Analog Devices Inc./Maxim Integrated MAX6425UK30+T

Overview

The MAX6425UK30+T from Analog Devices is a low-power microprocessor supervisor IC with open-drain active-low reset output, 3.0V factory-trimmed reset threshold (±2.5% over temperature), capacitor-adjustable reset timeout (3.0–5.75ms with 1500pF), and guaranteed operation down to VCC = 1V. It monitors supply voltage in battery-powered embedded controllers and portable equipment to prevent code-execution errors during brownout or power-up.

For engineers reviewing the MAX6425UK30+T datasheet, MAX6425UK30+T pinout, MAX6425UK30+T application, or MAX6425UK30+T equivalent, key selection criteria include its 5-pin SOT23-5 open-drain reset architecture, 1.6µA typical quiescent current, -40°C to +125°C operating range, and compatibility with multi-rail logic interfacing via external pullup.

Technical Context

This device implements a precision voltage-detection circuit with laser-trimmed internal resistors to set the 3.0V reset threshold, coupled with a 240nA constant-current ramp source charging an external capacitor on the SRT pin. Reset assertion occurs when VCC falls below the threshold; deassertion requires both VCC rise above threshold and capacitor voltage ramping to 0.65V.

The open-drain RESET output supports wired-OR configurations and logic-level translation across supplies from 0V to 5.5V using an external pullup resistor (10kΩ–100kΩ). Immunity to short VCC transients (<50µs for 100mV overdrive) is achieved via internal hysteresis and timing control, not digital filtering.

Key Specifications

Pinout & Package

MAX6425UK30+T is housed in a 5-pin SOT23-5 package (package code U5+2, outline 21-0057), with exposed pad not electrically connected. Pin 3 is internally unconnected (N.C.) and must be left floating or tied to GND per layout best practice.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP302LSN30T1G and TLV809EC29DBVR, the MAX6425UK30+T provides design flexibility through user-adjustable reset timeout and proven immunity to short VCC transients-critical for automotive and industrial systems where supply noise is inherent and boot timing is tightly constrained.

Availability

MAX6425UK30+T is available at Aetrix Electronics and suitable for battery-powered portable instrumentation, automotive body control modules, and industrial PLC I/O modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6425UK30+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

Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The MAX6425UK30+T belongs to the MAX6340/MAX6421–MAX6426 family of low-power µP supervisors designed specifically for robust, capacitor-programmable reset generation in space-constrained, battery-sensitive, and thermally demanding applications.

FAQ

What is the exact reset threshold voltage tolerance for MAX6425UK30+T over temperature?

The MAX6425UK30+T has a nominal reset threshold of 3.000V with ±2.5% tolerance over the full operating temperature range of -40°C to +125°C. At +25°C, the tolerance tightens to ±1.5%. This specification is guaranteed by laser trimming during manufacturing and confirmed in the Electrical Characteristics table of the official Analog Devices datasheet (Rev 11, 9/24).

Can MAX6425UK30+T operate reliably when VCC drops below 1.6V?

Yes - the MAX6425UK30+T is fully specified to operate and assert valid RESET down to VCC = 1.0V. Its internal comparator and bias circuitry remain functional at 1V, and the open-drain RESET output maintains sink capability (VOL ≤ 0.4V at ISINK = 3.2mA) even at this level. This ensures deterministic reset behavior during deep brownout events where many µPs stall.

How do I calculate the SRT capacitor value for a 4.0ms reset timeout with MAX6425UK30+T?

Use the formula CSRT = (tRP − 275µs) / 2.735 × 10⁶, where tRP = 4.0ms = 0.004s. Substituting gives CSRT ≈ (0.004 − 0.000275) / 2,735,000 ≈ 1362pF. A standard 1300pF or 1500pF ceramic capacitor (low-leakage, X7R/C0G) meets this requirement and yields 3.9–4.4ms timeout per the Typical Operating Characteristics graph.

Is the N.C. pin (Pin 3) on MAX6425UK30+T required to be grounded?

No - Pin 3 is Not Connected internally and has no electrical function. Analog Devices' datasheet states it "can be connected to GND" for mechanical stability but does not require grounding. Leaving it floating is acceptable; tying it to GND introduces no risk and may improve board-level EMI resilience in high-noise environments.

Does MAX6425UK30+T support wired-OR reset configuration with external logic signals?

Yes - the open-drain RESET output of MAX6425UK30+T enables wired-OR functionality. An external open-drain signal (e.g., from a watchdog timer or fault monitor) can be directly connected to the same RESET net, pulling it low to hold the µP in reset. The MAX6425UK30+T will not interfere, though timeout timing applies only to its own VCC-based reset assertion.