Analog Devices Inc./Maxim Integrated MAX6423XS25+T

Overview

MAX6423XS25+T from Analog Devices is a low-power microprocessor supervisor IC with open-drain active-low reset output, 2.5V nominal reset threshold (±2.5% over temperature), capacitor-adjustable reset timeout (3.0–5.75ms with 1500pF), and guaranteed operation down to VCC = 1V. It monitors supply voltage in portable and battery-powered systems to prevent erroneous µP execution during brownout.

For engineers reviewing the MAX6423XS25+T datasheet, MAX6423XS25+T pinout, MAX6423XS25+T application, or MAX6423XS25+T equivalent, key selection factors include its SC70-4 package, 1.6µA typical quiescent current, open-drain RESET compatibility with mixed-voltage µP interfaces, and factory-laser-trimmed 2.5V threshold with hysteresis.

Technical Context

The MAX6423XS25+T implements a precision voltage-detection circuit using laser-trimmed internal resistors to set a 2.5V reset threshold, with ±2.5% accuracy across –40°C to +125°C. Its SRT pin accepts an external capacitor to generate a programmable reset timeout via a 240nA ramp current charging to a 0.65V internal reference.

This device operates as a dedicated power-on reset supervisor: RESET asserts low when VCC falls below 2.5V and remains low for the timeout period after VCC rises above threshold. The open-drain output requires an external pullup and supports logic-level interfacing up to 5.5V, enabling use with diverse µP families.

Key Specifications

Pinout & Package

MAX6423XS25+T is housed in a 4-pin SC70-4 package (package code X4+1), measuring 1.25mm × 1.25mm × 0.9mm, suitable for space-constrained portable PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6423XS25+T, MAX6423US25+T offers identical supervision functionality in a larger, more thermally robust package, while NCP302LSN25T1G trades adjustable timing for lower quiescent current and push-pull simplicity - neither is pin-compatible, requiring layout or firmware adaptation.

Availability

MAX6423XS25+T is available at Aetrix Electronics and suitable for portable medical sensors, battery-powered industrial controllers, and automotive body control modules requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6423XS25+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 space- and energy-constrained embedded systems, emphasizing factory-trimmed accuracy and flexible reset timing.

FAQ

What is the exact reset threshold voltage of MAX6423XS25+T and how does it vary with temperature?

The MAX6423XS25+T has a nominal reset threshold of 2.500V, with ±1.5% accuracy at +25°C and ±2.5% over the full –40°C to +125°C operating range. This is achieved via laser-trimmed internal resistors, and the device includes 10mV hysteresis (4 × VTH) to prevent chatter near the threshold. The MAX6423XS25+T datasheet specifies VTH = 2.438V (min) to 2.563V (max) at +25°C, and the normalized curve shows <±0.5% drift across temperature.

How do I calculate the SRT capacitor value for a desired reset timeout period with MAX6423XS25+T?

Use the formula CSRT = (tRP – 275µs) / 2.735 × 10⁶, where tRP is the desired timeout in seconds and CSRT is in farads. For example, a 4.375ms timeout requires CSRT = (0.004375 – 0.000275) / 2.735e6 = 1500pF. The MAX6423XS25+T datasheet confirms this relationship applies across –40°C to +125°C, and recommends low-leakage ceramic capacitors.

Can MAX6423XS25+T drive a reset input directly, or does it require external components?

The MAX6423XS25+T features an open-drain RESET output and requires an external pullup resistor (typically 10kΩ–100kΩ) to a logic supply (0–5.5V). It cannot drive a reset input directly like a push-pull device. When asserted, RESET sinks up to 50µA at 0.3V (VCC ≥ 1.0V); when deasserted, the pullup defines the high level. This architecture enables level-shifting and wired-OR reset combining.

Is MAX6423XS25+T qualified for automotive applications?

The MAX6423XS25+T itself is not AEC-Q100 qualified; only the MAX6340UK31/V+T variant in the same family carries AEC-Q100 Grade 1 qualification. However, MAX6423XS25+T operates across –40°C to +125°C and meets automotive ambient temperature requirements. For production automotive ECUs, Analog Devices recommends the AEC-Q100-qualified MAX6340 variants instead of MAX6423XS25+T.

What is the minimum supply voltage at which MAX6423XS25+T guarantees valid RESET output?

The MAX6423XS25+T guarantees valid RESET output down to VCC = 1.0V, meaning it will correctly assert or deassert the open-drain signal even when the supply drops to 1V. Below 1V, RESET current-sinking capability declines sharply. This feature is explicitly specified in the Electrical Characteristics table and distinguishes MAX6423XS25+T from many competitors that require ≥1.5V for reset validity.