Analog Devices Inc./Maxim Integrated MAX6425UK29+T

Overview

MAX6425UK29+T from Analog Devices is a low-power microprocessor supervisor IC with open-drain active-low reset output, 2.925V ±2.5% factory-trimmed reset threshold, capacitor-adjustable reset timeout (275µs to 5.75ms), and guaranteed operation down to VCC = 1V. It monitors supply voltage in battery-powered embedded controllers and portable equipment.

For engineers reviewing the MAX6425UK29+T datasheet, MAX6425UK29+T pinout, MAX6425UK29+T application, or MAX6425UK29+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 MAX6425UK29+T implements a precision voltage-detection circuit using laser-trimmed resistors to set a 2.925V reset threshold with ±2.5% accuracy over temperature. Its reset assertion is triggered by VCC falling below this threshold, and deassertion is delayed by an externally capacitor-controlled ramp circuit referenced to 0.65V.

Reset timeout is generated by a 240nA internal current source charging the SRT-to-GND capacitor; the time to reach 0.65V determines tRP. The open-drain RESET output requires an external pullup and supports wired-OR configurations with auxiliary reset sources, enabling flexible system-level reset coordination.

Key Specifications

Pinout & Package

MAX6425UK29+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 NC (not internally connected) and may be tied to GND for mechanical stability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP302HS29T1G and TLV803EB29DBZR, the MAX6425UK29+T uniquely combines capacitor-adjustable reset timing, open-drain output, and guaranteed 1V operation-making it optimal for systems requiring configurable reset hold time and multi-rail logic compatibility without sacrificing brownout robustness.

Availability

MAX6425UK29+T is available at Aetrix Electronics and suitable for battery-powered portable equipment, automotive body electronics, and industrial sensor nodes requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6425UK29+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 microprocessor supervision in space-constrained, battery-sensitive applications-emphasizing precision threshold accuracy, flexible timeout control, and robust operation across harsh environmental conditions.

FAQ

What is the exact reset threshold voltage of MAX6425UK29+T?

The MAX6425UK29+T features a factory-laser-trimmed reset threshold of 2.925V with ±1.5% accuracy at +25°C and ±2.5% over the full -40°C to +125°C operating range. This value is confirmed in Table 1 of the datasheet and corresponds to the "29" suffix in the part number.

Can MAX6425UK29+T operate reliably below 1.6V supply voltage?

Yes, the MAX6425UK29+T is fully specified down to VCC = 1.0V and guarantees valid reset output behavior (VOL ≤ 0.4V at ISINK = 3.2mA) even at 1.0V. Its internal circuitry remains functional and the reset assertion/deassertion logic is maintained throughout this range.

How do I calculate the external capacitor value for a 4.0ms reset timeout with MAX6425UK29+T?

Using the formula CSRT = (tRP − 275µs) / 2.735 × 10⁶, a 4.0ms timeout requires CSRT = (0.004 − 0.000275) / 2.735 × 10⁶ = 1362pF. A standard 1300pF or 1500pF ceramic capacitor (low-leakage, X7R or C0G) is recommended for this setting.

Is the NC pin (Pin 3) on MAX6425UK29+T required to be connected?

Pin 3 of MAX6425UK29+T is Not Connected internally and has no electrical function. However, Analog Devices recommends connecting it to GND on the PCB for mechanical stability and improved thermal dissipation-especially in high-vibration environments like automotive applications.

Does MAX6425UK29+T support wired-OR reset configurations?

Yes, the open-drain RESET output of MAX6425UK29+T enables wired-OR reset bus implementation. An external open-drain signal (e.g., from a watchdog timer or manual reset switch) can be directly tied to the RESET pin with a shared pullup resistor, allowing any source to hold the system in reset.