Analog Devices Inc./Maxim Integrated MAX6426UK29+T

Overview

MAX6426UK29+T from Analog Devices is a low-power microprocessor supervisor IC that monitors 2.925V supply voltage and asserts an active-low open-drain RESET signal during brownout, power-up, or power-down events. It features capacitor-adjustable reset timeout (3.0–5.75ms with 1500pF), guaranteed operation down to VCC = 1V, and 1.6µA typical quiescent current. It is used in battery-powered embedded controllers requiring reliable, low-power reset supervision.

For engineers reviewing the MAX6426UK29+T datasheet, MAX6426UK29+T pinout, MAX6426UK29+T application, or MAX6426UK29+T equivalent, key selection criteria include its 2.925V reset threshold accuracy (±1.5% at +25°C), SOT23-5 open-drain output architecture, capacitor-programmable timeout, immunity to sub-50µs VCC transients, and AEC-Q100 qualification eligibility via family variants.

Technical Context

The MAX6426UK29+T implements a precision voltage-detection circuit with laser-trimmed internal resistors to set its 2.925V reset threshold. Its reset assertion logic is triggered when VCC falls below this threshold, and deassertion is delayed by an externally adjustable timeout determined by a ramp current (240nA) charging an SRT-to-ground capacitor.

As an open-drain supervisor, it requires an external pullup resistor (10kΩ–100kΩ) to a logic rail up to 5.5V, enabling flexible interfacing with µPs operating at different I/O voltages. It guarantees valid RESET output down to VCC = 1V but does not support valid logic at VCC = 0 without external biasing.

Key Specifications

Pinout & Package

MAX6426UK29+T is housed in a 5-pin SOT23-5 package (package code U5+2), with exposed pad optional per land pattern 90-0174. 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 NCP302HS29T1G and PST9229Q, MAX6426UK29+T offers field-tunable reset duration, lower power (1.6µA vs ≥3.5µA), and broader industrial temperature support, making it optimal for space-constrained, battery-critical, or automotive-adjacent applications requiring design flexibility.

Availability

MAX6426UK29+T is available at Aetrix Electronics and suitable for battery-powered medical sensors, automotive body control modules, and industrial PLC I/O subsystems requiring stable component supply, long-lifecycle assurance, and RoHS-compliant packaging.

Supply support for MAX6426UK29+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 MAX6421–MAX6426 product line delivers ultra-low-power, capacitor-programmable reset supervisors for space- and energy-constrained embedded systems where deterministic power-on reset timing and brownout resilience are critical.

FAQ

What is the exact reset threshold voltage of MAX6426UK29+T?

The MAX6426UK29+T has a nominal reset threshold of 2.925V, with ±1.5% accuracy at +25°C and ±2.5% over −40°C to +125°C. This value is laser-trimmed at wafer test and corresponds to the "29" suffix in the part number per Table 1 of the datasheet. The threshold is referenced to the VCC pin and remains stable across temperature and supply variations.

Can MAX6426UK29+T be used with a 1.8V microcontroller I/O rail?

Yes, MAX6426UK29+T can interface with a 1.8V µP I/O rail because its open-drain RESET output supports pullup to any voltage from 0V to 5.5V. When pulled up to 1.8V, the output high level is 1.8V (VOH = 0.8 × VCC_pullup), and VOL remains ≤0.3V at ISINK = 500µA. No level shifter is required, preserving signal integrity and board area.

How do I calculate the capacitor value for a 4.0ms reset timeout with MAX6426UK29+T?

To achieve a 4.0ms reset timeout with MAX6426UK29+T, use the formula CSRT = (tRP − 275µs) / 2.735 × 10⁶, where tRP = 0.004s. This yields CSRT ≈ 1360pF. A standard 1500pF X7R ceramic capacitor is recommended, delivering ~4.375ms typical timeout per datasheet specifications and providing margin against tolerance and temperature drift.

Is MAX6426UK29+T qualified for automotive applications?

MAX6426UK29+T itself is not individually AEC-Q100 qualified, but the MAX6340UK31/V+T variant in the same family is explicitly AEC-Q100 qualified. The MAX6426UK29+T shares identical process (BiCMOS), package (SOT23-5), and operating temperature range (−40°C to +125°C), and is widely deployed in automotive-adjacent applications such as body electronics and infotainment power management where qualification is customer-validated.

What is the purpose of the NC pin (Pin 3) on MAX6426UK29+T?

Pin 3 of MAX6426UK29+T is Not Connected (N.C.) - it has no internal bond wire or circuit connection. Per Analog Devices' pin description, it may be left floating or tied to GND for mechanical reinforcement of the SOT23-5 package on the PCB. It must never be connected to VCC, SRT, or any active signal, as it serves no electrical function and could risk contamination or shorts if misused.