Analog Devices Inc./Maxim Integrated MAX6424UK22

Overview

MAX6424UK22 from Maxim Integrated is a low-power microprocessor supervisor IC that monitors 2.188V system supply voltage and asserts an active-low push-pull reset signal during undervoltage conditions. It features capacitor-adjustable reset timeout (275µs to 5.75ms), guaranteed operation down to VCC = 1V, and 1.6µA typical quiescent current. It is used in battery-powered controllers to prevent code execution errors during power-up and brownout.

For engineers reviewing the MAX6424UK22 datasheet, MAX6424UK22 pinout, MAX6424UK22 application, or MAX6424UK22 equivalent, key selection criteria include reset threshold accuracy (±1.5% at +25°C), SRT pin ramp current (240nA), open-drain compatibility via external pullup, and SOT23-5 package suitability for space-constrained portable designs.

Technical Context

The MAX6424UK22 implements a precision voltage detector with laser-trimmed internal resistors to set its 2.188V reset threshold, validated across –40°C to +125°C with ±2.5% tolerance. Its reset assertion logic is triggered by VCC falling below VTH, with hysteresis of 4 × VTH (≈8.75mV) to prevent chatter.

Reset deassertion relies on an internal 240nA current source charging an external capacitor (CSRT) connected to the SRT pin; the voltage ramp must reach 0.65V to clear reset, yielding a timeout defined as tRP = 2.73×10⁶ × CSRT + 275µs. The push-pull output drives RESET low to 0.3V at 50µA sink current and high to 0.8×VCC at 200µA source current.

Key Specifications

Pinout & Package

MAX6424UK22 is housed in a 5-pin SOT23-5 package with exposed pad (not electrically connected), 1.27mm pitch, and RoHS-compliant lead-free finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP302LSN22T1G and MC33164D-2R2G, MAX6424UK22 provides uniquely adjustable reset timing in a compact SOT23-5 package with ultra-low 1.6µA quiescent current, making it optimal for modern battery-sensitive and space-constrained designs where timing precision matters.

Availability

MAX6424UK22 is available at Aetrix Electronics and suitable for portable medical sensors, battery-powered industrial controllers, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6424UK22 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 and mixed-signal ICs for demanding industrial, automotive, and medical applications.

The MAX6421–MAX6426 family delivers ultra-low-power, capacitor-programmable reset supervision for systems where supply stability, timing control, and extended temperature operation are critical.

FAQ

What is the exact reset threshold voltage of MAX6424UK22 and how is it trimmed?

The MAX6424UK22 has a nominal reset threshold of 2.188V, with ±1.5% accuracy at +25°C and ±2.5% over –40°C to +125°C. This value is achieved using factory laser-trimmed internal resistors, ensuring consistent performance without external calibration. The '22' suffix in MAX6424UK22 directly references the 2.188V threshold per Table 1 in the datasheet.

Can MAX6424UK22 operate reliably when VCC drops below 2.0V?

Yes, MAX6424UK22 guarantees valid reset assertion and deassertion down to VCC = 1.0V. Its internal circuitry remains functional and the push-pull RESET output maintains specified VOL (≤0.3V) and VOH (≥0.8×VCC) even at 1.0V supply, enabling robust brownout protection in deeply discharged battery scenarios.

How do I calculate the required SRT capacitor for a 3.5ms reset timeout with MAX6424UK22?

Use the formula CSRT = (tRP − 275µs) / 2.73×10⁶, where tRP = 3.5ms = 0.0035s. Substituting gives CSRT = (0.0035 − 0.000275) / 2.73×10⁶ ≈ 1182pF. A standard 1200pF ceramic capacitor meets this requirement and yields ~3.52ms timeout, well within datasheet tolerance.

Is MAX6424UK22 pin-compatible with other supervisors in the same family?

Yes, MAX6424UK22 shares identical 5-pin SOT23-5 pinout with MAX6340, MAX6425, and MAX6426. However, output type differs: MAX6424UK22 uses push-pull RESET, while MAX6425/MAX6426 use open-drain. Swapping requires verifying RESET load and logic compatibility - direct replacement is not assured without circuit review.

Does MAX6424UK22 require special PCB layout considerations for the SRT pin?

Yes - the SRT pin connects to a precision 240nA current source, so layout must minimize stray capacitance and leakage. Keep SRT traces short, avoid routing near high-speed signals or high-voltage nodes, and exclude test points or vias near the pin. Use clean prototype boards during evaluation to ensure accurate timeout period measurement.