Analog Devices Inc./Maxim Integrated MAX6709LUB+

Overview

The MAX6709LUB+ from Maxim Integrated is a low-power, quad voltage monitor IC designed for multivoltage system supervision. It provides four independent active-low open-drain power-good outputs (PWRGD1–PWRGD4), monitors adjustable/programmable thresholds at IN1 and IN4 (down to 0.62V), fixed 3.3V and 1.8V supplies with ±5% tolerance, and consumes only 35µA typical supply current across 2.0V–5.5V VCC. It is used in desktop/notebook computers and networking equipment for reliable power sequencing and fault detection.

For engineers reviewing the MAX6709LUB+ datasheet, MAX6709LUB+ pinout, MAX6709LUB+ application, or MAX6709LUB+ equivalent, key selection considerations include its factory-configured 3.3V/1.8V monitoring pair with 5% tolerance, dual adjustable inputs (IN1/IN4), 10-pin µMAX package, -40°C to +85°C operation, and compatibility with wire-ORed power-good signaling in multirail systems.

Technical Context

The MAX6709LUB+ implements four precision comparators with an internal 0.62V bandgap reference and factory-trimmed resistor-divider networks for fixed-voltage monitoring (3.3V and 1.8V), while IN1 and IN4 accept external resistor dividers for adjustable thresholds down to 0.62V. Each comparator features built-in 0.3% threshold hysteresis and operates over full industrial temperature range.

All four PWRGD outputs are open-drain with 10µA internal pullup to VCC, enabling direct wire-OR connection without external components. An undervoltage lockout circuit forces all outputs low when VCC drops below 2.0V, ensuring deterministic behavior during brownout conditions.

Key Specifications

Pinout & Package

The MAX6709LUB+ is housed in a 10-pin µMAX package (3mm × 3mm, 0.5mm pitch), specified for surface-mount assembly and reflow-compatible processing. Pin 5 is GND; Pin 10 is VCC; Pins 1, 2, 3, and 4 are input terminals (IN1–IN4); Pins 6–9 are open-drain output terminals (PWRGD4–PWRGD1).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad voltage monitoring applications.

Compared with MAX6714DUB+, the MAX6709LUB+ delivers true quad independent PWRGD signaling ideal for rail-status arbitration; compared with TPS3307-33DGNR, it offers unmatched flexibility with two user-defined thresholds and broader voltage coverage-critical for heterogeneous multivoltage platforms.

Availability

The MAX6709LUB+ is available at Aetrix Electronics and suitable for telecommunications infrastructure, server board design, and notebook computer development requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for MAX6709LUB+ 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 high-performance analog, mixed-signal, and power-management ICs for industrial, computing, and communications markets.

The MAX6709LUB+ belongs to Maxim's precision voltage supervisor product line, engineered specifically for multivoltage system power integrity assurance in space- and power-constrained embedded platforms.

FAQ

What is the exact threshold voltage for the fixed 3.3V input on the MAX6709LUB+?

The MAX6709LUB+ has a fixed 3.3V input (IN2) with a -5% tolerance, resulting in a nominal trip threshold of 3.135V (3.3V × 0.95). Per the datasheet, the guaranteed range is 3.00V to 3.15V at TA = +25°C, with ±2.0% accuracy maintained across -40°C to +85°C. This matches JEDEC JESD8-12A specifications for 3.3V supply monitoring.

Can unused inputs on the MAX6709LUB+ be left floating?

No. Unused adjustable inputs (IN1 and IN4) on the MAX6709LUB+ must be connected to GND to prevent undefined comparator behavior and potential current leakage. Fixed inputs (IN2 and IN3) are internally terminated and may float safely, but grounding all unused pins is recommended for EMI robustness and noise immunity in production designs.

Does the MAX6709LUB+ support wire-OR connection of its PWRGD outputs?

Yes. All four PWRGD outputs on the MAX6709LUB+ are open-drain with 10µA internal pullup to VCC, explicitly designed for wire-OR configuration. When multiple PWRGD signals share a common pullup (e.g., to 3.3V), the combined output asserts low if any monitored rail fails-enabling single-point power-good status reporting without additional logic.

What is the minimum external resistor value allowed for adjusting the threshold on IN1 of the MAX6709LUB+?

The MAX6709LUB+ IN1 input has high impedance (>100MΩ), so external resistor values are constrained by power dissipation and noise immunity-not input loading. For a 0.62V internal reference, typical designs use R1 + R2 ≤ 1MΩ to limit divider current to <1µA. Values below 10kΩ are discouraged due to excessive current draw and reduced noise margin; 100kΩ–500kΩ is the recommended range per Maxim application notes.

How does the MAX6709LUB+ behave during VCC brownout below 2.0V?

When VCC drops below 2.0V, the MAX6709LUB+ activates its internal undervoltage lockout (UVLO) circuit, forcing all four PWRGD outputs low regardless of input voltage states. This behavior persists down to VCC = 1V (guaranteed from 0°C to +70°C), ensuring deterministic fail-safe signaling during power collapse and preventing spurious power-good assertions during recovery.