Analog Devices Inc./Maxim Integrated MAX6865UK22D1S+T

Overview

The MAX6865UK22D1S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring (2.235V reset threshold), manual reset input (MR), and watchdog timer (3.3s typical timeout) with ultra-low 170nA typical supply current. It asserts an active-low push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, ensuring reliable system initialization in battery-powered medical and portable electronics.

For engineers reviewing the MAX6865UK22D1S+T datasheet, MAX6865UK22D1S+T pinout, MAX6865UK22D1S+T application, or MAX6865UK22D1S+T equivalent, key selection criteria include its 2.235V factory-trimmed reset threshold, 10ms minimum reset timeout, 3.3s watchdog period, guaranteed reset validity down to VCC = +1.1V, and immunity to short VCC transients - all critical for low-power embedded reset integrity.

Technical Context

This device integrates a precision bandgap-based voltage monitor, a digital watchdog timer with edge-triggered WDI input, and a manual reset debounced input with internal 10kΩ pullup. Its reset logic combines asynchronous VCC-fall detection with a monolithic timeout generator that holds RESET asserted for ≥10ms after VCC recovery and MR release.

The MAX6865UK22D1S+T uses BiCMOS process technology to achieve nanoscale leakage control, enabling stable operation across –40°C to +85°C while maintaining <25nA max input leakage on MR and WDI pins and <25nA open-drain RESET leakage when deasserted.

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 MAX6865UK22D1S+T, MAX6864UK22D1S+T trades push-pull drive for open-drain flexibility, while TPS3836K22DBVR sacrifices watchdog capability and nanoscale current for lower unit cost and TI ecosystem alignment - neither offers identical feature parity.

Availability

MAX6865UK22D1S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered diagnostics, and low-power wireless sensors requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for MAX6865UK22D1S+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 high-performance analog and mixed-signal ICs for power, sensing, and interface applications, with emphasis on reliability and integration for demanding environments.

The MAX68xx family delivers nanopower supervisory functions specifically for battery-critical systems like patient monitors and handheld diagnostics, prioritizing ultra-low ICC, precise threshold accuracy, and robust watchdog supervision.

FAQ

What is the exact reset threshold voltage of the MAX6865UK22D1S+T?

The MAX6865UK22D1S+T has a factory-trimmed reset threshold of 2.235V, with guaranteed tolerance of ±2.5% over –40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "22" corresponds to 2.235V nominal. The device asserts RESET when VCC falls below this threshold and holds it asserted for ≥10ms after VCC rises above it.

Does the MAX6865UK22D1S+T include a watchdog timer, and what is its timeout?

Yes, the MAX6865UK22D1S+T includes a watchdog timer with a typical timeout of 3.3s, indicated by the "S" suffix in the part number. The timer expires if the WDI pin remains static (high or low) longer than this period, triggering a reset pulse for the configured 10ms timeout. The timer clears on any WDI edge, MR assertion, or active RESET.

What type of reset output does the MAX6865UK22D1S+T provide?

The MAX6865UK22D1S+T provides an active-low push-pull RESET output (Pin 1), referenced to VCC. It drives low actively during reset and pulls high to VCC when deasserted - no external pullup is required. Output voltage specifications include VOL ≤ 0.3V at ISINK = 1.2mA (VCC ≥ 2.38V) and VOH ≥ 0.8×VCC at ISOURCE = 500µA.

Can the MAX6865UK22D1S+T operate reliably at very low supply voltages?

Yes, the MAX6865UK22D1S+T guarantees valid RESET assertion down to VCC = +1.1V, as explicitly stated in the Electrical Characteristics table. Below this, reset behavior is not specified. Its operational range starts at VCC = +1.2V, and it maintains 170nA typical supply current even at 1.8V, making it suitable for single-cell Li-ion and alkaline systems.

Is the MAX6865UK22D1S+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK22D1S+T shares the same 5-pin SOT23-5 package and pinout (VCC, WDI, MR, GND, RESET) with MAX6864/MAX6866/MAX6867–MAX6869 variants. However, it is not pin-compatible with MAX6861–MAX6863 (which use CT pin) or MAX6854–MAX6856 (which lack WDI). Always verify functional configuration using the Selector Guide before substitution.