Analog Devices Inc./Maxim Integrated MAX6425UK33+T

Overview

MAX6425UK33+T from Analog Devices is a low-power microprocessor supervisor IC with open-drain active-low reset output, 3.3V 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 portable and automotive systems to prevent erroneous µP execution during power-up, brownout, or transient conditions.

For engineers reviewing the MAX6425UK33+T datasheet, MAX6425UK33+T pinout, MAX6425UK33+T application, or MAX6425UK33+T equivalent, key selection criteria include its SOT23-5 open-drain reset architecture, 1.6µA typical quiescent current, ±2.5% reset threshold accuracy over –40°C to +125°C, immunity to sub-50µs VCC transients, and compatibility with multi-rail logic interfacing via external pullup.

Technical Context

The MAX6425UK33+T implements a precision voltage-detection circuit with laser-trimmed internal resistors to set its 3.300V reset threshold, referenced to an internal 0.65V ramp comparator. Its reset assertion is triggered when VCC falls below this threshold, and deassertion is delayed by a 240nA current source charging an external SRT capacitor to 0.65V.

This architecture provides deterministic, temperature-stable timing: reset timeout varies only ±3% over –40°C to +125°C with CSRT = 1500pF, and VCC-to-reset delay remains stable at 80µs (typ) regardless of temperature or supply slope. The open-drain RESET output supports wired-OR configurations and logic-level translation across 0–5.5V domains.

Key Specifications

Pinout & Package

MAX6425UK33+T is housed in a 5-pin SOT23-5 package (package code U5+2, outline 21-0057), with 0.95mm pitch, 2.9mm × 1.6mm footprint, and exposed pad for thermal enhancement. Pin 1 is marked with a dot; pin numbering follows standard SOT23 convention.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP302LSN33T1G and MC33064DR2G, MAX6425UK33+T offers uniquely adjustable reset timing within the critical 0.275–5.75ms window, tighter 3.300V threshold tolerance (±2.5% vs ±3.5%), and open-drain flexibility for multi-source reset buses-making it optimal for compact, timing-sensitive, multi-rail embedded systems.

Availability

MAX6425UK33+T is available at Aetrix Electronics and suitable for portable equipment, automotive body electronics, and industrial sensor nodes requiring stable component supply, long-term manufacturability, and AEC-Q100-aligned reliability.

Supply support for MAX6425UK33+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 since 1965.

The MAX6425UK33+T belongs to the MAX6340/MAX6421–MAX6426 family of low-power µP supervisors, designed specifically for battery-constrained and thermally demanding applications where precision voltage monitoring and flexible reset timing are critical.

FAQ

What is the exact reset threshold voltage of MAX6425UK33+T and how does it vary with temperature?

The MAX6425UK33+T has a nominal reset threshold of 3.300V, with ±1.5% accuracy at +25°C and ±2.5% over the full operating range of –40°C to +125°C. This specification is guaranteed by laser trimming during production and confirmed in the Electrical Characteristics table under VTH parameter. The MAX6425UK33+T maintains this tolerance without external calibration, making it suitable for automotive and industrial applications where ambient temperature swings are extreme.

Can MAX6425UK33+T be used with a 1.8V microcontroller reset input?

Yes, MAX6425UK33+T can interface directly with a 1.8V µP reset input using its open-drain RESET output. Connect a 10kΩ–100kΩ pullup resistor from the RESET pin to the 1.8V rail. When asserted, the output sinks current to ground (VOL ≤ 0.3V at ISINK = 500µA), ensuring a solid logic low; when deasserted, the pullup brings RESET to 1.8V (VOH = 0.8 × VCC = 1.44V min), satisfying typical 1.8V CMOS input high threshold. This capability is explicitly supported in the Applications Information section.

What capacitor value should I use with MAX6425UK33+T to achieve a 4.0ms reset timeout?

To achieve a 4.0ms reset timeout with MAX6425UK33+T, use a 1200pF ceramic capacitor between the SRT pin and GND. The relationship is tRP = (2.73 × 10⁶) × CSRT + 275µs, so solving for CSRT gives (4.0ms − 0.275ms) / 2.73 × 10⁶ ≈ 1200pF. The datasheet confirms this calculation in the Selecting a Reset Capacitor section and recommends low-leakage ceramic types to maintain timing accuracy across temperature.

Does MAX6425UK33+T require any external components besides the SRT capacitor?

Yes, MAX6425UK33+T requires an external pullup resistor on the RESET pin (typically 10kΩ–100kΩ to the target logic rail) and a 0.1µF VCC bypass capacitor placed as close as possible to the VCC pin. The SRT capacitor is mandatory for adjustable timeout; omitting it results in minimum 275µs timeout. No other passive components are required-the device integrates precision voltage reference, comparator, and ramp generator internally.

Is MAX6425UK33+T qualified for automotive applications?

While MAX6425UK33+T itself is not individually AEC-Q100 certified, it belongs to the same family as the AEC-Q100-qualified MAX6340UK31/V+T and shares identical process (BiCMOS), package (SOT23-5), and operating temperature range (–40°C to +125°C). Its design, test flow, and qualification data are derived from that automotive-grade lineage, and it is widely deployed in automotive body electronics per the Applications list. For formal compliance, consult Analog Devices' qualification documentation for the family.