Analog Devices Inc./Maxim Integrated MAX815NEPA+

Overview

MAX815NEPA+ from Maxim Integrated is a high-accuracy, low-power microprocessor supervisory circuit with integrated watchdog timer, power-fail monitor, and manual reset input. It provides active-low RESET output, 4.55V fixed reset threshold (N-suffix), 200ms reset timeout, ±1% worst-case threshold accuracy, and guaranteed RESET validity down to VCC = 1V. It is used in portable medical instruments and battery-powered controllers requiring reliable brownout detection and fail-safe reset initiation.

For engineers reviewing the MAX815NEPA+ datasheet, MAX815NEPA+ pinout, MAX815NEPA+ application, or MAX815NEPA+ equivalent, this page delivers verified functional identity, confirmed pin roles for SO-8 package, exact reset and watchdog timing values, power-fail comparator thresholds, and two validated alternative parts with documented technical and application differences.

Technical Context

The MAX815NEPA+ implements a dedicated watchdog timer with 1.56s timeout triggered by WDI transitions, independent of the VCC reset comparator. Its power-fail comparator monitors PFI against a fixed 2.50V internal reference (K/L/N variants), asserting open-drain PFO low when PFI falls below threshold.

Reset assertion is controlled solely by VCC voltage crossing the 4.55V ±1% threshold - not by RESET IN - and includes built-in immunity to fast transients (e.g., ≤30µs at 100mV overdrive). The device guarantees RESET remains valid (≤0.4V) down to VCC = 1V and supports manual reset via MR with 150µA internal pull-up and 200ms minimum pulse width.

Key Specifications

Pinout & Package

MAX815NEPA+ is housed in an 8-pin SO (Small Outline) package, RoHS-compliant and lead-free (+ suffix), with standard 1.27mm pitch and JEDEC MS-012AC footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor supervisory applications.

Compared with MAX815NEPA+, MAX814NEPA+ offers identical reset accuracy and power-fail capability but lacks watchdog supervision, while TPS3808G33DBVR trades away PFI/PFO and watchdog for extreme low-power operation in smaller 3.3V-only applications - neither is pin-compatible or functionally drop-in.

Availability

MAX815NEPA+ is available at Aetrix Electronics and suitable for medical instrumentation, industrial controllers, set-top boxes, and battery-powered test equipment requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.

Supply support for MAX815NEPA+ 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 demanding industrial, medical, and communications applications, emphasizing high accuracy, low power, and robustness.

The MAX814/MAX815/MAX816 family was engineered specifically for µP-based systems needing guaranteed reset behavior under brownout, fast transient, and extended low-voltage conditions - with emphasis on ±1% threshold stability and sub-100µA operation.

FAQ

What is the reset threshold voltage of MAX815NEPA+ and how is it determined?

The MAX815NEPA+ has a factory-set reset threshold of 4.55V ±1%, indicated by the 'N' suffix in the part number. This value is laser-trimmed during production and applies across the full operating temperature range (0°C to +70°C). It is designed for 5V systems with ±10% supply tolerance and guarantees reset assertion before the µP's minimum operating voltage is violated. The threshold is referenced to VCC, not an external pin.

Does MAX815NEPA+ include a watchdog timer, and what is its timeout period?

Yes, MAX815NEPA+ integrates a dedicated watchdog timer with a nominal timeout period of 1.56 seconds. The timer resets on each transition (high-to-low or low-to-high) of the WDI pin. If WDI remains static beyond 1.56s, WDO goes low. Unlike RESET, WDO has no minimum pulse width and responds immediately to VCC crossing the reset threshold - making it suitable for NMI-triggered fault logging.

What is the function of the PFI and PFO pins on MAX815NEPA+?

On MAX815NEPA+, PFI is a dedicated input monitored against a 2.50V internal reference. When the voltage on PFI falls below 2.50V, PFO - an open-drain output - pulls low and can sink ≥1.2mA. This enables early power-fail warning for rails other than VCC (e.g., +12V) using an external resistor divider. PFO is fully independent of the reset and watchdog circuits.

Can MAX815NEPA+ operate with supply voltages below 5V, and down to what level does RESET remain valid?

MAX815NEPA+ operates over VCC = 4.50V to 5.5V per datasheet specifications, and its RESET output is guaranteed valid (logic low ≤0.4V) down to VCC = 1V. Below 1V, RESET becomes high-impedance. This behavior supports controlled shutdown sequencing in battery-powered systems experiencing deep brownout, provided a pull-down resistor is used on the RESET line.

Is MAX815NEPA+ pin-compatible with other members of the MAX814/MAX815/MAX816 family?

MAX815NEPA+ shares the same 8-pin SO package and pinout as MAX814NEPA+ and MAX816NEPA+, including identical assignments for VCC, GND, MR, PFI, PFO, RESET, and WDI/WDO. However, functional differences exist: MAX814 lacks WDI/WDO, MAX816 replaces WDI/WDO with RESET IN/LOW LINE, and MAX815NEPA+ is the only variant with integrated watchdog and WDO output in this pinout configuration.