Analog Devices Inc./Maxim Integrated MAX709TCPA

Overview

MAX709TCPA from Maxim Integrated is a precision power-supply monitor IC with active-low reset output, designed for +3.3V and +3V systems. It asserts RESET when VCC falls below 3.08V (±2% tolerance), holds reset for ≥140ms after VCC recovers, operates down to 1.0V supply, consumes only 35µA typical supply current, and is housed in an 8-pin plastic DIP package. It enables reliable microprocessor supervision in low-voltage embedded controllers.

For engineers reviewing the MAX709TCPA datasheet, MAX709TCPA pinout, MAX709TCPA application, or MAX709TCPA equivalent, key selection criteria include reset threshold accuracy (3.08V), guaranteed minimum reset timeout (140ms), ultra-low quiescent current (35µA), immunity to short VCC transients (<40µs at 100mV overdrive), and compatibility with 3V/3.3V µP reset inputs requiring valid low-state assertion down to VCC = 1V.

Technical Context

The MAX709TCPA integrates a precision voltage comparator with hysteresis, internal timing capacitor, and open-drain RESET driver. Its reset threshold is factory-trimmed to 3.08V (T suffix) with ±2% initial accuracy and <0.0003%/°C temperature coefficient, ensuring stable brownout detection across -40°C to +85°C.

It delivers a monotonic, glitch-free reset pulse on power-up and power-down without external components. The RESET output remains valid (low) until VCC exceeds 3.08V and sustains the active state for ≥140ms, independent of VCC slew rate up to 100V/µs.

Key Specifications

Pinout & Package

MAX709TCPA is supplied in an 8-pin plastic DIP (dual in-line package) with 0.3-inch body width and through-hole mounting. Pin 1 is top-left corner (notch side), pin numbering proceeds counterclockwise.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX709TCPA, MAX706RPA offers identical functionality at lower cost but sacrifices industrial temperature range, while MAX708TSA provides the same performance in a smaller SO-8 package-enabling higher-density layouts but eliminating through-hole assembly flexibility.

Availability

MAX709TCPA is available at Aetrix Electronics and suitable for industrial PLC controllers, medical sensor nodes, and automotive body control modules requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for MAX709TCPA 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 power management, sensing, and interface applications, with emphasis on high-reliability industrial and automotive solutions.

The MAX709 series was developed specifically for microprocessor supervisory functions in 3V/3.3V/5V systems, delivering integrated reset generation with minimal external components and guaranteed timing behavior across temperature.

FAQ

What is the exact reset threshold voltage of the MAX709TCPA?

The MAX709TCPA has a factory-trimmed nominal reset threshold of 3.08V with ±2% initial accuracy over temperature. This value is specified in the Electrical Characteristics table under "RESET Threshold, VTH" for suffix T, and applies across the full -40°C to +85°C operating range. The MAX709TCPA will assert RESET when VCC falls below this threshold and maintain it until VCC rises above 3.08V and sustains the active state for ≥140ms.

Does the MAX709TCPA require external components to function?

No, the MAX709TCPA operates autonomously with no external components required for basic reset functionality. It integrates the voltage reference, comparator, timing circuitry, and output driver. A 0.1µF ceramic bypass capacitor is recommended at the VCC pin (pin 2) to improve immunity to fast VCC transients, but this is a layout best practice-not a functional requirement for reset assertion.

Can the MAX709TCPA drive a microprocessor reset pin directly?

Yes, the MAX709TCPA RESET output (pin 7) is an open-drain driver capable of sinking up to 20mA, making it compatible with standard µP reset inputs. An external pull-up resistor (typically 10kΩ to VCC) is required to establish the high state. For µPs with bidirectional reset pins (e.g., Motorola 68HC11), a 4.7kΩ series resistor between MAX709TCPA RESET and the µP pin prevents contention.

What is the minimum VCC voltage at which the MAX709TCPA guarantees correct RESET output state?

The MAX709TCPA guarantees correct RESET output state down to VCC = 1.0V. Below 1.0V, the RESET output becomes high-impedance (open-circuit). For applications requiring valid RESET down to 0V, a pull-down resistor (e.g., 100kΩ) on the RESET line ensures the signal remains low during deep undervoltage. This behavior is explicitly documented in the Applications Information section of the MAX709TCPA datasheet.

How does the MAX709TCPA handle short negative transients on the VCC line?

The MAX709TCPA is designed to ignore short negative-going VCC transients. Specifically, it will not generate a spurious reset pulse for transients ≤40µs duration that dip up to 100mV below the 3.08V threshold. This immunity is achieved via internal filtering and comparator hysteresis. Layout practices-including placing a 0.1µF bypass capacitor close to pin 2 (VCC)-further enhance robustness against such noise events in the MAX709TCPA application.