Analog Devices Inc./Maxim Integrated MAX815NESA+

Overview

MAX815NESA+ from Maxim Integrated is a high-accuracy, low-power microprocessor supervisory circuit with integrated watchdog timer, power-fail monitoring, and manual reset functionality. It features a 4.55V ±1% reset threshold, 200ms reset pulse width, 75µA max supply current, and guaranteed RESET validity down to VCC = 1V. It is used in portable/battery-powered equipment for reliable µP reset during brownout, power-up, and software fault conditions.

For engineers reviewing the MAX815NESA+ datasheet, MAX815NESA+ pinout, MAX815NESA+ application, or MAX815NESA+ equivalent, key selection criteria include reset threshold accuracy (±1%), watchdog timeout (1.56s), power-fail comparator reference (2.50V), low-line immunity, and SO-8 package compatibility with legacy DIP footprints.

Technical Context

The MAX815NESA+ implements a dedicated watchdog timer with independent 1.56s timeout, triggered by WDI transitions - not VCC monitoring. Its reset generator uses a precision bandgap reference to achieve ±1% worst-case threshold accuracy across temperature and supply variation.

It integrates a power-fail comparator referenced to 2.50V (for K/L/N suffixes), a manual reset input with 150µA internal pullup, and active-low RESET output. Unlike the MAX814/MAX816, it lacks LOW LINE output and adjustable reset input, distinguishing its functional scope within the family.

Key Specifications

Pinout & Package

MAX815NESA+ is housed in an 8-pin SO (Small Outline) package, RoHS-compliant and lead-free (denoted by '+' suffix), with 1.27mm pitch and standard JEDEC MS-012AC footprint compatible with automated SMT assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX815NESA+, MAX814NESA+ offers complementary timing signaling but no software fault coverage, while TPS3808G33DBVR trades watchdog capability and voltage range for extreme current efficiency and smaller footprint - making MAX815NESA+ the only option among the three supporting both precise +5V supervision and autonomous firmware recovery.

Availability

MAX815NESA+ is available at Aetrix Electronics and suitable for portable medical devices, industrial PLC modules, smart energy meters, and point-of-sale terminals requiring stable component supply with long-term lifecycle support.

Supply support for MAX815NESA+ 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 analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX814/MAX815/MAX816 family was designed specifically for high-reliability microprocessor supervision in battery-powered and noise-prone environments, emphasizing ±1% threshold accuracy, glitch immunity, and low quiescent current.

FAQ

What is the reset threshold voltage of the MAX815NESA+?

The MAX815NESA+ has a factory-set reset threshold of 4.55V ±1%, optimized for +5V systems with ±10% supply tolerance. This value is fixed by the 'N' suffix and verified across -40°C to +85°C. The threshold ensures reset assertion before critical µP operation fails, and is distinct from the 2.50V power-fail comparator reference used on the PFI pin. MAX815NESA+ does not support adjustable reset thresholds like the MAX816.

Does the MAX815NESA+ include a watchdog timer?

Yes, the MAX815NESA+ integrates a dedicated watchdog timer with a nominal 1.56s timeout period, monitored via the WDI pin. Unlike VCC-based reset, this timer operates independently and triggers WDO low upon timeout - enabling detection of software hangs even if the power supply remains stable. The MAX815NESA+ is the only member of the MAX814/815/816 family with this feature; MAX814 and MAX816 omit it entirely.

What package type and RoHS status does the MAX815NESA+ have?

The MAX815NESA+ is supplied in an 8-pin SO (Small Outline) package, compliant with JEDEC MS-012AC dimensions and 1.27mm lead pitch. The '+' suffix explicitly denotes lead-free, RoHS-compliant construction per Maxim's ordering convention. It is pin-compatible with the through-hole 8-pin PDIP variant (e.g., MAX815NPA) but requires SMT reflow processing.

How does the MAX815NESA+ handle power supply transients?

The MAX815NESA+ rejects fast negative-going VCC transients up to 30µs in duration when the overdrive is 100mV below the 4.55V reset threshold, as characterized in the Typical Operating Characteristics. This immunity is achieved via internal filtering and comparator hysteresis, preventing spurious resets in electrically noisy environments such as motor drives or switching power supplies - a key differentiator from basic reset ICs.

Can the MAX815NESA+ monitor voltages other than VCC?

Yes, the MAX815NESA+ can monitor auxiliary rails using its PFI pin: connect a resistive divider from the target voltage (e.g., +12V or +3.3V) to PFI so that the divided voltage crosses 2.50V just before the rail becomes unsafe. When PFI drops below 2.50V, PFO asserts to signal the µP. This technique is documented in Figure 11 of the datasheet and requires no additional components beyond the divider resistors.