Analog Devices Inc./Maxim Integrated MAX6866UK41D3S+T

Overview

The MAX6866UK41D3S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 4.100V reset threshold (±2.5%), 300ms minimum reset timeout, and integrated watchdog timer with 3.3s typical timeout. It monitors VCC, responds to manual reset (MR), and asserts an active-low open-drain RESET output - ideal for battery-powered glucose monitors and portable medical devices requiring reliable brownout protection.

For engineers reviewing the MAX6866UK41D3S+T datasheet, MAX6866UK41D3S+T pinout, MAX6866UK41D3S+T application, or MAX6866UK41D3S+T equivalent, key selection criteria include its 4.100V reset threshold tolerance, 300ms reset timeout stability over temperature, watchdog immunity to short VCC transients, and guaranteed RESET validity down to VCC = +1.1V - all critical for low-voltage, long-life embedded systems.

Technical Context

This device integrates three core functions: precision voltage monitoring with hysteresis (0.5% of VTH), a manual reset input with 250ns MR-to-reset delay and 200ns glitch rejection, and a watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 3.3s (typ). Its BiCMOS process enables stable operation across –40°C to +85°C.

The open-drain RESET output supports level-shifting up to 5.5V and requires no external components; internal 10kΩ MR pullup eliminates need for external biasing. Immunity to VCC transients ≤40µs at 100mV overdrive ensures robustness in noisy power environments.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact 2.9mm × 1.6mm footprint with 0.95mm height - optimized 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 MAX6866UK41D3S+T, MAX6326UR29D3+T omits watchdog capability and targets lower-voltage rails, while TPS3839G33DBVR trades nanopower efficiency and open-drain versatility for lower unit cost - making MAX6866UK41D3S+T the sole choice for 4.1V brownout + watchdog co-supervision in medical wearables.

Availability

MAX6866UK41D3S+T is available at Aetrix Electronics and suitable for glucose monitors, portable ECG devices, and wireless pulse oximeters requiring stable component supply with guaranteed long-term manufacturability and lead-free compliance.

Supply support for MAX6866UK41D3S+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 demanding applications in industrial, medical, and communications markets.

The MAX6854–MAX6869 family delivers nanopower supervisory functionality specifically for battery-operated medical and portable electronics, emphasizing ultra-low ICC, wide VCC range, and integrated watchdog reliability.

FAQ

What is the exact reset threshold voltage of the MAX6866UK41D3S+T?

The MAX6866UK41D3S+T has a factory-trimmed reset threshold of 4.100V 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 "41" corresponds to 4.100V nominal. The hysteresis is 0.5% of VTH, ensuring clean release without chatter during slow VCC rise.

Does the MAX6866UK41D3S+T support open-drain reset output?

Yes, the MAX6866UK41D3S+T provides an active-low open-drain RESET output on Pin 1. It requires an external pullup resistor to the target logic rail (e.g., 3.3V or 5V) and can sink ≥50µA at VCC ≥1.1V. This configuration enables level-shifting and wired-OR reset bus architectures common in multi-rail systems.

What is the watchdog timeout period for the MAX6866UK41D3S+T?

The MAX6866UK41D3S+T features a watchdog timeout period of 3.3s typical (minimum 1.5s, maximum 7.75s), denoted by the "S" suffix in the part number. The timer clears on any rising or falling edge at WDI (Pin 4) and expires only if WDI remains static beyond this interval - critical for detecting firmware hangs in safety-critical medical firmware.

Can the MAX6866UK41D3S+T operate down to 1.2V supply voltage?

Yes, the MAX6866UK41D3S+T operates across VCC = 1.2V to 5.5V and guarantees valid RESET assertion down to VCC = +1.1V. At 1.2V, its supply current is 190nA (typ), and RESET output low voltage remains ≤0.3V with 50µA sink load - enabling reliable supervision of ultra-low-voltage microcontrollers and sensors.

Is the MAX6866UK41D3S+T pin-compatible with other devices in the MAX68xx family?

The MAX6866UK41D3S+T uses the standard 5-pin SOT23-5 pinout shared across MAX6864–MAX6869 variants (Pin 1: RESET, Pin 2: GND, Pin 3: MR, Pin 4: WDI, Pin 5: VCC). This allows drop-in replacement among SOT23-packaged members with identical WDI and MR functionality - though reset threshold and timeout values differ by suffix.