Analog Devices Inc./Maxim Integrated MAX709MCUA

Overview

MAX709MCUA from Maxim Integrated is a precision power-supply monitor IC with active-low reset output, designed for +3.3V systems. It asserts RESET when VCC falls below 4.40V (±150mV), holds reset for ≥140ms after VCC recovers, operates down to 1V supply, consumes only 65µA typical supply current, and is housed in an 8-pin µMAX package.

For engineers reviewing the MAX709MCUA datasheet, MAX709MCUA pinout, MAX709MCUA application, or MAX709MCUA equivalent, key selection criteria include reset threshold accuracy (4.40V nominal), guaranteed reset assertion at VCC ≥1V, immunity to short negative VCC transients (<40µs at 100mV overdrive), and compatibility with microprocessor reset inputs requiring open-drain or push-pull drive.

Technical Context

The MAX709MCUA integrates a precision voltage comparator with hysteresis, internal timing capacitor, and open-drain RESET driver. Its reset threshold is factory-trimmed to 4.40V and exhibits ±0.15% temperature drift over –40°C to +85°C. The device uses bandgap reference technology and requires no external components for basic operation.

It features a fixed 140ms minimum reset timeout after power-up, supports bidirectional µP reset pins via series resistor interface, and maintains valid RESET state during brownout conditions where VCC drops as low as 1.0V - ensuring deterministic system initialization without external supervision logic.

Key Specifications

Pinout & Package

MAX709MCUA is supplied in an 8-pin µMAX package (3mm × 3mm, 0.5mm pitch), thermally enhanced with exposed pad connected to GND. Pin 1 is top-left corner (marked dot), pin numbering follows standard counter-clockwise sequence.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX709MCUA, MAX706MCSA offers identical electrical behavior in a larger SO-8 package ideal for prototyping, while TPS3808G33DBVR trades fixed timing and N.C. pin flexibility for size reduction and configurability - making MAX709MCUA optimal for space-constrained industrial designs requiring guaranteed 140ms reset hold and proven glitch immunity.

Availability

MAX709MCUA is available at Aetrix Electronics and suitable for industrial PLC controllers, medical handheld diagnostics, and automotive infotainment head units requiring stable component supply, long-term lifecycle support, and guaranteed reset reliability under brownout conditions.

Supply support for MAX709MCUA 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) is a semiconductor company specializing in analog, mixed-signal, and power-management ICs for industrial, communications, and consumer applications.

The MAX709 family was engineered specifically for cost-sensitive, high-reliability microprocessor supervisory functions - delivering precise reset thresholds, minimal external component count, and robust transient immunity in compact packages.

FAQ

What is the exact reset threshold voltage for MAX709MCUA?

The MAX709MCUA has a factory-trimmed nominal reset threshold of 4.40V, with a guaranteed tolerance of ±150mV over the full operating temperature range (–40°C to +85°C). This value is specified in the Electrical Characteristics table of the official MAX709 datasheet and applies exclusively to the 'M' suffix variant. The MAX709MCUA will assert its active-low RESET output whenever VCC falls below this threshold and maintain it for at least 140ms after VCC rises above it.

Does MAX709MCUA require external components to function?

No, the MAX709MCUA operates autonomously without external resistors, capacitors, or trimming components. Its internal voltage reference, timing circuitry, and comparator are fully integrated. A 0.1µF ceramic bypass capacitor is recommended on the VCC pin (pin 2) for noise immunity, but this is a best-practice decoupling measure - not a functional requirement for basic reset generation. The MAX709MCUA delivers complete power-supply monitoring functionality in a single 8-pin µMAX package.

Can MAX709MCUA drive a microprocessor reset pin directly?

Yes, the MAX709MCUA's open-drain RESET output (pin 7) can directly interface with most µP reset inputs when used with an appropriate external pull-up resistor (typically 10kΩ to VCC). For µPs with bidirectional reset I/O (e.g., Motorola 68HC11), a 4.7kΩ series resistor between MAX709MCUA's RESET and the µP pin prevents contention. The MAX709MCUA guarantees valid output state down to VCC = 1.0V, ensuring deterministic reset behavior across the entire operational supply range.

What is the supply current consumption of MAX709MCUA?

The MAX709MCUA draws 65µA typical supply current at VCC = 5.5V, as specified in the Electrical Characteristics table. This value increases slightly with temperature but remains below 200µA across the full –40°C to +85°C range. The low quiescent current enables use in battery-backed systems and always-on monitoring applications without significant impact on standby power budget. Supply current is independent of RESET output state - it remains constant whether RESET is asserted or released.

Is MAX709MCUA compatible with 3.3V-only systems?

Yes, the MAX709MCUA is explicitly designed for +3.3V systems, with its 4.40V reset threshold positioned to trigger reliably before the 3.3V supply rail violates logic-level specifications. It operates correctly with VCC as low as 1.0V and up to 5.5V, allowing seamless integration into mixed-voltage boards where 3.3V logic coexists with 5V peripherals. Its guaranteed reset assertion at VCC ≥1V ensures fail-safe behavior even during severe brownout events affecting the 3.3V domain.