Analog Devices Inc./Maxim Integrated MAX6425UK34+T

Overview

MAX6425UK34+T from Analog Devices is a low-power microprocessor supervisor IC with open-drain active-low reset output, 3.4V nominal reset threshold (±2.5% over temperature), capacitor-adjustable reset timeout (3.0–5.75ms with 1500pF), and guaranteed operation down to VCC = 1V. It monitors supply voltage in battery-powered embedded controllers and portable equipment to prevent code execution errors during brownout.

For engineers reviewing the MAX6425UK34+T datasheet, MAX6425UK34+T pinout, MAX6425UK34+T application, or MAX6425UK34+T equivalent, key selection criteria include reset threshold accuracy, open-drain logic compatibility with mixed-voltage µP interfaces, capacitor-set timeout flexibility, and guaranteed reset validity at VCC ≥ 1V for robust power sequencing.

Technical Context

The MAX6425UK34+T implements a precision voltage-detection architecture using laser-trimmed resistors to set its 3.4V reset threshold, with ±2.5% tolerance across –40°C to +125°C. Its internal 240nA SRT ramp current charges an external capacitor to generate the reset timeout delay.

Reset assertion occurs when VCC falls below the threshold; deassertion requires both VCC rise above threshold and full capacitor ramp to 0.65V. The open-drain RESET output supports wired-OR configuration and logic-level translation via external pullup to any supply ≤5.5V.

Key Specifications

Pinout & Package

MAX6425UK34+T is housed in a 5-pin SOT23-5 package (package code U5+2), RoHS-compliant, tape-and-reel format. Pin 1 is VCC, Pin 2 is GND, Pin 3 is SRT (capacitor-adjustable timeout input), Pin 4 is RESET (open-drain active-low output), and Pin 5 is NC (not internally connected).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6425UK34+T, NCP302LSN34T1G offers simpler implementation but sacrifices timing flexibility and logic-level adaptability, while TLV809EC29DBVR trades threshold precision and configurable delay for lower quiescent current - making MAX6425UK34+T optimal for designs requiring accurate 3.4V detection with field-tunable reset hold time.

Availability

MAX6425UK34+T is available at Aetrix Electronics and suitable for battery-powered portable equipment, automotive body control modules, and industrial embedded controllers requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6425UK34+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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The MAX6421–MAX6426 family was designed specifically for low-power microprocessor supervision in space-constrained, battery-sensitive applications demanding precision voltage monitoring and flexible reset timing.

FAQ

What is the exact reset threshold voltage of MAX6425UK34+T?

The MAX6425UK34+T has a nominal reset threshold of 3.400V, with ±2.5% accuracy over the full operating temperature range of –40°C to +125°C. This value is laser-trimmed at the factory and specified in Table 1 of the datasheet under suffix "34". The actual threshold remains stable across voltage and temperature variations, ensuring consistent brownout detection behavior in critical applications.

How do I calculate the SRT capacitor value for a 4.5ms reset timeout with MAX6425UK34+T?

For a 4.5ms reset timeout, use the formula CSRT = (tRP – 275µs) / 2.735 × 10⁶, where tRP = 0.0045s. This yields CSRT ≈ 1550pF. A standard 1500pF ceramic capacitor (X7R, low-leakage <10nA) is recommended and will produce a timeout within the specified 3.00–5.75ms range at 25°C. The MAX6425UK34+T's SRT pin must be routed with minimal trace length and isolation from noisy signals to preserve timing accuracy.

Can MAX6425UK34+T drive a 3.3V microcontroller reset input directly?

Yes, MAX6425UK34+T can drive a 3.3V µP reset input directly using an external 10kΩ–100kΩ pullup resistor to 3.3V. Its open-drain RESET output sinks ≥500µA at VOL ≤ 0.3V (VCC ≥ 1.8V), ensuring solid logic-low assertion, and presents high impedance when deasserted - allowing the pullup to define the logic-high level. No level-shifter is required, simplifying interface design.

Is MAX6425UK34+T qualified for automotive applications?

While MAX6425UK34+T shares the same die and SOT23-5 package as AEC-Q100-qualified variants like MAX6340UK31/V+T, the MAX6425UK34+T itself is not explicitly AEC-Q100 certified per the datasheet. It operates across –40°C to +125°C and meets automotive-grade reliability screening, but formal qualification applies only to designated part numbers. For safety-critical automotive use, consult Analog Devices' official qualification documentation before deployment.

Does MAX6425UK34+T require decoupling capacitors on VCC?

Yes, a 0.1µF ceramic decoupling capacitor placed as close as possible to the MAX6425UK34+T VCC and GND pins is strongly recommended. This suppresses high-frequency noise that could affect threshold detection accuracy or induce false resets. The device's internal comparator and ramp circuitry are sensitive to supply transients; proper local decoupling ensures stable operation, especially in noisy environments such as motor drives or switching power supplies.