Analog Devices Inc./Maxim Integrated MAX6426UK22+T

Overview

MAX6426UK22+T from Analog Devices is a low-power microprocessor supervisor IC with open-drain active-low reset output, 2.188V ±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 medical instruments to prevent erroneous code execution during brownout.

For engineers reviewing the MAX6426UK22+T datasheet, MAX6426UK22+T pinout, MAX6426UK22+T application, or MAX6426UK22+T equivalent, key selection criteria include its SOT23-5 open-drain reset output, 1.6µA typical quiescent current, -40°C to +125°C operating range, and compatibility with multi-supply logic interfacing via external pullup.

Technical Context

The MAX6426UK22+T implements a precision voltage-detection architecture using laser-trimmed resistors to set its 2.188V 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 adjustable timeout determined by a 240nA ramp current charging a capacitor on the SRT pin to a 0.65V internal reference.

As an open-drain device, MAX6426UK22+T requires an external pullup resistor (10kΩ–100kΩ) to a logic supply up to 5.5V, enabling wired-OR reset capability and voltage-level translation across mixed-supply systems. It guarantees valid reset signaling down to VCC = 1V but is not specified for operation below that voltage.

Key Specifications

Pinout & Package

MAX6426UK22+T is housed in a 5-pin SOT23-5 package (package code U5+2), RoHS-compliant, tape-and-reel format. Pin 1 is VCC, Pin 2 is GND, Pin 3 is SRT (reset timeout capacitor input), Pin 4 is RESET (open-drain active-low output), and Pin 5 is NC (not internally connected).

Key Features

Applications

Equivalent & Alternatives

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

Compared with PST9222 and NCP302LSN22T1G, MAX6426UK22+T offers the lowest quiescent current (1.6µA), fully adjustable timeout, and verified suitability for automotive and medical use cases-making it optimal for high-reliability, battery-sensitive designs demanding timing precision.

Availability

MAX6426UK22+T is available at Aetrix Electronics and suitable for battery-powered medical sensors, automotive body control modules, and industrial programmable logic controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6426UK22+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 delivers ultra-low-power, precision voltage supervision for mission-critical embedded systems where reliability under brownout and transient conditions is non-negotiable.

FAQ

What is the exact reset threshold voltage of MAX6426UK22+T and how accurate is it over temperature?

The MAX6426UK22+T has a factory-laser-trimmed reset threshold of 2.188V, with accuracy of ±1.5% at +25°C and ±2.5% over the full -40°C to +125°C operating range. This specification is confirmed in the Electrical Characteristics table of the official Analog Devices datasheet, ensuring robust brownout detection across automotive and industrial environments where supply rails may drift significantly with temperature.

Does MAX6426UK22+T support operation down to VCC = 0V, and what happens below 1V?

MAX6426UK22+T guarantees valid reset output only down to VCC = 1V; below that, RESET output current-sinking capability declines drastically and logic state becomes indeterminate. The datasheet explicitly states open-drain RESET versions like MAX6426UK22+T are not recommended for applications requiring valid logic down to 0V. For such cases, a pulldown resistor to ground is suggested-but MAX6426UK22+T itself does not ensure functionality below 1V.

How is the reset timeout period set on MAX6426UK22+T, and what capacitor value gives a 4.375ms delay?

The reset timeout on MAX6426UK22+T is set by connecting a capacitor (CSRT) between the SRT pin and GND. Using the formula tRP = 2.73 × 10⁶ × CSRT + 275µs, a 4.375ms timeout corresponds to CSRT ≈ 1500pF. This value is confirmed in the datasheet's Electrical Characteristics table under "Reset Timeout Period" with CSRT = 1500pF, and is validated across temperature in Typical Operating Characteristics plots.

Can MAX6426UK22+T interface with a 1.8V microcontroller while powered from a 3.3V supply?

Yes. MAX6426UK22+T's open-drain RESET output allows direct interface with 1.8V logic: connect the external pullup resistor to the 1.8V supply rail instead of the 3.3V VCC. The datasheet confirms RESET can be pulled to "any supply from 0 to 5.5V", and VOH specifications guarantee valid high-level output when sourcing 1µA into the 1.8V domain-enabling seamless voltage-level translation without additional components.

Is MAX6426UK22+T pin-compatible with other members of the MAX642x family, and which ones share the same SOT23-5 footprint?

MAX6426UK22+T shares the identical 5-pin SOT23-5 package and pinout with MAX6340, MAX6424, MAX6425, and other MAX6426 variants (e.g., MAX6426UK26+T). All have VCC–GND–SRT–RESET–NC pin order. However, output type differs: MAX6424 is push-pull, while MAX6426UK22+T is open-drain-so direct substitution requires verifying reset output drive requirements in the target system.