Analog Devices Inc./Maxim Integrated MAX6865UK29D3L+T

Overview

The MAX6865UK29D3L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.925V reset threshold, 150ms minimum reset timeout, manual reset input (MR), and watchdog timer with 209s typical timeout. It monitors VCC in battery-powered medical and portable electronics to ensure reliable µP initialization during brownout or software hang.

For engineers reviewing the MAX6865UK29D3L+T datasheet, MAX6865UK29D3L+T pinout, MAX6865UK29D3L+T application, or MAX6865UK29D3L+T equivalent, this page delivers verified electrical specs, validated pin functions, confirmed reset/watchdog timing behavior, and real-world design implications for low-power embedded systems.

Technical Context

This device integrates voltage monitoring, manual reset assertion, and watchdog timer functionality into a single BiCMOS IC. Its reset output remains asserted for ≥150ms after VCC rises above 2.925V and MR deasserts, and its watchdog timer triggers reset if WDI remains static for >209s (typ).

The internal 10kΩ MR pullup ensures robust manual reset initiation without external components, while guaranteed reset validity down to VCC = +1.1V enables operation across wide supply ranges in glucose monitors and patient devices.

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 MAX6864UK29D3S+T and TPS3836K33DBVR, the MAX6865UK29D3L+T uniquely combines ultra-low 170nA current, precise 2.925V threshold, 150ms reset delay, and long 209s watchdog - making it the only option meeting stringent power and reliability requirements for battery-powered medical wearables.

Availability

MAX6865UK29D3L+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, industrial handheld scanners, and low-power IoT edge sensors requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK29D3L+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 management, sensing, and interface applications in industrial, medical, and communications markets.

The MAX6854–MAX6869 family was engineered specifically for nanopower microprocessor supervision in battery-constrained portable medical and consumer electronics, emphasizing ultra-low ICC, guaranteed low-VCC operation, and integrated watchdog safety.

FAQ

What is the exact reset threshold voltage of the MAX6865UK29D3L+T?

The MAX6865UK29D3L+T has a factory-trimmed reset threshold of 2.925V, with guaranteed tolerance of ±2.5% (2.852V to 2.998V) over -40°C to +85°C. This value is defined by the "29" suffix per Table 2 in the datasheet and is laser-trimmed during production - not adjustable externally. The MAX6865UK29D3L+T uses this precise threshold to supervise 3.0V rails in portable medical devices where marginal brownout detection is critical.

Does the MAX6865UK29D3L+T include a watchdog timer, and what is its timeout behavior?

Yes, the MAX6865UK29D3L+T includes a watchdog timer with a typical timeout of 209s (L-suffix), ranging from 95s to 487s over temperature and process variation. The timer resets on any WDI edge (rising or falling) and triggers reset if WDI remains static beyond timeout. Unlike shorter-interval variants, the MAX6865UK29D3L+T's long watchdog period supports firmware with infrequent background tasks - such as daily sensor calibration - without risking spurious resets.

What is the function of Pin 1 on the MAX6865UK29D3L+T, and how does it differ from open-drain alternatives?

Pin 1 of the MAX6865UK29D3L+T is an active-high push-pull RESET output, meaning it actively drives high during reset assertion and low during deassertion - eliminating the need for an external pullup resistor. This differs from open-drain versions (e.g., MAX6856) which require external pullups and introduce additional leakage and board area. The MAX6865UK29D3L+T's push-pull architecture simplifies interface to µP reset inputs and improves noise immunity in compact PCB layouts.

How does the manual reset (MR) input behave on the MAX6865UK29D3L+T?

The MR input on the MAX6865UK29D3L+T is active-low with internal 10kΩ pullup to VCC, requiring <0.3×VCC for ≥1µs to assert reset. Reset remains active for the full 150ms timeout after MR returns high. No external debounce is needed due to 200ns glitch rejection. This behavior allows direct connection to momentary switches or CMOS logic - a key design advantage of the MAX6865UK29D3L+T in handheld medical instruments where user-initiated reset is essential.

Is the MAX6865UK29D3L+T compatible with 1.8V systems, and what is its minimum operating voltage?

Yes, the MAX6865UK29D3L+T operates from VCC = 1.2V to 5.5V and guarantees valid reset output down to VCC = +1.1V - fully supporting 1.8V logic domains. At 1.8V, its supply current is 170nA (typ), and RESET output maintains VOH ≥ 0.8×VCC with 200µA source capability. This makes the MAX6865UK29D3L+T suitable for modern ultra-low-voltage microcontrollers and sensors where traditional supervisors fail below 2.0V.