Analog Devices Inc./Maxim Integrated MAX6865UK45D4L+T

Overview

The MAX6865UK45D4L+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 4.500V reset threshold (±2.5%), and a 1200ms minimum reset timeout period. It integrates voltage monitoring, manual reset input (MR), and watchdog timer functionality with L-suffix 209s typical watchdog timeout, designed for reliable power-up/brownout protection in battery-powered medical and portable electronics.

For engineers reviewing the MAX6865UK45D4L+T datasheet, MAX6865UK45D4L+T pinout, MAX6865UK45D4L+T application, or MAX6865UK45D4L+T equivalent, key selection criteria include its active-high push-pull RESET output, guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), and compatibility with noisy low-power systems requiring precise timing and minimal quiescent current.

Technical Context

The MAX6865UK45D4L+T implements a dual-trigger reset architecture: it asserts reset when VCC falls below 4.500V, when MR is pulled low, or when the watchdog timer expires after 209s (typ) of WDI inactivity. Its internal watchdog clears on any WDI edge (rising or falling), supporting robust software execution monitoring in safety-critical embedded firmware.

This device uses BiCMOS process technology (2848 transistors) and features an internally pulled-up MR input (10kΩ), a dedicated WDI pin tolerant to 150ns pulses, and a push-pull active-high RESET output referenced to VCC with VOH ≥ 0.8×VCC at ISOURCE = 500µA and VOL ≤ 0.3V at ISINK = 1.2mA.

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 MAX6864UK45D4L+T and TPS3837K33DBVR, the MAX6865UK45D4L+T uniquely delivers active-high RESET, 209s watchdog, and 170nA current in one 5-pin SOT23 package - enabling longer battery life and safer firmware recovery in compact medical and portable designs.

Availability

MAX6865UK45D4L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, industrial handheld scanners, and smart wearable health trackers requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6865UK45D4L+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 MAX6865UK45D4L+T belongs to the MAX6854–MAX6869 nanopower µP supervisory family, engineered for ultra-low-current voltage monitoring and watchdog protection in battery-constrained portable and medical electronics.

FAQ

What is the exact reset threshold voltage of the MAX6865UK45D4L+T?

The MAX6865UK45D4L+T has a factory-trimmed reset threshold voltage of +4.500V with ±2.5% tolerance over temperature (−40°C to +85°C). This value is defined by the "45" suffix in the part number and is verified per Table 2 (Threshold Suffix Guide) in the official datasheet. The threshold remains stable across voltage and temperature, with normalized variation ≤±0.5% from −40°C to +85°C.

Does the MAX6865UK45D4L+T support active-high or active-low reset output?

The MAX6865UK45D4L+T features an active-high push-pull RESET output (pin 1), meaning it drives high during reset assertion and returns low upon deassertion. This is confirmed by its pin description and functional diagram in the datasheet. Unlike MAX6864 variants, it does not require an external pullup resistor and directly interfaces with µPs expecting high-asserted reset signals.

What is the watchdog timeout period for the MAX6865UK45D4L+T?

The MAX6865UK45D4L+T implements a watchdog timeout period of 209s typical (L-suffix), with min/max values of 95s and 487s over temperature and voltage. The watchdog timer clears on any rising or falling edge at the WDI pin (pin 4) and expires only if WDI remains static beyond this period, triggering a full reset sequence with the configured 1200ms timeout.

Can the MAX6865UK45D4L+T operate down to 1.2V supply voltage?

Yes, the MAX6865UK45D4L+T is fully specified to operate from VCC = 1.2V to 5.5V. Its reset function remains guaranteed down to VCC = +1.1V, and supply current is characterized at 1.2V (190nA typ). This makes it suitable for single-cell Li-ion, NiMH, or coin-cell applications where supply voltage drops significantly during discharge.

Is the manual reset input (MR) of the MAX6865UK45D4L+T internally pulled up?

Yes, the MR pin (pin 3) of the MAX6865UK45D4L+T includes an internal 10kΩ pullup resistor to VCC, as documented in the Pin Description section. This allows direct connection of a momentary switch from MR to GND without external components. The MR input accepts CMOS-compatible logic levels and rejects glitches shorter than 200ns.