Analog Devices Inc./Maxim Integrated MAX6423XS22

Overview

MAX6423XS22 from Maxim Integrated 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 base + 2.73s/F × CSRT), and guaranteed operation down to VCC = 1V. It monitors supply voltages from 1.6V to 5V in portable battery-powered controllers and automotive ECUs where precise brownout detection and flexible timeout are critical.

For engineers reviewing the MAX6423XS22 datasheet, MAX6423XS22 pinout, MAX6423XS22 application, or MAX6423XS22 equivalent, this page delivers verified technical context, exact SC70-4 pin mapping, real-world timing behavior under temperature variation, leakage-limited open-drain drive capability, and validated alternatives for voltage-monitoring reset circuits.

Technical Context

The MAX6423XS22 implements a precision bandgap-based voltage comparator with 2.5% threshold accuracy over –40°C to +125°C, coupled to a 240nA current source that charges an external capacitor on the SRT pin to generate the reset timeout delay. Its open-drain RESET output requires an external pullup and remains valid for VCC ≥ 1V, enabling compatibility with diverse logic supplies up to 5.5V.

Unlike push-pull variants, the MAX6423XS22 supports wired-OR reset configurations and multi-rail interfacing-its RESET line can be pulled up to any voltage ≤5.5V independent of VCC, making it suitable for systems with mixed-voltage µPs or auxiliary reset sources. Immunity to transients <50µs at 100mV overdrive is achieved via internal filtering of VCC glitches.

Key Specifications

Pinout & Package

MAX6423XS22 is housed in a 4-pin SC70-4 package (2.0mm × 2.1mm, 0.5mm pitch), optimized for space-constrained portable and automotive PCBs. The package supports reflow soldering and is available in lead-free (+T) variant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage-monitoring reset applications.

Compared with MAX6423XS22, the MAX6423US22-T offers identical functionality in a larger SOT143 package-suitable for manual assembly or thermal-heavy environments-while the NCP302LSN22T1G trades adjustability and open-drain versatility for lower quiescent current and simpler BOM, but cannot support wired-OR or multi-supply RESET routing.

Availability

MAX6423XS22 is available at Aetrix Electronics and suitable for battery-powered medical sensors, automotive body control modules, industrial handheld terminals, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6423XS22 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, emphasizing low power, high reliability, and small form factor.

The MAX6421–MAX6426 family targets ultra-low-power microprocessor supervision in space- and energy-constrained systems, delivering factory-trimmed voltage thresholds, capacitor-programmable timing, and robust transient immunity in sub-2mm packages.

FAQ

What is the exact reset threshold voltage of the MAX6423XS22 and how is it trimmed?

The MAX6423XS22 has a nominal reset threshold of 2.188V, with ±2.5% accuracy over –40°C to +125°C. This value is factory laser-trimmed using on-chip resistors, as confirmed in Table 1 of the datasheet (suffix "22" corresponds to 2.188V). No external calibration is required-the MAX6423XS22 delivers specified accuracy out-of-box across its full operating temperature range.

Can the MAX6423XS22 operate reliably when VCC drops below 1.6V?

Yes-the MAX6423XS22 guarantees functional reset assertion down to VCC = 1.0V, per Absolute Maximum Ratings and Electrical Characteristics tables. While its specified monitoring range starts at 1.6V, the device continues to assert RESET correctly as VCC falls to 1.0V, ensuring µP reset integrity during deep brownout conditions before complete power collapse.

How do I calculate the SRT capacitor value for a desired reset timeout period with the MAX6423XS22?

Use the formula CSRT = (tRP − 275µs) / 2.73×10⁶, where tRP is the desired timeout in seconds and CSRT is in farads. For example, a 100ms timeout requires CSRT = (0.1 − 0.000275) / 2.73×10⁶ ≈ 36.5nF. Ceramic capacitors with <10nA leakage are recommended, and layout best practices (short traces, no nearby digital signals) must be followed for accuracy.

Does the MAX6423XS22 support wired-OR reset configurations, and what pullup voltage can be used?

Yes-the MAX6423XS22 features an open-drain RESET output explicitly designed for wired-OR use. Its RESET pin can be pulled up to any voltage from 0V to 5.5V, independent of VCC. This allows direct interfacing with 1.8V, 3.3V, or 5V logic rails-even when VCC = 2.2V-without level shifters, as confirmed in Figure 1 and Applications Information sections.

What is the maximum allowable VCC transient duration that will not trigger a false reset on the MAX6423XS22?

Per the "Maximum Transient Duration vs. Reset Threshold Overdrive" graph (toc05), a VCC transient dipping 100mV below the 2.188V threshold (i.e., to 2.088V) will not cause a false reset if its duration is ≤50µs. Shorter overdrive magnitudes tolerate proportionally shorter pulses-for instance, a 50mV dip must be ≤15µs. This immunity is inherent to the internal ramp-comparator architecture and requires no external components.