Analog Devices Inc./Maxim Integrated MAX6425UK24+T

Overview

MAX6425UK24+T from Analog Devices is a low-power microprocessor supervisor IC with open-drain active-low reset output, 2.4V ±2.5% factory-trimmed reset threshold, capacitor-adjustable reset timeout (3.0–5.75ms with 1500pF), and guaranteed operation down to VCC = 1V. It monitors supply voltage in portable and battery-powered systems to prevent erroneous µP execution during brownout.

For engineers reviewing the MAX6425UK24+T datasheet, MAX6425UK24+T pinout, MAX6425UK24+T application, or MAX6425UK24+T equivalent, key selection factors include its 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

The MAX6425UK24+T implements a precision voltage detector using laser-trimmed resistors to set its 2.4V reset threshold with ±2.5% accuracy over temperature. Its reset assertion is triggered by VCC falling below this threshold, with hysteresis of 4×VTH (9.6mV) to prevent chatter.

Reset deassertion timing is controlled by an internal 240nA current source charging an external capacitor (CSRT) connected to the SRT pin; the voltage ramp to 0.65V determines the timeout period. The open-drain RESET output requires an external pullup resistor (10kΩ–100kΩ) and supports logic-level translation across supplies up to 5.5V.

Key Specifications

Pinout & Package

MAX6425UK24+T is housed in a 5-pin SOT23-5 package (package code U5+2, outline 21-0057), with 1.3mm × 2.9mm footprint and 0.95mm height. Pin 1 is VCC, Pin 2 is GND, Pin 3 is SRT, Pin 4 is RESET, and Pin 5 is NC (not internally connected).

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP302HS24T1G and MC33064DR2G, MAX6425UK24+T uniquely delivers capacitor-tunable reset timeout within the 2.4V threshold class-enabling precise alignment with µP reset timing requirements without sacrificing low IQ or open-drain flexibility.

Availability

MAX6425UK24+T is available at Aetrix Electronics and suitable for portable medical monitors, battery-powered industrial sensors, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6425UK24+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 MAX6421–MAX6426 family was designed specifically for ultra-low-power, precision voltage monitoring in space-constrained battery-operated and automotive systems-emphasizing quiescent current minimization, wide temperature operation, and flexible reset timing.

FAQ

What is the exact reset threshold voltage of MAX6425UK24+T and how is it trimmed?

The MAX6425UK24+T features a factory-laser-trimmed reset threshold of 2.400V with ±2.5% accuracy over the full -40°C to +125°C temperature range. This value is permanently programmed during wafer test using precision resistor trimming, eliminating the need for external calibration. The "24" suffix in MAX6425UK24+T explicitly denotes the 2.4V nominal threshold per Table 1 in the datasheet, and the device maintains guaranteed performance without user adjustment.

Can MAX6425UK24+T operate reliably when VCC drops below 2.4V but remains above 1.0V?

Yes, MAX6425UK24+T guarantees valid reset output functionality down to VCC = 1.0V. When VCC falls below the 2.4V threshold, the open-drain RESET pin actively pulls low (VOL ≤ 0.3V at ISINK = 500µA). Even as VCC declines further-to 1.0V-the device continues asserting reset correctly, ensuring the connected microprocessor remains held in reset until power recovers or fails completely.

How do I calculate the external capacitor value needed for a specific reset timeout with MAX6425UK24+T?

Use the formula CSRT = (tRP − 275µs) / 2.735 × 10⁶, where tRP is your desired timeout in seconds and CSRT is the capacitor value in farads. For example, to achieve 4.375ms: CSRT = (0.004375 − 0.000275) / 2,735,000 = 1500pF. Ceramic capacitors with <10nA leakage are recommended; avoid electrolytics or high-leakage dielectrics that distort timing.

Is the NC pin (Pin 5) on MAX6425UK24+T required to be grounded or left floating?

Pin 5 of MAX6425UK24+T is designated NC (Not Connected) and has no internal circuit connection. It may be safely left floating or tied to GND-neither choice affects device operation, timing accuracy, or reliability. No current flows into or out of this pin, and grounding it introduces no benefit or risk; PCB layout best practice is to omit copper connection unless needed for mechanical stability.

Does MAX6425UK24+T support wired-OR reset configurations with other open-drain supervisors?

Yes, MAX6425UK24+T's open-drain RESET output enables direct wired-OR implementation. Connect its RESET pin to the same net as other open-drain reset sources (e.g., watchdog timers or manual reset buttons), using a single shared pullup resistor. The system resets whenever any device pulls the line low-providing fail-safe redundancy without additional logic. Ensure total sink current stays within 3.2mA (max) at VCC ≥ 4.5V.