Analog Devices Inc./Maxim Integrated MAX6865UK35D1L+T

Overview

The MAX6865UK35D1L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring, manual reset input (MR), and watchdog timer (WDI) functionality. It asserts an active-high push-pull RESET output when VCC drops below 3.500V (factory-trimmed threshold), MR is pulled low, or the watchdog expires after 209s (typ). Designed for ultra-low-power systems, it draws only 170nA (typ) supply current and guarantees valid reset operation down to VCC = +1.1V - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK35D1L+T datasheet, MAX6865UK35D1L+T pinout, MAX6865UK35D1L+T application, or MAX6865UK35D1L+T equivalent, key selection criteria include its 3.5V reset threshold, 10ms minimum reset timeout, 209s watchdog period, and compatibility with noisy, low-voltage embedded power rails requiring guaranteed reset assertion at VCC ≥ 1.1V.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over -40°C to +85°C, coupled with a digital watchdog timer that clears on any WDI edge and triggers reset if no transition occurs within 209s (typ). The internal reset timeout generator uses a temperature-stable RC oscillator, delivering a guaranteed minimum 10ms deassertion hold time after VCC recovery and MR release.

The MR input features 10kΩ internal pullup, 1µs minimum pulse width support, and 200ns glitch rejection; the WDI input accepts CMOS-level signals with 0.3×VCC/0.7×VCC logic thresholds and tolerates 150ns pulses. RESET output is push-pull active-high, sourcing up to 500µA at VOH ≥ 0.8×VCC (VCC ≥ 2.38V) and sinking capability disabled - consistent with active-high drive requirements of modern µPs.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact footprint (2.9mm × 1.6mm × 1.1mm) suitable for space-constrained portable medical and IoT designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK35D1L+T and TPS3836K33DBVR, the MAX6865UK35D1L+T uniquely delivers active-high reset drive, 3.5V precision threshold, and nanopower consumption - making it the sole option for new designs requiring long-life operation with modern active-high-reset µPs.

Availability

MAX6865UK35D1L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, and portable pulse oximeters requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK35D1L+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 markets.

The MAX6854–MAX6869 family was designed specifically for ultra-low-power microprocessor supervision in battery-critical portable medical and handheld electronics - emphasizing nanoscale current, guaranteed low-VCC operation, and integrated watchdog reliability.

FAQ

What is the exact reset threshold voltage of the MAX6865UK35D1L+T?

The MAX6865UK35D1L+T has a factory-trimmed reset threshold of 3.500V, with ±2.5% tolerance over -40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "35" corresponds to VTH = 3.500V (min 3.413V, typ 3.500V, max 3.588V). The MAX6865UK35D1L+T maintains this precision without external calibration or resistor networks.

Does the MAX6865UK35D1L+T support active-high or active-low reset output?

The MAX6865UK35D1L+T provides an active-high push-pull RESET output, as specified in its pin description (Pin 1 function) and Selector Guide. Unlike the MAX6864 variant, it asserts RESET high during fault conditions and deasserts low after timeout. This matches the reset input polarity of modern ARM Cortex-M and RISC-V microcontrollers requiring active-high assertion.

What is the watchdog timeout period for the MAX6865UK35D1L+T, and how is it configured?

The MAX6865UK35D1L+T features a watchdog timeout period of 209s (typ), designated by the "L" suffix in its part number. This is a fixed, factory-programmed value - no external components or pin strapping is required. The watchdog timer clears on any rising or falling edge at the WDI pin and triggers reset if no edge occurs within 209s, making it suitable for long-duration firmware tasks in the MAX6865UK35D1L+T application.

Can the MAX6865UK35D1L+T operate reliably at VCC = 1.2V?

Yes, the MAX6865UK35D1L+T is fully specified to operate from VCC = 1.2V to 5.5V, with guaranteed reset functionality down to VCC = +1.1V. Its 170nA supply current and valid RESET output at 1.2V enable use in single-cell Li-ion or alkaline systems where voltage sags below 1.5V during discharge - a critical capability confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables for the MAX6865UK35D1L+T.

Is a bypass capacitor required for the MAX6865UK35D1L+T, and what value is recommended?

Yes, a 0.1µF ceramic bypass capacitor is required between VCC (Pin 5) and GND (Pin 2) for stable operation. This is explicitly stated in the Pin Description section and Applications Information. The capacitor suppresses high-frequency noise on the monitored supply rail, preventing false resets caused by transient coupling - essential for robust performance in portable medical devices where the MAX6865UK35D1L+T is commonly deployed.