Analog Devices Inc./Maxim Integrated MAX6865UK33D2S+T

Overview

The MAX6865UK33D2S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring 3.3V reset threshold (±2.5%), 40ms minimum reset timeout, active-high push-pull RESET output, manual reset input (MR), and watchdog timer with 3.3s typical timeout. It monitors VCC down to 1.1V and draws only 170nA typical supply current, enabling reliable power-on reset and brownout protection in ultra-low-power portable medical and consumer devices.

For engineers reviewing the MAX6865UK33D2S+T datasheet, MAX6865UK33D2S+T pinout, MAX6865UK33D2S+T application, or MAX6865UK33D2S+T equivalent, key selection criteria include its guaranteed reset validity at VCC = 1.1V, immunity to sub-40µs VCC transients, MR glitch rejection of 200ns, and compatibility with 1.2V–5.5V supply rails - critical for battery-powered glucose monitors and wearables requiring long shelf life and robust fault recovery.

Technical Context

This device integrates three core functions: precision voltage monitoring with factory-trimmed 3.3V threshold (VTH = 3.3V ±2.5%), a 40ms minimum reset timeout timer (D2 option), and a watchdog circuit that triggers reset if WDI remains static beyond 3.3s (S suffix). Its BiCMOS process ensures stable operation across –40°C to +85°C while maintaining nanoscale quiescent current.

The MAX6865UK33D2S+T uses an active-high push-pull RESET output referenced to VCC, eliminating external pullup components. MR is internally pulled up to VCC via 10kΩ, and WDI accepts CMOS-level transitions with 150ns pulse-width support - enabling direct interface with µP GPIO without level-shifting.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SOT-23 packages. Dimensions: 2.9mm × 1.6mm × 1.1mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK33D2S+T, the L-suffix variant trades faster fault response for extended watchdog window, while TPS3837K33DBVR sacrifices watchdog capability and ultra-low power for lower unit cost - making MAX6865UK33D2S+T optimal for compact, battery-constrained medical and wearable systems demanding both precision reset and responsive firmware supervision.

Availability

MAX6865UK33D2S+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign loggers, smart wearables, and industrial handheld scanners requiring stable component supply, long-term lifecycle support, and lead-free compliance.

Supply support for MAX6865UK33D2S+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 MAX6865UK33D2S+T belongs to Maxim's nanopower µP supervisory family, engineered specifically for ultra-low-power portable and battery-operated systems requiring guaranteed reset behavior, watchdog supervision, and minimal quiescent current.

FAQ

What is the exact reset threshold voltage of the MAX6865UK33D2S+T?

The MAX6865UK33D2S+T has a factory-trimmed reset threshold of 3.3V with ±2.5% tolerance (3.218V to 3.383V), as defined by the "33" suffix in its part number per Maxim's Threshold Suffix Guide. This value is guaranteed over –40°C to +85°C and ensures reliable reset assertion when the 3.3V supply falls below specification.

Does the MAX6865UK33D2S+T require external components for basic operation?

No, the MAX6865UK33D2S+T operates autonomously with no external components required: it features an internal 10kΩ pullup on MR, precision voltage reference, and integrated watchdog oscillator. Only a 0.1µF ceramic bypass capacitor on VCC is recommended for noise immunity - no resistors, capacitors, or timing components are needed for reset or watchdog functionality.

How does the watchdog timer in the MAX6865UK33D2S+T respond to software errors?

The MAX6865UK33D2S+T watchdog timer expires if the WDI input remains static (high or low) for longer than 3.3s (typical). A rising or falling edge on WDI clears the timer - enabling firmware to "kick" the watchdog by toggling a GPIO. If code execution stalls in a loop without WDI activity, the timer expires and asserts RESET for 40ms, forcing a controlled MCU reboot.

Can the MAX6865UK33D2S+T operate reliably at very low supply voltages?

Yes, the MAX6865UK33D2S+T guarantees valid RESET assertion down to VCC = 1.1V, and its supply current remains stable (170nA typ) across 1.2V–5.5V. This allows safe operation during deep brownout conditions where other supervisors fail, ensuring deterministic reset behavior even as batteries deplete in medical or wearable devices.

What is the function of Pin 1 (RESET) on the MAX6865UK33D2S+T?

Pin 1 of the MAX6865UK33D2S+T is an active-high push-pull RESET output. It drives high during reset (e.g., at power-up or brownout) and low when deasserted. Unlike open-drain variants, it requires no external pullup resistor and directly interfaces with µP reset inputs rated for VCC-referenced logic levels - simplifying design and reducing component count.