Analog Devices Inc./Maxim Integrated MAX709LCUA+T

Overview

MAX709LCUA+T from Maxim Integrated is a precision power-supply monitor IC with active-low reset output, designed for +5V systems requiring 4.65V reset threshold, 140ms minimum power-on reset delay, and operation down to 1V VCC. It eliminates external components in microprocessor supervisory circuits for embedded controllers, industrial PLCs, and telecom line cards.

For engineers reviewing the MAX709LCUA+T datasheet, MAX709LCUA+T pinout, MAX709LCUA+T application, or MAX709LCUA+T equivalent, key selection criteria include reset threshold tolerance (±150mV), temperature-stable delay (140–560ms), low quiescent current (65µA typ), and µMAX-8 package compatibility with space-constrained PCB layouts.

Technical Context

The MAX709LCUA+T integrates a precision voltage comparator with hysteresis, internal timing capacitor, and open-drain RESET driver-no external RC network required. Its reset assertion is triggered when VCC drops below 4.50V (min) and held active for ≥140ms after VCC rises above 4.75V (max).

It operates across -40°C to +85°C (E-grade), supports VCC from 1.0V to 5.5V, and maintains valid RESET state down to 1V supply-enabling reliable brownout detection in battery-backed or low-voltage microcontroller systems without external pull-downs.

Key Specifications

Pinout & Package

MAX709LCUA+T uses an 8-pin µMAX package (3.0mm × 3.0mm, 0.5mm pitch), with pins 1, 4, 5, 6, and 8 unconnected internally (N.C.). Pin 2 supplies VCC, pin 3 is GND, and pin 7 delivers the active-low RESET signal.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power-supply monitor applications.

Compared with MAX709LCUA+T, MAX706PESA+ offers identical reset performance but lacks -40°C to +85°C qualification, while MAX792LESA+ adds watchdog and manual reset features unnecessary for simple power-fail detection-making MAX709LCUA+T the optimal choice for minimal-footprint, wide-temp supervisory applications.

Availability

MAX709LCUA+T is available at Aetrix Electronics and suitable for industrial PLC controllers, telecom line cards, and smart energy meters requiring stable component supply, long-term lifecycle support, and lead-free compliance.

Supply support for MAX709LCUA+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

Maxim Integrated (now part of Analog Devices) designs precision analog and mixed-signal ICs for industrial, medical, and communications applications, with expertise in power management and sensor signal conditioning.

The MAX709 family was engineered specifically for microprocessor supervisory functions in space- and cost-constrained systems-delivering accurate reset generation with zero external components across multiple supply voltages and temperature grades.

FAQ

What is the exact reset threshold voltage for MAX709LCUA+T?

The MAX709LCUA+T has a nominal reset threshold of 4.65V, with guaranteed limits of 4.50V (minimum) and 4.75V (maximum) over the full -40°C to +85°C operating temperature range. This threshold is factory-trimmed and does not require external adjustment-ensuring consistent power-fail detection in +5V systems without calibration.

Does MAX709LCUA+T require an external capacitor for reset timing?

No, the MAX709LCUA+T integrates a precision internal timing circuit that guarantees a minimum 140ms reset timeout after VCC rises above the threshold-no external capacitor is needed. This eliminates component count, reduces PCB area, and removes timing variation due to capacitor tolerance or aging, making MAX709LCUA+T ideal for high-reliability, low-BOM designs.

Can MAX709LCUA+T operate with VCC below 3.0V?

Yes, MAX709LCUA+T is fully specified down to VCC = 1.0V. Its RESET output remains valid and actively driven low until VCC falls below 1.0V, at which point it transitions to a high-impedance state. This behavior enables robust brownout detection in systems with decaying battery rails or unregulated input stages prior to LDO regulation.

What package type does MAX709LCUA+T use, and what are its dimensions?

MAX709LCUA+T uses the 8-pin µMAX package (also known as uSOP), measuring 3.0mm × 3.0mm with 0.5mm lead pitch. It is a surface-mount, lead-free package with exposed pad thermal enhancement, optimized for automated assembly and high-density routing in compact industrial and telecom modules.

How does MAX709LCUA+T handle short negative transients on the VCC line?

MAX709LCUA+T is immune to negative VCC transients ≤40µs in duration when the glitch magnitude is ≤100mV below the 4.65V threshold. This immunity prevents false resets caused by switching noise or ESD-induced supply dips-verified per Maxim's Figure 1 in the datasheet-and is enhanced by placing a 0.1µF ceramic capacitor directly at pin 2 (VCC).