Analog Devices Inc./Maxim Integrated MAX6426UK23

Overview

MAX6426UK23 from Maxim Integrated is a low-power microprocessor supervisor IC that monitors VCC supply voltage and asserts an active-low open-drain reset signal when voltage falls below 2.313V (typical threshold). It features capacitor-adjustable reset timeout (3.0–5.75ms with 1500pF), guaranteed operation down to VCC = 1V, and consumes only 1.6µA typical quiescent current. It is used in battery-powered controllers and automotive ECUs for reliable power-on reset and brownout protection.

For engineers reviewing the MAX6426UK23 datasheet, MAX6426UK23 pinout, MAX6426UK23 application, or MAX6426UK23 equivalent, key selection criteria include its 2.313V reset threshold accuracy (±2.5% over temperature), SOT23-5 open-drain output compatibility with mixed-voltage µP interfaces, capacitor-based timeout flexibility, and AEC-Q100 qualification relevance for automotive designs.

Technical Context

The MAX6426UK23 implements a precision voltage detector with laser-trimmed internal resistors to set its 2.313V nominal reset threshold, with ±2.5% tolerance across –40°C to +125°C. Its reset assertion logic is triggered by VCC falling below VTH, and deassertion is delayed by an internal 240nA current source charging an external capacitor (CSRT) to a 0.65V ramp threshold.

As an open-drain device, MAX6426UK23 requires an external pullup resistor (10kΩ–100kΩ) to any supply up to 5.5V, enabling wired-OR reset capability and logic-level translation across heterogeneous systems. It remains functional down to VCC = 1V, with RESET output leakage ≤1.0µA when not asserted.

Key Specifications

Pinout & Package

MAX6426UK23 is housed in a 5-pin SOT23-5 package with exposed pad (RoHS-compliant, lead-free). Pin 1 is VCC, Pin 2 is GND, Pin 3 is SRT (capacitor-connected timeout adjust), Pin 4 is N.C. (not internally connected), and Pin 5 is RESET (open-drain active-low output).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6426UK23, PST9223 offers identical pinout and threshold but sacrifices automotive qualification and ultra-low power, while NCP302LSN23T1G reduces current draw slightly but eliminates open-drain functionality essential for multi-device reset coordination.

Availability

MAX6426UK23 is available at Aetrix Electronics and suitable for automotive body control modules, battery-powered medical monitors, industrial PLC I/O modules, and set-top box power management requiring stable component supply across extended temperature and long-lifecycle programs.

Supply support for MAX6426UK23 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) designs precision analog, mixed-signal, and power management ICs for demanding industrial, automotive, and medical applications.

The MAX6421–MAX6426 family delivers ultra-low-power, capacitor-programmable reset supervisors optimized for battery-constrained and safety-critical systems where deterministic brownout response and wide temperature operation are mandatory.

FAQ

What is the exact reset threshold voltage of MAX6426UK23 and how does it vary with temperature?

The MAX6426UK23 has a nominal reset threshold of 2.313V, with ±1.5% accuracy at +25°C and ±2.5% over the full –40°C to +125°C operating range. This is confirmed by Table 1 in the datasheet, where suffix "23" corresponds to min/typ/max values of 2.255V/2.313V/2.371V. The normalized threshold vs. temperature curve (toc08) shows less than 0.5% drift across the range, ensuring consistent brownout detection in automotive under-hood environments.

How do I calculate the external capacitor value needed for a specific reset timeout with MAX6426UK23?

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 4.375ms timeout requires CSRT = (0.004375 – 0.000275) / 2,730,000 ≈ 1500pF. The datasheet specifies this relationship in the Pin Description section and validates it with electrical characteristics (tRP = 3.00–5.75ms at CSRT = 1500pF).

Can MAX6426UK23 drive a reset input directly on a 1.8V microcontroller?

Yes. The MAX6426UK23 open-drain RESET output can be pulled up to 1.8V using a 10kΩ–100kΩ resistor. Its VOL is guaranteed ≤0.3V at ISINK = 500µA and VCC ≥ 1.8V, ensuring solid logic-low assertion. This is explicitly supported in the Applications Information section under "Interfacing to Other Voltages for Logic Compatibility" and verified in the Electrical Characteristics table.

Is MAX6426UK23 qualified for automotive applications?

While MAX6426UK23 itself is not individually AEC-Q100 qualified, the MAX6426 family shares design and process with the AEC-Q100-qualified MAX6340UK31/V+T variant (stated in Benefits and Features). MAX6426UK23 is manufactured in the same BiCMOS process, operates across –40°C to +125°C, and meets all absolute maximum ratings and electrical specs required for automotive use - making it widely deployed in automotive modules where full qualification is not mandated.

What is the purpose of the N.C. pin (Pin 4) on MAX6426UK23, and how should it be handled on the PCB?

Pin 4 of MAX6426UK23 is Not Connected - no internal bond wire or circuitry. The datasheet Pin Description table explicitly states "Not Internally Connected." It may be left floating or tied to GND for mechanical stability; neither choice affects electrical performance. This is confirmed in the Pin Configurations diagram (page 7) and Selector Guide, which lists Pin 4 as N.C. for all SOT23 variants including MAX6426.