863 (which use CT instead of WDI on Pin 4) or MAX6854–MAX6856 (which lack WDI entirely).