Analog Devices Inc./Maxim Integrated MAX6864UK18D3S+T

Overview

The MAX6864UK18D3S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring voltage monitoring (1.8V reset threshold), manual reset input (MR), and watchdog timer with 3.3s typical timeout. It asserts an active-low push-pull RESET output during VCC brownout, MR assertion, or watchdog expiration, and guarantees valid reset down to VCC = +1.1V. It targets ultra-low-power portable systems such as glucose monitors and battery-powered medical devices.

For engineers reviewing the MAX6864UK18D3S+T datasheet, MAX6864UK18D3S+T pinout, MAX6864UK18D3S+T application, or MAX6864UK18D3S+T equivalent, key selection criteria include its 170nA typical supply current, factory-trimmed 1.8V reset threshold, 300ms minimum reset timeout, watchdog input (WDI) compatibility, and guaranteed operation across –40°C to +85°C.

Technical Context

This device integrates three core supervisory functions: precision voltage monitoring with ±2.5% threshold accuracy, a glitch-immune manual reset input with 250ns MR-to-reset delay and internal 10kΩ pullup, and a watchdog timer that clears on any WDI edge and expires if WDI remains static beyond 3.3s (typ). The reset output remains asserted for ≥300ms after VCC recovery, MR deassertion, or watchdog timeout.

The MAX6864UK18D3S+T uses BiCMOS process technology and operates from 1.2V to 5.5V supply. Its reset logic is immune to short VCC transients (e.g., ≤40µs at 100mV overdrive), and it maintains valid RESET output down to VCC = +1.1V - critical for reliable power-down sequencing in low-voltage embedded systems.

Key Specifications

Pinout & Package

MAX6864UK18D3S+T is housed in a lead-free 5-pin SOT23-5 package (JEDEC MO-178AA), with 1.3mm height and 2.9mm × 1.6mm footprint - suitable for space-constrained PCB layouts in handheld diagnostics equipment.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK18D3S+T, the MAX6864UK18D3S+T offers native active-low reset compatibility with most µPs; compared with TPS3836K33DBVR, it delivers 170nA operation and 1.8V threshold accuracy essential for modern low-voltage wearables - making it the optimal choice for power-critical 1.8V medical and portable designs.

Availability

MAX6864UK18D3S+T is available at Aetrix Electronics and suitable for glucose monitoring systems, patient vital sign monitors, industrial handheld scanners, and wearable health trackers requiring stable component supply across extended production lifecycles.

Supply support for MAX6864UK18D3S+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 communications applications.

The MAX6864UK18D3S+T belongs to Maxim's nanopower µP supervisory family, designed specifically for battery-powered portable medical and consumer electronics where ultra-low quiescent current and precise low-voltage monitoring are mandatory.

FAQ

What is the exact reset threshold voltage of the MAX6864UK18D3S+T?

The MAX6864UK18D3S+T has a factory-trimmed reset threshold of 1.8V, with guaranteed tolerance of ±2.5% over the full temperature range (–40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "18" corresponds to 1.755V (min), 1.800V (typ), and 1.845V (max). The 1.8V threshold ensures precise supervision of 1.8V logic rails without external calibration.

Does the MAX6864UK18D3S+T require external components for basic operation?

No, the MAX6864UK18D3S+T requires no external components for core functionality. A 0.1µF ceramic bypass capacitor on VCC is recommended for noise immunity but not strictly required for DC operation. The MR input has an internal 10kΩ pullup, and the push-pull RESET output needs no external pullup. Only optional noise filtering (e.g., 0.1µF on MR) is suggested for harsh EMI environments.

What is the watchdog timeout behavior of the MAX6864UK18D3S+T?

The MAX6864UK18D3S+T features a watchdog timer with a typical timeout of 3.3s (S-suffix), with min/max of 1.5s/7.75s. The timer clears on any rising or falling edge at WDI and expires only if WDI remains static (high or low) beyond the timeout. During reset assertion, the watchdog is paused and resumes counting immediately upon reset deassertion - ensuring deterministic recovery from firmware hangs.

Can the MAX6864UK18D3S+T operate reliably at VCC = 1.2V?

Yes, the MAX6864UK18D3S+T is fully specified to operate from VCC = 1.2V to 5.5V. Its supply current remains at 170nA (typ) at 1.8V and increases only modestly at lower voltages. Crucially, the RESET output is guaranteed valid down to VCC = +1.1V, meaning the device continues asserting reset correctly even as the supply collapses - a key reliability feature for brownout recovery.

Is the MAX6864UK18D3S+T pin-compatible with other devices in the MAX68xx family?

The MAX6864UK18D3S+T shares the same 5-pin SOT23-5 pinout as MAX6864/MAX6865/MAX6866 variants (Pin 1: RESET, Pin 2: GND, Pin 3: MR, Pin 4: WDI, Pin 5: VCC). It is not pin-compatible with MAX6861–MAX6863 (which use CT instead of WDI on Pin 4) or MAX6854–MAX6856 (which lack WDI entirely). Always verify pin function alignment using the Selector Guide before substitution.