Analog Devices Inc./Maxim Integrated MAX6426UK26+

Overview

MAX6426UK26+ 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 2.625V (typical), with capacitor-adjustable reset timeout (275µs to >5ms), guaranteed operation down to VCC = 1V, and 1.6µA typical quiescent current - used in battery-powered controllers and automotive ECUs for reliable power-up/brownout reset control.

For engineers reviewing the MAX6426UK26+ datasheet, MAX6426UK26+ pinout, MAX6426UK26+ application, or MAX6426UK26+ equivalent, key selection considerations include its 2.625V reset threshold accuracy (±2.5% over -40°C to +125°C), SOT23-5 open-drain output requiring external pullup, capacitor-set timeout timing, immunity to sub-50µs VCC transients, and compatibility with logic supplies up to 5.5V.

Technical Context

The MAX6426UK26+ implements a precision voltage detector with laser-trimmed internal reference and 240nA SRT ramp current source, comparing VCC against a factory-set 2.625V threshold (suffix "26") with 4mV hysteresis. Its open-drain RESET output remains asserted until the external SRT capacitor charges to 0.65V after VCC recovers.

It operates across -40°C to +125°C, supports VCC from 1.0V to 5.5V, and guarantees valid RESET assertion down to VCC = 1V. Immunity to short VCC transients is achieved via internal filtering - a 100mV-overdrive negative transient lasting ≤50µs typically avoids false reset assertion.

Key Specifications

Pinout & Package

MAX6426UK26+ is housed in a 5-pin SOT23-5 package (JEDEC MO-178AA, land pattern 90-0174), with exposed pad not electrically connected. Pin 3 is NC (not internally connected) and may be tied to GND for mechanical stability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PST9226 and NCP302HS26T1G, MAX6426UK26+ uniquely delivers capacitor-programmable reset timing, lower quiescent current (1.6µA), and documented immunity to 50µs VCC transients - making it optimal for battery-constrained and automotive-grade systems demanding precise, adaptive reset control.

Availability

MAX6426UK26+ is available at Aetrix Electronics and suitable for battery-powered medical sensors, automotive engine control units, and industrial programmable logic controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6426UK26+ 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 and mixed-signal ICs for industrial, automotive, and computing applications, emphasizing high reliability and low power.

The MAX6421–MAX6426 family delivers ultra-low-power, capacitor-adjustable reset supervision for space-constrained and energy-sensitive systems - targeting portable, automotive, and medical equipment where deterministic power-on reset is critical.

FAQ

What is the exact reset threshold voltage of MAX6426UK26+ and how tightly is it specified?

The MAX6426UK26+ has a nominal reset threshold of 2.625V, with ±1.5% accuracy at +25°C and ±2.5% over the full -40°C to +125°C operating range. This tolerance is guaranteed by laser trimming during manufacturing and confirmed in the Electrical Characteristics table of the official datasheet. The "26" suffix explicitly denotes this 2.625V threshold variant.

Does MAX6426UK26+ support operation down to 1.0V VCC, and what happens to RESET functionality at that level?

Yes, MAX6426UK26+ guarantees valid RESET assertion down to VCC = 1.0V. At this voltage, the open-drain output maintains sink capability (VOL ≤ 0.3V at 500µA), ensuring reliable logic-low signaling. Below 1.0V, sink current declines significantly - so for applications requiring reset validity down to 0V, an external pulldown resistor is recommended per Figure 3 in the datasheet.

How is the reset timeout period set on MAX6426UK26+, and what capacitor value yields a 4ms timeout?

The reset timeout on MAX6426UK26+ is set by connecting a capacitor (CSRT) between pin 4 (SRT) and GND. Using the formula tRP = (2.73 × 10⁶) × CSRT + 275µs, a 4ms timeout requires CSRT ≈ 1370pF. A standard 1500pF ceramic capacitor yields 4.375ms (typ), matching the datasheet's tRP specification at that value.

Can MAX6426UK26+ be used in a wired-OR reset configuration, and what design precautions apply?

Yes, MAX6426UK26+'s open-drain RESET output is expressly designed for wired-OR configurations. Connect its RESET pin directly to other open-drain reset sources (e.g., watchdog ICs) and a shared pullup. Ensure total leakage into the node stays below 1µA and pullup value is 10kΩ–100kΩ - as specified in the Applications Information section - to guarantee clean logic transitions.

Is MAX6426UK26+ qualified for automotive applications, and what evidence supports this?

While MAX6426UK26+ itself is not individually AEC-Q100 certified, the MAX6340 variant (same family, same SOT23-5 package and open-drain architecture) is explicitly AEC-Q100 qualified (MAX6340UK31/V+T). The MAX6426UK26+ shares identical process (BiCMOS), package, absolute maximum ratings, and operating temperature range (-40°C to +125°C), and is widely deployed in automotive subsystems per distributor application notes and design-in history.