Analog Devices Inc./Maxim Integrated MAX709LEPA+

Overview

MAX709LEPA+ from Maxim Integrated is a precision power-supply monitor IC with active-low reset output, designed for +5V systems requiring 4.65V reset threshold, 140ms minimum power-on delay, and operation from -40°C to +85°C. It provides reliable µP reset during power-up, brownout, and power-down events in embedded controllers and industrial microprocessor systems.

For engineers reviewing the MAX709LEPA+ datasheet, MAX709LEPA+ pinout, MAX709LEPA+ application, or MAX709LEPA+ equivalent, key selection criteria include guaranteed RESET state down to VCC = 1V, immunity to short negative VCC transients ≤40µs, low 65µA supply current at +85°C, and compatibility with 8-pin plastic DIP packaging.

Technical Context

The MAX709LEPA+ integrates a precision voltage comparator with hysteresis, internal timing capacitor, and open-drain RESET driver. Its reset threshold is fixed at 4.65V ±150mV over temperature, and it guarantees a minimum 140ms reset timeout after VCC rises above threshold.

It operates across full VCC range (1.0V–5.5V), maintains RESET validity down to VCC = 1V, and features transient immunity against negative-going VCC glitches up to 100mV overdrive for durations under 40µs - critical for noisy industrial power rails.

Key Specifications

Pinout & Package

MAX709LEPA+ is supplied in an 8-pin plastic DIP package (0.300" wide) with standard through-hole footprint. Pin 1 is top-left corner when notch faces up; pins numbered counterclockwise.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX706PEPA+, MAX709LEPA+ eliminates MR complexity and cost while retaining identical reset behavior; versus TPS3808G33DBVR, it provides higher threshold accuracy for +5V rails and through-hole manufacturability - critical for high-reliability industrial repair and long-lifecycle programs.

Availability

MAX709LEPA+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic equipment, automotive body control modules, and energy metering gateways requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX709LEPA+ 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, automotive, and communications markets.

The MAX709 belongs to Maxim's µP supervisory circuit product line, engineered specifically to replace discrete reset solutions in cost-sensitive, reliability-critical microprocessor systems with minimal external components.

FAQ

What is the exact reset threshold voltage for MAX709LEPA+?

The MAX709LEPA+ has a nominal reset threshold of 4.65V, with a guaranteed range of 4.50V to 4.75V over the full -40°C to +85°C operating temperature range. This value is factory-trimmed and does not require external calibration. The 'L' suffix in MAX709LEPA+ explicitly denotes the 4.65V version per Maxim's ordering guide.

Does MAX709LEPA+ require an external pull-up resistor on the RESET pin?

Yes, MAX709LEPA+ features an open-drain RESET output and requires an external pull-up resistor (typically 10kΩ to VCC) to establish a defined high state when not actively asserting reset. Without it, the RESET line floats and cannot reliably drive microprocessor reset inputs. The datasheet confirms this in the "Pin Description" and "Typical Operating Circuit" sections.

Can MAX709LEPA+ operate with VCC below 3.0V?

Yes, MAX709LEPA+ functions down to VCC = 1.0V, and its RESET output remains asserted (low) until VCC exceeds 4.50V. However, the device does not actively drive RESET below 1.0V - it becomes high-impedance. For applications requiring valid RESET down to 0V, a 100kΩ pull-down resistor is recommended per Maxim's Applications Information section.

Is MAX709LEPA+ pin-compatible with other MAX709 variants like MAX709CEPA+?

Yes, all MAX709 variants including MAX709LEPA+ share identical 8-pin DIP pinout and terminal assignments - only the reset threshold voltage and temperature grade differ. The 'L' (4.65V, -40°C to +85°C) and 'C' (4.65V, 0°C to +70°C) versions are mechanically and electrically interchangeable in the same socket, provided ambient temperature stays within the 'C' grade limit.

What is the maximum allowable negative VCC transient duration that will not trigger a false reset on MAX709LEPA+?

Per Figure 1 in the MAX709 datasheet, a negative-going VCC transient of 100mV below the 4.65V threshold (i.e., to 4.55V) will not cause a false reset if its duration is ≤40µs at +25°C. This immunity decreases with larger overdrive magnitudes and increases slightly at lower temperatures - confirming robustness in electrically noisy industrial settings.