Analog Devices Inc./Maxim Integrated MAX6865UK32D3L+T

Overview

The MAX6865UK32D3L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.2V reset threshold (±2.5%), 150ms minimum reset timeout, manual reset input (MR), and watchdog timer with 209s typical timeout. It asserts active-high push-pull RESET during VCC brownout, MR assertion, or watchdog expiration-used in battery-powered medical monitors and portable instrumentation.

For engineers reviewing the MAX6865UK32D3L+T datasheet, MAX6865UK32D3L+T pinout, MAX6865UK32D3L+T application, or MAX6865UK32D3L+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, pin-selectable reset delay (not applicable here), and compatibility with 1.2V–5.5V supply rails in space-constrained embedded systems.

Technical Context

This device integrates voltage monitoring, manual reset control, and watchdog timer functionality into a single BiCMOS IC. Its reset logic combines VCC threshold detection (3.2V ±2.5%), MR-triggered assertion, and WDI edge-sensitive watchdog clearing-ensuring reliable µP initialization and fault recovery without external components.

The MAX6865UK32D3L+T uses an internal 10kΩ MR pullup and guarantees RESET deassertion only after VCC exceeds 3.2V and remains stable for ≥150ms. Watchdog timeout is fixed at 209s (typ), with WDI pulse width tolerance of 150ns and glitch rejection up to 200ns on MR.

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 MAX6865UK32D3L+T, the MAX6864UK32D3L+T offers identical supervision parameters but inverted RESET polarity-requiring schematic review for µP compatibility-while the TPS3837K32DBVR omits watchdog capability and draws nearly 10× more current, limiting suitability for multi-year battery operation.

Availability

MAX6865UK32D3L+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered instrumentation, wearable health trackers, and low-power IoT edge nodes requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK32D3L+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, and connectivity in harsh, size- and power-constrained environments.

The MAX6865UK32D3L+T belongs to the MAX68xx nanopower supervisory family, engineered specifically for ultra-long-life battery-operated systems where reset reliability, transient immunity, and sub-µA quiescent current are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6865UK32D3L+T?

The MAX6865UK32D3L+T has a factory-trimmed reset threshold of 3.200V 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 "32" corresponds to VTH = 3.2V. The MAX6865UK32D3L+T maintains this accuracy without external calibration.

Does the MAX6865UK32D3L+T support active-low reset output?

No, the MAX6865UK32D3L+T provides only active-high push-pull RESET output (pin 1). This is defined in the MAX6864/MAX6865/MAX6866 Pin Description section: for MAX6865, pin 1 is labeled RESET (active-high push-pull). Active-low variants exist (e.g., MAX6864UK32D3L+T), but the MAX6865UK32D3L+T does not support that configuration.

What is the watchdog timeout period for the MAX6865UK32D3L+T?

MAX6865UK32D3L+T features a watchdog timeout period of 209s typical (L suffix), with min/max values of 95s/487s over temperature. This is specified in Table 3 (Watchdog Timeout) and confirmed in the Ordering Information table where "L" follows the D3 timeout code. The timer resets on any WDI edge-rising or falling.

Can the MAX6865UK32D3L+T operate below 1.8V supply voltage?

Yes, the MAX6865UK32D3L+T operates from VCC = 1.2V to 5.5V and guarantees valid RESET output down to VCC = +1.1V. Electrical Characteristics confirm ICC = 170nA typ at VCC = 1.8V and RESET functionality maintained at 1.2V. Below 1.2V, the device may not assert RESET reliably, but the MAX6865UK32D3L+T remains functional through brownout.

Is the MR input of the MAX6865UK32D3L+T internally pulled up?

Yes, the MR input of the MAX6865UK32D3L+T includes an internal 10kΩ pullup resistor to VCC, as documented in the Pin Description section. This allows MR to be left unconnected or tied to VCC when unused. MR accepts CMOS logic levels and requires only a momentary switch to GND for manual reset-no external pullup or debounce circuitry is needed.