Analog Devices Inc./Maxim Integrated MAX6864UK22D3L+T

Overview

The MAX6864UK22D3L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, integrating voltage monitoring (2.235V reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout). It asserts an active-low push-pull RESET output during VCC brownout, MR assertion, or watchdog timeout, with guaranteed reset validity down to VCC = +1.1V. It targets ultra-low-power portable medical and consumer devices requiring reliable power-on reset and firmware crash recovery.

For engineers reviewing the MAX6864UK22D3L+T datasheet, MAX6864UK22D3L+T pinout, MAX6864UK22D3L+T application, or MAX6864UK22D3L+T equivalent, key selection criteria include its 170nA typical supply current, factory-trimmed 2.235V reset threshold, 300ms minimum reset timeout (D3), 209s watchdog period (L suffix), and SOT23-5 footprint compatibility with TPS383x series.

Technical Context

This device implements a dual-trigger reset architecture: VCC monitoring via precision bandgap reference and hysteresis (±2.5% VTH), plus edge-sensitive watchdog timer clearing on WDI transitions. The internal 10kΩ MR pullup enables direct switch interfacing without external components.

Reset assertion is latched and held for the full D3 timeout (150–300ms) after VCC recovery, MR release, or watchdog expiration. The push-pull RESET output drives low to ≤0.3V at 1.2mA sink (VCC ≥ 2.38V), eliminating need for external pullup resistors.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Compact 2.9mm × 1.6mm footprint with 0.95mm pitch, optimized for space-constrained portable designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3836K33DBVR and MAX6369KA22+T, the MAX6864UK22D3L+T uniquely combines nanopower operation (170nA), precise 2.235V threshold, and long 209s watchdog-enabling multi-year battery life and robust crash recovery in portable medical electronics.

Availability

MAX6864UK22D3L+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, MP3 players, and smart pagers requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6864UK22D3L+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.

The MAX68xx family delivers nanopower supervisory solutions targeting battery-operated medical, portable, and IoT devices where ultra-low ICC and guaranteed reset integrity are critical.

FAQ

What is the exact reset threshold voltage of the MAX6864UK22D3L+T?

The MAX6864UK22D3L+T has a factory-trimmed reset threshold of 2.235V, with ±2.5% tolerance over temperature (-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 MAX6864UK22D3L+T uses this precise threshold to monitor 2.2V system rails reliably.

Does the MAX6864UK22D3L+T require external components for basic operation?

No, the MAX6864UK22D3L+T operates with zero external components: it includes an internal 10kΩ pullup on MR, precision bandgap reference for VTH, and integrated watchdog oscillator. Only a 0.1µF ceramic bypass capacitor on VCC to GND is recommended for noise immunity. The MAX6864UK22D3L+T's push-pull RESET output eliminates need for external pullup resistors.

What does the 'L' suffix in MAX6864UK22D3L+T indicate?

Per Table 3 (Watchdog Timeout), the 'L' suffix in MAX6864UK22D3L+T specifies the long watchdog timeout option: 95–487s, with 209s typical. This distinguishes it from the 'S' (short) option (1.5–7.75s). The MAX6864UK22D3L+T uses this long timeout to supervise infrequently active firmware without requiring frequent WDI toggling.

How does the MAX6864UK22D3L+T ensure reset validity at low supply voltages?

The MAX6864UK22D3L+T guarantees valid RESET assertion down to VCC = +1.1V, verified across -40°C to +85°C. This is achieved through robust internal biasing and output stage design, ensuring deterministic reset behavior during deep brownout-critical for Li-ion cells discharging below 2.5V. The MAX6864UK22D3L+T maintains this specification without external circuitry.

What is the function of Pin 4 (WDI) on the MAX6864UK22D3L+T?

Pin 4 (WDI) is the watchdog input of the MAX6864UK22D3L+T. It monitors µP activity: if WDI remains static (high or low) longer than the 209s typical timeout, the internal watchdog expires and asserts RESET for the D3 period (150–300ms). The timer clears on any rising or falling edge, supporting pulse widths ≥150ns. This function is exclusive to MAX6864–MAX6869 variants.