Analog Devices Inc./Maxim Integrated MAX6866UK33D6S+T

Overview

The MAX6866UK33D6S+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 3.3V reset threshold (±2.5%), 1200ms minimum reset timeout, manual reset input (MR), and watchdog timer with 3.3s typical timeout. It monitors VCC in battery-powered portable systems to ensure reliable µP initialization during power-up, brownout, or software hang conditions.

For engineers reviewing the MAX6866UK33D6S+T datasheet, MAX6866UK33D6S+T pinout, MAX6866UK33D6S+T application, or MAX6866UK33D6S+T equivalent, key selection criteria include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), open-drain active-low RESET output, and compatibility with low-voltage µPs operating from 1.2V to 5.5V.

Technical Context

This device integrates three core functions: precision voltage monitoring with hysteresis (0.5% of VTH), a manual reset input with 1µs minimum pulse width and 200ns glitch rejection, and a watchdog timer that triggers reset if WDI remains static beyond 3.3s (typ). The internal timer ensures reset assertion persists for ≥1200ms after VCC recovery or MR/WDT event clearance.

The MAX6866UK33D6S+T uses BiCMOS process technology (2848 transistors) and operates across –40°C to +85°C. Its open-drain RESET output requires an external pullup; it sinks ≤0.3V at 1.2mA when asserted and leaks ≤25nA when deasserted. MR is internally pulled up to VCC via 10kΩ.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact footprint (2.9mm × 1.6mm × 1.1mm) suitable for space-constrained portable PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK33D6S+T and TPS3838K33DBVR, the MAX6866UK33D6S+T uniquely combines nanopower operation, open-drain flexibility, and integrated watchdog-enabling single-chip reliability in space- and energy-constrained portable designs without layout or firmware compromise.

Availability

MAX6866UK33D6S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered IoT sensors, wearable fitness trackers, and industrial handheld scanners requiring stable component supply across extended product lifecycles.

Supply support for MAX6866UK33D6S+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 consumer applications.

The MAX6854–MAX6869 family was designed specifically for ultra-low-power microprocessor supervision in battery-critical portable equipment, integrating voltage monitoring, manual reset, and watchdog functionality into minimal SOT23 footprints.

FAQ

What is the exact reset threshold voltage for MAX6866UK33D6S+T?

The MAX6866UK33D6S+T has a factory-trimmed nominal reset threshold of 3.3V, with guaranteed tolerance of ±2.5% (3.218V to 3.383V at TA = –40°C to +85°C). This value is fixed per device and corresponds to the "33" suffix in the part number, referencing Table 2 (Threshold Suffix Guide) in the datasheet.

Does MAX6866UK33D6S+T require external components for basic operation?

No, the MAX6866UK33D6S+T requires no external components for core supervision functionality. Its internal 10kΩ MR pullup, precision voltage reference, and watchdog timer eliminate the need for external resistors or capacitors. A 0.1µF bypass capacitor on VCC is recommended for noise immunity but not strictly required for functional operation.

How does the watchdog timer in MAX6866UK33D6S+T interact with the manual reset input?

In the MAX6866UK33D6S+T, asserting MR low immediately clears the watchdog timer and triggers reset. The reset output remains asserted for the full 1200ms timeout period regardless of whether the cause was VCC drop, MR activation, or WDT expiration. The timer resumes counting only after reset deasserts and WDI receives a valid edge.

Can MAX6866UK33D6S+T drive a 3.3V microprocessor reset pin from a 1.8V supply rail?

Yes-the MAX6866UK33D6S+T's open-drain RESET output allows level-shifting. Connect the external pullup resistor to the 3.3V µP reset rail. When RESET asserts (low), it sinks current from the 3.3V rail; when deasserted, the pullup pulls the line high. This configuration works reliably as long as VCC ≥ 1.2V and sink current requirements are met.

What is the maximum VCC transient duration the MAX6866UK33D6S+T can ignore at 100mV overdrive?

The MAX6866UK33D6S+T is immune to VCC transients ≤40µs in duration when the overdrive magnitude is 100mV above its 3.3V threshold. This immunity is confirmed by the "Maximum VCC Transient Duration vs. Reset Threshold Overdrive" graph in the datasheet, ensuring robust operation in electrically noisy environments like motor-driven handheld tools.