Analog Devices Inc./Maxim Integrated MAX6423US31+T

Overview

MAX6423US31+T from Analog Devices is a low-power microprocessor supervisor IC with open-drain active-low reset output, 3.075V nominal reset threshold (±2.5% over temperature), capacitor-adjustable reset timeout (3.0–5.75ms at CSRT = 1500pF), and guaranteed operation down to VCC = 1V. It monitors supply voltage in portable and battery-powered systems to prevent erroneous µP startup during brownout.

For engineers reviewing the MAX6423US31+T datasheet, MAX6423US31+T pinout, MAX6423US31+T application, or MAX6423US31+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 MAX6423US31+T implements a precision voltage-detection circuit using laser-trimmed resistors to set its 3.075V reset threshold, with ±2.5% tolerance across –40°C to +125°C. Its reset assertion is triggered by VCC falling below this threshold, and deassertion is delayed by an internal 240nA current source charging an external capacitor (CSRT) to a 0.65V ramp threshold.

This architecture ensures robust immunity to sub-50µs negative-going VCC transients when overdrive is ≤100mV, while guaranteeing valid RESET output down to VCC = 1V. The open-drain output requires an external pullup resistor (10kΩ–100kΩ) and supports wired-OR reset configurations with auxiliary circuitry.

Key Specifications

Pinout & Package

MAX6423US31+T is housed in a 4-pin SOT143 package (package code U4+1), measuring 2.1mm × 2.3mm × 1.1mm, RoHS-compliant and tape-and-reel packaged.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6423US31+T, NCP302LSN30T1G offers lower quiescent current but forfeits timeout configurability, while TLV803EB30DBZR provides superior threshold accuracy at the cost of inflexible, long reset duration - making MAX6423US31+T optimal for designs requiring both precision and timing adaptability.

Availability

MAX6423US31+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 MAX6423US31+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 semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.

The MAX6423US31+T belongs to the MAX6340/MAX6421–MAX6426 family of low-power µP supervisors, designed specifically for reliable power-monitoring in space-constrained, battery-sensitive, and thermally demanding applications.

FAQ

What is the exact reset threshold voltage of MAX6423US31+T and how does it vary with temperature?

The MAX6423US31+T has a nominal reset threshold of 3.075V, with ±1.5% accuracy at +25°C and ±2.5% over the full –40°C to +125°C operating range. This specification is laser-trimmed at wafer test and confirmed in the Electrical Characteristics table under VTH parameter conditions. The device maintains this tolerance without external calibration.

Can MAX6423US31+T operate reliably when VCC drops below 1.6V?

Yes - the MAX6423US31+T guarantees valid RESET output down to VCC = 1.0V, as stated in the "Guaranteed Reset Valid to VCC = 1V" feature and confirmed in Absolute Maximum Ratings. At VCC = 1.0V, RESET remains functional with VOL ≤ 0.3V at ISINK = 50µA, enabling robust brownout handling in ultra-low-voltage scenarios.

How do I calculate the external capacitor value for a specific reset timeout period with MAX6423US31+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 4.0ms timeout requires CSRT ≈ 1460pF. The datasheet specifies ceramic capacitors (<10nA leakage) for accuracy, and Figure 1 in the Typical Operating Circuit section validates this relationship.

Is MAX6423US31+T pin-compatible with any other supervisor ICs?

No - MAX6423US31+T uses a 4-pin SOT143 package with VCC, GND, RESET, and SRT pins. While MAX6424/MAX6425/MAX6426 variants are pin-compatible with NCP300–NCP303 or S807/S808/S809 families, those are 5-pin SOT23 devices. MAX6423US31+T has no documented pin-compatible alternatives in its 4-pin SOT143 footprint.

Does MAX6423US31+T require an external pullup resistor on the RESET pin, and what value is recommended?

Yes - because MAX6423US31+T features an open-drain RESET output, an external pullup resistor is mandatory. The datasheet recommends 10kΩ to 100kΩ, selected to ensure logic-high recognition while sinking required current (e.g., 500µA) during assertion. A 47kΩ resistor is commonly used for optimal noise immunity and power tradeoff.