Analog Devices Inc./Maxim Integrated MAX6423US22

Overview

MAX6423US22 from Maxim Integrated is a low-power microprocessor reset supervisor IC with open-drain active-low RESET output, 2.188V ±2.5% factory-trimmed reset threshold, and capacitor-adjustable reset timeout (275µs base + 2.73s/F × CSRT). It operates from 1.0V to 5.5V supply, draws 1.6µA typical quiescent current, and guarantees valid reset assertion down to VCC = 1V - used in battery-powered controllers and medical instrumentation for reliable brownout detection.

For engineers reviewing the MAX6423US22 datasheet, MAX6423US22 pinout, MAX6423US22 application, or MAX6423US22 equivalent, key selection criteria include its SOT143-4 open-drain output topology, 2.188V reset threshold accuracy over –40°C to +125°C, capacitor-based timeout flexibility, guaranteed operation at VCC ≥ 1V, and immunity to sub-50µs VCC transients when overdriven by 100mV.

Technical Context

The MAX6423US22 implements a precision voltage monitor with laser-trimmed reference and hysteresis (4×VTH), coupled to a 240nA constant-current ramp generator charging an external capacitor on the SRT pin. Reset deassertion occurs when the SRT voltage reaches 0.65V ±33mV, enabling accurate timeout tuning independent of supply voltage.

Its open-drain RESET output supports wired-OR configurations and logic-level translation across 0–5.5V domains via external pullup. The device asserts reset on VCC falling below 2.188V and holds it for the full timeout period after VCC rises above threshold - ensuring µP initialization stability during power-up, brownout, and transient events.

Key Specifications

Pinout & Package

MAX6423US22 is housed in a 4-pin SOT143-4 package (outline 21-0052), surface-mount, RoHS-compliant, with 1.3mm × 1.3mm footprint and 0.95mm height.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6423US22, MAX6423XS22-T offers identical performance in a smaller package but requires different PCB layout and thermal validation, while NCP302LSN22T1G trades timeout adjustability and open-drain flexibility for lower cost and pin count - making it suitable only where those features are non-critical.

Availability

MAX6423US22 is available at Aetrix Electronics and suitable for battery-powered medical sensors, automotive body control modules, and portable industrial data loggers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6423US22 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) is a semiconductor company specializing in analog, mixed-signal, and power management ICs for industrial, automotive, and computing applications.

The MAX6421–MAX6426 family was designed specifically for ultra-low-power microprocessor supervision in space- and energy-constrained systems, emphasizing precision threshold accuracy, flexible timeout, and robust transient immunity.

FAQ

What is the exact reset threshold voltage of MAX6423US22 and how is it trimmed?

The MAX6423US22 has a factory-laser-trimmed reset threshold of 2.188V, with ±2.5% accuracy over –40°C to +125°C. This value is defined by the '22' suffix per Table 1 in the datasheet and is achieved using on-chip laser-trimmed resistors - eliminating external components and ensuring consistent performance across units without calibration.

Can MAX6423US22 operate reliably when VCC drops below 1.5V?

Yes - the MAX6423US22 guarantees valid reset assertion down to VCC = 1.0V, and its reset output remains functional through the entire 1.0V–5.5V supply range. At VCC < 1.0V, RESET behavior is not specified; however, for applications requiring validity down to 0V, a 100kΩ pulldown resistor on the open-drain RESET line is recommended to hold it low.

How do I calculate the external capacitor value for a 500ms reset timeout with MAX6423US22?

Use the formula CSRT = (tRP − 275µs) / 2.73×10⁶, where tRP = 0.5s. This gives CSRT ≈ 183nF. Select a low-leakage ceramic capacitor (X7R or C0G, <10nA leakage) and verify timing with actual board layout - stray capacitance on the SRT trace must be minimized per layout guidelines to avoid timeout error.

Is MAX6423US22 pin-compatible with any industry-standard alternatives?

No - MAX6423US22 is not pin-compatible with standard alternatives. Its 4-pin SOT143-4 pinout (VCC, GND, SRT, RESET) differs from 3-pin supervisors like NCP302 and 5-pin variants like MAX6425. While MAX6423XS22-T shares identical functionality in SC70-4, it uses a different pinout and footprint, requiring PCB redesign.

Does MAX6423US22 require external components to function as a basic reset supervisor?

Yes - MAX6423US22 requires two external components: a timing capacitor between SRT and GND to set the reset timeout period, and a pullup resistor on the open-drain RESET pin (typically 10kΩ–100kΩ) to define the high-state logic level. No external resistors are needed for threshold setting, as it is factory-trimmed.