Analog Devices Inc./Maxim Integrated MAX6423US23

Overview

MAX6423US23 from Maxim Integrated is a low-power microprocessor supervisor IC with open-drain active-low reset output, 2.313V factory-trimmed reset threshold, capacitor-adjustable reset timeout (275µs minimum), and guaranteed operation down to VCC = 1V. It monitors supply voltage in portable and battery-powered systems to prevent code-execution errors during power-up, brownout, or power-down events.

For engineers reviewing the MAX6423US23 datasheet, MAX6423US23 pinout, MAX6423US23 application, or MAX6423US23 equivalent, key selection criteria include its SOT143-4 package, 1.6µA quiescent current, open-drain RESET compatibility with multiple logic supplies, immunity to short VCC transients, and precise reset threshold accuracy over -40°C to +125°C.

Technical Context

The MAX6423US23 implements a precision voltage-monitoring circuit with laser-trimmed resistors to set its 2.313V reset threshold, ±1.5% at +25°C and ±2.5% over full temperature range. Its reset assertion is triggered by VCC falling below this threshold, and deassertion is delayed by an externally adjustable timeout determined by a ramp current (240nA) charging CSRT to a 0.65V internal reference.

As an open-drain device, MAX6423US23 requires an external pullup resistor (10kΩ–100kΩ) to a logic supply up to 5.5V, enabling wired-OR reset configurations and interfacing with µPs operating at different voltage domains. It guarantees valid RESET output down to VCC = 1V but is not specified for operation below that level.

Key Specifications

Pinout & Package

MAX6423US23 is housed in a 4-pin SOT143-4 surface-mount package (2.1mm × 2.3mm × 0.95mm), optimized for space-constrained portable and medical devices.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6423US23, MAX6423XS23-T offers identical supervision functionality in a smaller SC70 package but requires tighter assembly control, while NCP302LSN23T1G trades timeout adjustability and open-drain flexibility for lower unit cost and simpler BOM.

Availability

MAX6423US23 is available at Aetrix Electronics and suitable for battery-powered medical sensors, automotive body control modules, portable industrial handhelds, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6423US23 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 solutions for industrial, automotive, communications, and computing markets.

The MAX6421–MAX6426 family was designed specifically for low-power, precision voltage supervision in space- and energy-constrained embedded systems, emphasizing factory-trimmed thresholds, ultra-low IQ, and flexible reset timing.

FAQ

What is the exact reset threshold voltage of MAX6423US23, and how accurate is it over temperature?

The MAX6423US23 has a nominal reset threshold of 2.313V, factory-trimmed with ±1.5% accuracy at +25°C and ±2.5% accuracy over the full -40°C to +125°C operating range. This specification is guaranteed by design and verified in production testing, ensuring consistent brownout detection across automotive and industrial environments where supply rails may drift with temperature.

Can MAX6423US23 drive a reset input that operates at a different voltage than VCC?

Yes - MAX6423US23 features an open-drain RESET output, allowing it to interface with µP reset inputs operating at voltages from 0V to 5.5V. An external pullup resistor (typically 10kΩ–100kΩ) connects RESET to the target logic supply. This enables direct compatibility with 1.8V, 2.5V, 3.3V, or 5V reset domains without level-shifting circuitry, a key advantage over push-pull supervisors like MAX6421US23.

How do I calculate the external capacitor value needed for a specific reset timeout with MAX6423US23?

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 10ms timeout requires CSRT = (0.01 − 0.000275) / 2.73×10⁶ ≈ 3.56nF. A standard 3.3nF or 3.9nF X7R ceramic capacitor is recommended - low leakage (<10nA) is essential to maintain timing accuracy.

Is MAX6423US23 suitable for applications requiring reset assertion down to 0V VCC?

No - MAX6423US23 guarantees valid RESET output only down to VCC = 1.0V. Below that, sink current capability declines sharply, and the output may float. For true zero-VCC reset validity, a pulldown resistor (e.g., 100kΩ from RESET to GND) can hold the line low, but this adds static current and is not recommended for ultra-low-power designs. The datasheet explicitly states open-drain versions like MAX6423US23 are not intended for VCC = 0 operation.

What package type and dimensions does MAX6423US23 use, and how does it compare to similar parts?

MAX6423US23 uses the 4-pin SOT143-4 package (2.1mm × 2.3mm × 0.95mm body size). This differs from the SC70-4 variant (MAX6423XS23-T, 1.25mm × 1.65mm) and the 5-pin SOT23-5 used by MAX6425UK23-T. The SOT143 offers better thermal performance than SC70 and simpler routing than SOT23-5, making it ideal for compact yet thermally demanding applications like handheld instruments and automotive ECUs.