Analog Devices Inc./Maxim Integrated MAX709RCUA

Overview

MAX709RCUA from Maxim Integrated is a precision power-supply monitor IC with active-low reset output, designed for +5V/+3.3V/+3V systems. It asserts RESET when VCC falls below 2.63V (±2%), holds reset for ≥140ms after VCC recovers, and guarantees valid output down to VCC = 1V. Used in microprocessor-based embedded controllers to prevent erratic startup or brownout operation.

For engineers reviewing the MAX709RCUA datasheet, MAX709RCUA pinout, MAX709RCUA application, or MAX709RCUA equivalent, key selection criteria include reset threshold accuracy (±2% at 2.63V), guaranteed 140ms minimum reset timeout, immunity to short VCC transients (<40µs at 100mV overdrive), low quiescent current (35µA typ), and µMAX-8 package compatibility with space-constrained PCB layouts.

Technical Context

The MAX709RCUA integrates a precision voltage comparator, internal timing capacitor, and open-drain RESET driver. Its reset threshold is factory-trimmed to 2.63V with ±2% tolerance over −40°C to +85°C, and its power-on reset delay is fixed at ≥140ms (typ 280ms) without external components.

It operates across VCC = 1.0V to 5.5V, sinks up to 1.2mA at VCC = reset threshold min, and remains functional during fast VCC transients (rate-of-rise up to 100V/µs). The device features no external adjustments and requires only a 0.1µF bypass capacitor on VCC for robust noise immunity.

Key Specifications

Pinout & Package

MAX709RCUA is housed in an 8-pin µMAX package (3mm × 3mm, 0.5mm pitch), with exposed pad for thermal enhancement. Pin 1 is top-left corner (notch-marked), and pins 1–4 run counterclockwise along top edge; pins 5–8 run clockwise along bottom edge.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX709RCUA, MAX706R offers identical electrical behavior in a legacy SO-8 package with higher IQ, while TPS3808G12DBVR trades pin count and simplicity for tighter threshold tolerance and orders-of-magnitude lower supply current - but requires external components and sacrifices the µMAX's compact 3×3mm footprint.

Availability

MAX709RCUA is available at Aetrix Electronics and suitable for industrial PLC I/O modules, medical sensor nodes, and smart energy meters requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature.

Supply support for MAX709RCUA 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 communications applications, with emphasis on reliability, integration, and low-power operation.

The MAX709RCUA belongs to Maxim's µP supervisory circuit family, engineered specifically for deterministic power-on/brownout reset generation in resource-constrained embedded systems without external timing or trimming components.

FAQ

What is the exact reset threshold voltage of the MAX709RCUA?

The MAX709RCUA has a factory-trimmed nominal reset threshold of 2.63V with ±2% tolerance over the full operating temperature range (−40°C to +85°C). This value is specified in the Electrical Characteristics table under "RESET Threshold, VTH" for suffix R, and confirmed by the Ordering Information section listing R = 2.63V. The MAX709RCUA maintains this threshold stability without external calibration.

Does the MAX709RCUA require external components to function?

No, the MAX709RCUA operates autonomously with no external resistors, capacitors, or trim pots required. Its 140ms reset timeout is generated internally, and the 2.63V threshold is laser-trimmed at wafer test. Only a 0.1µF ceramic bypass capacitor on VCC (pin 2) is recommended for transient immunity - not strictly required for basic functionality but essential for robust field operation.

Can the MAX709RCUA drive a microprocessor reset pin directly?

Yes, the MAX709RCUA RESET output (pin 7) is an open-drain driver capable of sinking ≥1.2mA at VCC = reset threshold minimum, which meets or exceeds the reset pin sink requirements of most 8-/16-bit microcontrollers. An external pull-up resistor (typically 10kΩ to host VCC) is required to establish the high state; no level-shifter is needed for 3.3V or 5V µPs.

What is the minimum VCC voltage at which the MAX709RCUA guarantees correct RESET output state?

The MAX709RCUA guarantees correct RESET output state down to VCC = 1.0V. Below 1.0V, the RESET output becomes high-impedance (open-circuit) and no longer actively sinks current. This behavior is explicitly stated in the General Description and Electrical Characteristics sections, ensuring predictable reset assertion through the critical low-voltage region where µP logic becomes unreliable.

Is the MAX709RCUA pin-compatible with other MAX709 variants like MAX709SCUA or MAX709TCUA?

Yes, all MAX709 variants including MAX709RCUA, MAX709SCUA, and MAX709TCUA share identical pinout, package (µMAX-8), and terminal functions. The only difference is the factory-set reset threshold voltage (2.63V for R, 2.93V for S, 3.08V for T). No PCB layout change is required when substituting between these suffixes - only the functional reset point changes.