Analog Devices Inc./Maxim Integrated MAX6418UK22+

Overview

MAX6418UK22+ from Maxim Integrated is a low-power, dual-voltage microprocessor reset supervisor IC with one factory-trimmed VCC reset threshold (2.188V typical) and one adjustable RESET IN input for monitoring secondary voltages down to 1.26V. It features an active-low push-pull RESET output, capacitor-adjustable reset timeout delay (275µs base + 2.71×10⁶ × CSRT), and operates across -40°C to +125°C in a SOT23-5 package. It is used in automotive ECUs and battery-powered controllers requiring reliable dual-rail brownout detection.

For engineers reviewing the MAX6418UK22+ datasheet, MAX6418UK22+ pinout, MAX6418UK22+ application, or MAX6418UK22+ equivalent, key selection criteria include its dual-threshold architecture, 1.7µA quiescent current, guaranteed RESET validity down to VCC = 1V, SRT capacitor-based timeout tuning, and automotive-grade temperature range.

Technical Context

The MAX6418UK22+ integrates two independent reset comparators: one laser-trimmed VCC monitor with ±2.5% threshold accuracy over temperature and a high-impedance RESET IN comparator referenced to 1.26V with ±1.25% accuracy. Reset assertion occurs if either VCC falls below 2.188V or RESET IN falls below its externally set threshold (e.g., via resistor divider).

Reset deassertion timing is controlled by an internal 240nA current source charging an external capacitor on the SRT pin to a 0.65V ramp threshold; the resulting timeout is programmable from ~275µs to >100ms. The active-low push-pull RESET output drives logic-compatible loads with VOL ≤ 0.4V at 3.2mA sink and VOH ≥ 0.8×VCC at 800µA source.

Key Specifications

Pinout & Package

SOT23-5 package: 2.9mm × 1.6mm × 1.1mm body, gull-wing leads, RoHS-compliant lead-free finish (+ suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6419UK22+, MAX6418UK22+ provides native compatibility with industry-standard active-low µP reset inputs; compared with TLV809E22DBVR, it delivers essential dual-voltage supervision and field-tunable timeout - critical for complex embedded systems requiring layered power integrity.

Availability

MAX6418UK22+ is available at Aetrix Electronics and suitable for automotive electronics, medical instrumentation, and industrial control systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6418UK22+ 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, mixed-signal, and power management ICs for demanding industrial, automotive, and medical applications.

The MAX6412–MAX6420 product line delivers ultra-low-power, configurable reset supervision for systems requiring dual-rail monitoring, programmable timeout, and operation across harsh environmental conditions.

FAQ

What is the exact VCC reset threshold voltage for MAX6418UK22+?

The MAX6418UK22+ has a factory-trimmed VCC reset threshold of 2.188V (typical), with a guaranteed range of 2.133V to 2.243V at TA = -40°C to +125°C per Table 1 and Electrical Characteristics. This value is laser-trimmed and does not require external calibration. The "22" suffix in MAX6418UK22+ directly references this 2.188V nominal threshold.

Does MAX6418UK22+ include a manual reset (MR) input?

No, MAX6418UK22+ does not include a functional manual reset input. Per the Selector Guide and Pin Description table, MR is marked as "-" (not present) for MAX6418/MAX6419/MAX6420 devices. Pin 4 is a no-connect; the device relies solely on VCC and RESET IN monitoring and SRT-controlled timeout. This distinguishes it from MAX6412–MAX6414 variants which feature MR.

How do I calculate the SRT capacitor value for a 50ms reset timeout with MAX6418UK22+?

Use the formula tRP = (2.71 × 10⁶) × CSRT + 275µs. For tRP = 50ms (0.05s), rearrange to CSRT = (0.05 − 0.000275) / 2.71×10⁶ = 18.3nF. Select a low-leakage ceramic capacitor (e.g., X7R, ≤10nA leakage); a 18nF or 22nF standard value yields 49.2ms or 59.9ms timeout respectively. Verify with oscilloscope on RESET during VCC ramp.

Can MAX6418UK22+ monitor a 1.8V supply using the RESET IN pin?

Yes. Configure a resistor divider between the 1.8V rail and GND such that the voltage at RESET IN equals 1.26V when the rail is at its nominal 1.8V. Using R2 = 1MΩ, calculate R1 = 1MΩ × (1.8V / 1.26V − 1) ≈ 429kΩ. The MAX6418UK22+ RESET IN comparator triggers when this divided voltage falls below 1.26V, providing accurate 1.8V undervoltage detection.

What is the maximum recommended PCB trace length for the SRT pin on MAX6418UK22+?

Maxim recommends keeping the SRT trace as short as possible - ideally under 2mm - due to its sensitivity to stray capacitance and leakage currents. Long traces introduce timing error in the reset timeout period. Avoid routing near high-speed signals or high-voltage nodes. Use guard rings and ground planes adjacent to the SRT trace, and never probe this node directly with a scope tip during evaluation.