Analog Devices Inc./Maxim Integrated MAX709TCUA

Overview

MAX709TCUA from Maxim Integrated is a precision power-supply monitor IC with active-low reset output, designed for +3.08V nominal supply systems. It asserts RESET when VCC falls below 3.00V (min), holds reset for 140ms (min) after VCC rises above threshold, operates down to 1.0V VCC, and draws only 35µA typical supply current. It is used in embedded microcontroller systems requiring reliable brownout detection and power-on reset.

For engineers reviewing the MAX709TCUA datasheet, MAX709TCUA pinout, MAX709TCUA application, or MAX709TCUA equivalent, key selection criteria include reset threshold accuracy (±1.5% over temperature), immunity to short VCC transients (<40µs at 100mV overdrive), guaranteed RESET state down to 1V VCC, and compatibility with 3.3V/3V µP interfaces without external components.

Technical Context

The MAX709TCUA integrates a precision voltage comparator with hysteresis, internal timing capacitor, and open-drain RESET driver. Its reset threshold is factory-trimmed to 3.08V (nominal), with ±1.5% initial accuracy and <0.02%/°C drift over –40°C to +85°C. The 140ms minimum reset timeout is generated by an on-chip RC network, independent of external components.

It features glitch-immune detection logic that ignores negative VCC transients ≤40µs when 100mV below threshold, and guarantees valid RESET output state (low or high-impedance) across full VCC range from 1.0V to 5.5V. No pull-up resistor is required for standard µP reset inputs.

Key Specifications

Pinout & Package

MAX709TCUA 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), pin numbering counterclockwise.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX709TCUA, MAX706TCSA provides identical electrical behavior in a larger, more manufacturable package, while TPS3808G30DBVR trades transient immunity and robustness for extreme quiescent current reduction-making MAX709TCUA optimal for cost-sensitive, noise-prone 3V systems needing proven reliability.

Availability

MAX709TCUA is available at Aetrix Electronics and suitable for industrial control systems, medical sensor nodes, automotive body electronics, and smart home gateways requiring stable component supply and long-term lifecycle support.

Supply support for MAX709TCUA 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, communications, and computing markets.

The MAX709 is part of Maxim's µP supervisory circuit family, engineered to replace discrete reset solutions in cost-sensitive, space-constrained embedded systems powered by 3V/3.3V/5V rails.

FAQ

What is the exact reset threshold voltage of the MAX709TCUA?

The MAX709TCUA has a nominal reset threshold of 3.08V, with a guaranteed range of 3.00V (min) to 3.15V (max) over the full operating temperature range (0°C to +70°C). This threshold is factory-trimmed and specified in the Electrical Characteristics table under "RESET Threshold, VTH" for suffix T. It is designed specifically for reliable supervision of 3.0V and 3.3V logic supplies.

Does the MAX709TCUA require an external pull-up resistor on the RESET pin?

Yes, the MAX709TCUA features an open-drain RESET output (pin 7), so an external pull-up resistor is required to establish a defined high-level voltage when RESET is inactive. A typical value is 10kΩ to VCC, though values from 4.7kΩ to 100kΩ are acceptable depending on bus capacitance and µP input leakage. No pull-up is needed if driving a dedicated reset input with internal pull-up.

Can the MAX709TCUA operate with a supply voltage below 3.0V?

Yes, the MAX709TCUA functions across VCC = 1.0V to 5.5V. Its RESET output remains valid (actively low or high-impedance) down to 1.0V, and it continues to monitor supply conditions. However, the 3.08V reset threshold means it will assert RESET whenever VCC drops below ~3.00V-even if VCC stays above 1.0V-ensuring early brownout detection in 3V systems.

How does the MAX709TCUA handle short negative transients on the VCC line?

The MAX709TCUA is designed to ignore short negative-going VCC transients: for example, it will not issue a reset pulse for transients ≤40µs duration when 100mV below the 3.08V threshold. This immunity is confirmed in the Typical Operating Characteristics graph "Maximum Transient Duration without Causing a Reset Pulse." A 0.1µF bypass capacitor at VCC (pin 2) further enhances this robustness.

Is the MAX709TCUA pin-compatible with other MAX709 variants like MAX709R or MAX709S?

No-while all MAX709 variants share identical pinout, package, and functional block diagram, the suffix (R/S/T/L/M) denotes different factory-set reset thresholds (e.g., 2.63V, 2.93V, 3.08V, etc.). MAX709TCUA is not pin-compatible with MAX709R or MAX709S in terms of electrical behavior: substituting them changes the reset point and may cause premature or delayed reset assertion. Always match the suffix to the target supply voltage.