Analog Devices Inc./Maxim Integrated MAX6418UK23+

Overview

MAX6418UK23+ from Maxim Integrated is a low-power, dual-voltage microprocessor reset supervisor IC with one factory-trimmed VCC reset threshold (2.313V 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 and battery-powered embedded controllers requiring reliable dual-rail brownout detection.

For engineers reviewing the MAX6418UK23+ datasheet, MAX6418UK23+ pinout, MAX6418UK23+ application, or MAX6418UK23+ equivalent, key selection criteria include its dual-threshold architecture, 1.7µA quiescent current, guaranteed RESET validity down to VCC = 1V, and SRT capacitor-based timeout programming - critical for deterministic µP initialization in safety-critical power-up sequences.

Technical Context

The MAX6418UK23+ integrates two independent voltage comparators: one laser-trimmed internal reference for VCC monitoring at 2.313V (±2.5% over temperature), and a high-impedance RESET IN comparator with 1.26V threshold for externally scaled voltages via resistor divider. Reset assertion occurs if either input falls below its threshold or MR is asserted (though MR is not present on MAX6418 variants).

Its reset timeout is generated by a precision 240nA current source charging an external capacitor (SRT-to-GND), with reset deassertion triggered when the ramp voltage reaches 0.65V. The active-low push-pull RESET output drives logic-compatible loads with VOL ≤ 0.4V at 3.2mA sink, supporting direct interface to µP reset inputs without pull-up resistors.

Key Specifications

Pinout & Package

SOT23-5 package: ultra-compact 2.9mm × 1.6mm footprint with 0.95mm pitch, optimized for space-constrained PCBs in portable and automotive modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6418UK23+, MAX6316LUK23+T offers lower current but forfeits dual-rail monitoring, while TPS3808G125DBVR trades adjustability and push-pull drive for ultra-low current and fixed long timeout - making MAX6418UK23+ uniquely suited for compact, dual-supply systems needing programmable timing and direct µP interface.

Availability

MAX6418UK23+ is available at Aetrix Electronics and suitable for automotive body control modules, portable medical devices, industrial PLC I/O, smart energy meters, and battery-powered embedded controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6418UK23+ 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 configurable, ultra-low-power reset supervision for systems with multiple voltage domains - specifically engineered to replace discrete reset solutions in safety-critical embedded platforms.

FAQ

What is the exact VCC reset threshold voltage for MAX6418UK23+?

The MAX6418UK23+ has a factory-trimmed VCC reset threshold of 2.313V (typical), with ±2.5% tolerance over the full -40°C to +125°C operating range. This value corresponds to the "23" suffix in the part number per Table 1 of the datasheet, and is laser-trimmed for accuracy without requiring external calibration. The threshold is referenced internally and does not depend on external components.

Does MAX6418UK23+ include a manual reset (MR) input?

No, the MAX6418UK23+ does not include a manual reset (MR) input. Per the Selector Guide and Pin Description tables, MR is only present on MAX6412/MAX6413/MAX6414 variants. The MAX6418 series provides dual-voltage monitoring (fixed VCC + adjustable RESET IN) but omits MR to optimize die size and cost for applications where external reset initiation is handled separately.

How do I calculate the reset timeout period for MAX6418UK23+?

The reset timeout period (tRP) for MAX6418UK23+ is calculated using tRP = (2.71 × 10⁶) × CSRT + 275µs, where tRP is in seconds and CSRT is the capacitor value in farads. For example, a 1500pF capacitor yields tRP ≈ 4.375ms. CSRT must be low-leakage (<10nA), and ceramic capacitors are recommended. The SRT pin must be connected directly to this capacitor with minimal trace length to avoid timing errors.

Can MAX6418UK23+ monitor a 3.3V supply on its RESET IN pin?

Yes, MAX6418UK23+ can monitor a 3.3V supply using its RESET IN pin by connecting it through an external resistor divider. Since the internal RESET IN threshold is fixed at 1.26V, use R1 and R2 such that VMON_TH = 1.26V × (R1 + R2)/R2 = 3.3V. With R2 = 1MΩ, R1 calculates to ~1.62MΩ. This configuration allows precise 3.3V rail supervision while maintaining ultra-low current draw due to the high-impedance input.

What is the function of the SRT pin on MAX6418UK23+?

The SRT pin on MAX6418UK23+ is the Set Reset Timeout input, which connects to an external capacitor to program the reset assertion duration. It sources a precision 240nA current that charges the capacitor; reset deassertion occurs when the capacitor voltage ramps to 0.65V. Layout best practices require short, isolated traces to SRT to prevent stray capacitance or leakage from altering the timeout - critical for achieving accurate, repeatable reset timing in production systems.