Analog Devices Inc./Maxim Integrated MAX6418UK26+T

Overview

MAX6418UK26+T from Maxim Integrated is a low-power dual-voltage microprocessor supervisor IC with one factory-trimmed VCC reset threshold (2.625V ±2.5%) and one adjustable RESET IN input (1.26V threshold) for monitoring secondary supply rails. It features an active-low push-pull RESET output, capacitor-adjustable reset timeout (275µs to 5.75ms), manual reset capability via MR pin, and operates across -40°C to +125°C in automotive-grade SOT23-5 packaging. It is used in battery-powered controllers and critical μP monitoring where dual-rail validity must be enforced before system boot.

For engineers reviewing the MAX6418UK26+T datasheet, MAX6418UK26+T pinout, MAX6418UK26+T application, or MAX6418UK26+T equivalent, key selection considerations include its dual-threshold architecture, guaranteed RESET validity down to VCC = 1V, 1.7µA typical quiescent current at 1.8V, and AEC-Q100 qualification for automotive use cases requiring robust brownout immunity and transient rejection.

Technical Context

The MAX6418UK26+T integrates two independent voltage monitoring paths: a laser-trimmed bandgap reference sets the fixed 2.625V VCC threshold, while a high-impedance comparator monitors RESET IN against a precise 1.26V internal reference - enabling external resistor-divider configuration for custom VMON_TH thresholds. Reset assertion occurs if either monitored rail falls below its respective threshold or MR is pulled low.

Reset deassertion is controlled by an internal 240nA current source charging an external capacitor on SRT; the resulting ramp-to-0.65V timing defines the timeout period (tRP = 2.71×10⁶ × CSRT + 275µs). The active-low push-pull RESET output drives logic-compatible levels across VCC = 1.0V–5.5V with VOL ≤ 0.4V at 3.2mA sink, ensuring reliable μP reset signaling under varying supply conditions.

Key Specifications

Pinout & Package

SOT23-5 package (U5+2A outline, RoHS-compliant, 5-pin surface-mount) with thermal resistance θJA = 255.9°C/W on multilayer board.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-threshold supervisor applications.

Compared with MAX6418UK26+T, the leaded MAX6418UK26-T shares identical electrical behavior but lacks RoHS compliance, while TPS3808G26DBVR offers comparable fixed-threshold performance but omits the adjustable RESET IN feature essential for flexible dual-rail validation.

Availability

MAX6418UK26+T is available at Aetrix Electronics and suitable for automotive engine control units, medical infusion pump controllers, and industrial PLC I/O modules requiring stable component supply with AEC-Q100 assurance and extended temperature support.

Supply support for MAX6418UK26+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 demanding industrial, automotive, and medical applications.

The MAX6412–MAX6420 product line delivers ultra-low-power, capacitor-programmable reset supervision for systems requiring dual-voltage validation and brownout immunity across extreme temperatures.

FAQ

What is the exact VCC reset threshold voltage for MAX6418UK26+T?

The MAX6418UK26+T has a factory-laser-trimmed VCC reset threshold of 2.625V, with ±2.5% tolerance over the full -40°C to +125°C operating range. This value is confirmed in the Electrical Characteristics table under "VCC Reset Threshold Accuracy" and corresponds to the "26" suffix per Table 1 in the datasheet. The threshold remains stable due to on-chip bandgap referencing and laser trimming during production.

Does MAX6418UK26+T support monitoring a secondary voltage lower than 1.26V?

No, MAX6418UK26+T does not support monitoring voltages below 1.26V on the RESET IN pin. Its internal comparator references a fixed 1.26V threshold, and the datasheet specifies VRST falling threshold as 1.205V to 1.305V. To monitor lower voltages, an external level-shifting circuit would be required - but this is outside the specified operating conditions and not supported by the device's design or characterization.

How do I calculate the external capacitor value for a 4ms reset timeout with MAX6418UK26+T?

Use the formula CSRT = (tRP − 275µs) / 2.71×10⁶, where tRP = 4ms = 0.004s. Substituting gives CSRT = (0.004 − 0.000275) / 2.71×10⁶ ≈ 1375pF. A standard 1500pF ceramic capacitor yields tRP = 4.375ms (within datasheet limits), and the MAX6418UK26+T's SRT pin requires low-leakage (<10nA) dielectric - X7R or C0G types are recommended.

Is MAX6418UK26+T pin-compatible with other MAX6418 variants like MAX6418UK22+T?

Yes, MAX6418UK26+T is pin-compatible with all MAX6418 variants (e.g., MAX6418UK22+T, MAX6418UK46+T) because they share identical SOT23-5 packaging, pinout, and functional architecture. Only the factory-trimmed VCC threshold differs (2.625V vs. 2.188V or 4.625V); all other electrical characteristics, timing, and interface behavior remain consistent across the MAX6418 family.

Can MAX6418UK26+T operate reliably at VCC = 1.2V?

Yes, MAX6418UK26+T is fully specified to operate at VCC = 1.0V, including guaranteed RESET output validity (VOL ≤ 0.3V at 500µA sink) and functional reset assertion/deassertion. At 1.2V, supply current is ~1.8µA (per ICC vs. VCC curve), and the 2.625V VCC threshold monitoring remains active - though VCC must rise above that threshold to release reset. This makes it suitable for deep-brownout recovery in energy-harvesting or backup-power systems.