Analog Devices Inc./Maxim Integrated MAX6423US16+T

Overview

MAX6423US16+T from Analog Devices is a low-power microprocessor supervisor IC with open-drain active-low reset output, 1.575V nominal reset threshold (±2.5% over temperature), 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 portable equipment to prevent erroneous code execution during brownout.

For engineers reviewing the MAX6423US16+T datasheet, MAX6423US16+T pinout, MAX6423US16+T application, or MAX6423US16+T equivalent, key selection criteria include its 4-pin SOT143 package, 1.6µA typical quiescent current, open-drain RESET compatibility with multiple logic supplies, immunity to short VCC transients, and factory-laser-trimmed reset threshold accuracy.

Technical Context

The MAX6423US16+T implements a precision voltage-detection circuit using laser-trimmed resistors to set a fixed 1.575V reset threshold, with hysteresis of 4×VTH (≈6.3mV). Its internal 240nA ramp current source charges an external capacitor on the SRT pin to generate a programmable reset timeout period.

Reset assertion occurs when VCC falls below the threshold; deassertion requires both VCC rise above threshold and full capacitor ramp to 0.65V. The open-drain RESET output supports wired-OR configurations and logic-level translation via external pullup, enabling interface with µPs operating at voltages from 0V to 5.5V.

Key Specifications

Pinout & Package

MAX6423US16+T is housed in a 4-pin SOT143 package (package code U4+1), with 1.3mm × 1.3mm footprint and 0.95mm height. Pin 1 is VCC, Pin 2 is GND, Pin 3 is RESET (open-drain), and Pin 4 is SRT (capacitor-adjustable timeout input).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6423US16+T, MAX6423XS16+T offers identical functionality in a smaller package but reduced mechanical robustness, while NCP302LSN16T1G trades timeout flexibility and open-drain versatility for lower component count and simpler BOM - neither is pin-compatible, requiring layout revision.

Availability

MAX6423US16+T is available at Aetrix Electronics and suitable for battery-powered portable instruments, automotive body control modules, and medical wearable sensors requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6423US16+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 since 1965.

The MAX6421–MAX6426 family delivers ultra-low-power, precision voltage supervision for resource-constrained embedded systems where supply integrity directly impacts functional safety and data reliability.

FAQ

What is the exact reset threshold voltage of MAX6423US16+T and how does it vary with temperature?

The MAX6423US16+T has a nominal reset threshold of 1.575V, with tolerance of ±1.5% at +25°C and ±2.5% over the full –40°C to +125°C operating range. This corresponds to a minimum of 1.536V and maximum of 1.614V at room temperature, and 1.536V to 1.614V across temperature per the datasheet's normalized curve - ensuring consistent brownout detection without software compensation. The MAX6423US16+T uses laser-trimmed resistors to achieve this stability.

Can MAX6423US16+T be used with a 3.3V microcontroller that requires an active-high reset signal?

Yes, but requires external inversion: the MAX6423US16+T provides active-low open-drain RESET, so a pullup resistor to 3.3V establishes logic-high idle state, and RESET pulls low during fault. To generate active-high, add a single N-channel MOSFET or inverter buffer - however, note that the MAX6422US16+T variant offers native active-high push-pull output. The MAX6423US16+T itself cannot directly assert active-high without external components.

What capacitor value is needed to achieve a 4.0ms reset timeout with MAX6423US16+T?

Using the formula tRP = 2.73 × 10⁶ × CSRT + 275µs, solving for CSRT gives CSRT = (4.0ms − 0.275ms) / 2.73 × 10⁶ ≈ 1366pF. A standard 1500pF ceramic capacitor yields 4.375ms (within datasheet spec), while 1200pF yields ~3.55ms. Use low-leakage (<10nA) X7R or C0G dielectric; avoid electrolytics. The MAX6423US16+T's SRT pin is sensitive to board leakage, so keep traces short and clean.

Is MAX6423US16+T qualified for automotive applications?

The MAX6423US16+T is specified for –40°C to +125°C operation and built on Analog Devices' BiCMOS process, but it is not explicitly AEC-Q100 qualified. Only the MAX6340UK31/V+T variant in the same family carries AEC-Q100 Grade 2 certification. For automotive use, MAX6423US16+T may be deployed in non-safety-critical infotainment or comfort modules, but design validation per ISO 16750 and customer-specific qualification remains the responsibility of the end user. The MAX6423US16+T datasheet does not list AEC-Q100 test reports.

How does the open-drain RESET output of MAX6423US16+T interface with multiple voltage domains?

The open-drain RESET output of MAX6423US16+T can be pulled up to any voltage from 0V to 5.5V, enabling direct interface with 1.8V, 2.5V, 3.3V, or 5V microcontrollers without level shifters. A 10kΩ–100kΩ pullup resistor ensures logic-high recognition while limiting sink current to <500µA during assertion. This architecture supports wired-OR reset buses where multiple supervisors or safety circuits share one RESET line - a capability the MAX6423US16+T leverages in industrial control designs.