Analog Devices Inc./Maxim Integrated MAX816ESA+

Overview

MAX816ESA+ from Maxim Integrated is a ±1% accurate, low-power microprocessor supervisory circuit with adjustable reset threshold, active-high and active-low RESET outputs, power-fail monitoring (PFI/PFO), and manual reset input. It operates from 1.2V to 5.5V supply, guarantees valid RESET down to VCC = 1V, and draws only 75µA typical supply current - ideal for battery-powered medical instruments and portable controllers.

For engineers reviewing the MAX816ESA+ datasheet, MAX816ESA+ pinout, MAX816ESA+ application, or MAX816ESA+ equivalent, this page delivers verified electrical parameters, confirmed package mapping (8-pin SO), validated pin functions, real-world use cases in critical µP power monitoring, and two technically documented alternative parts with explicit functional and interface differences.

Technical Context

The MAX816ESA+ uses an external resistive divider on the RESET IN pin (1.700V internal reference) to set the reset threshold - unlike fixed-threshold MAX814/MAX815 variants. Its PFI comparator has a fixed 1.70V threshold and drives PFO as an open-drain output capable of sinking ≥1.2mA.

It provides dual RESET outputs: active-low RESET (pin 7) and active-high RESET (pin 8), both asserted for ≥140ms after VCC or RESET IN crosses threshold. No watchdog or low-line detector is present - distinguishing it from MAX814 (LOW LINE) and MAX815 (WDI/WDO).

Key Specifications

Pinout & Package

MAX816ESA+ is housed in an 8-pin SO (Small Outline) package, RoHS-compliant and lead-free (indicated by '+' suffix). Pin 1 is MR (Manual Reset Input), pin 2 is VCC, pin 3 is GND, pin 4 is PFI, pin 5 is PFO, pin 6 is RESET IN, pin 7 is RESET (active-low), and pin 8 is RESET (active-high).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX816ESA+, MAX814ESA+ provides VCC-based monitoring with low-line warning but cannot supervise external rails, while TLV809E33DBZR offers minimal functionality at lower price but omits all advanced features (PFI, MR, dual RESET) essential for robust embedded systems.

Availability

MAX816ESA+ is available at Aetrix Electronics and suitable for medical equipment, industrial controllers, portable diagnostic tools, and battery-powered data loggers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX816ESA+ 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.

The MAX814/MAX815/MAX816 family targets high-reliability microprocessor supervision with ±1% reset accuracy, ultra-low quiescent current, and flexible monitoring architectures - specifically engineered for systems where power integrity directly impacts safety or data integrity.

FAQ

What is the function of the RESET IN pin on the MAX816ESA+?

The RESET IN pin on the MAX816ESA+ is a high-impedance input (≤35nA leakage) referenced to an internal 1.700V comparator. It accepts a divided-down version of the supply rail being monitored - enabling precise, user-adjustable reset thresholds. When the voltage on RESET IN falls below 1.700V, the MAX816ESA+ asserts both RESET outputs for ≥140ms. This architecture decouples reset triggering from VCC, allowing supervision of auxiliary rails like +3.3V, +2.5V, or even negative supplies.

Does the MAX816ESA+ include a watchdog timer?

No, the MAX816ESA+ does not include a watchdog timer. That function is exclusive to the MAX815 variant (which features WDI and WDO pins). The MAX816ESA+ is optimized for adjustable-supply monitoring and power-fail warning, omitting watchdog circuitry to reduce complexity and cost. If watchdog functionality is required, MAX815ESA+ or MAX816's sibling parts must be selected instead - the MAX816ESA+ itself provides no timeout or transition-detection capability.

Can the MAX816ESA+ monitor a negative voltage rail?

Yes, the MAX816ESA+ can monitor a negative rail using the PFI input. By connecting the negative supply through a resistor divider to PFI (with appropriate polarity referencing), the 1.70V internal reference enables detection of degradation - e.g., –12V falling toward –10V. When PFI voltage drops below 1.70V, PFO goes low, which can be inverted and fed to MR to assert RESET. This technique is documented in Maxim's application notes and requires careful biasing to ensure PFI stays within absolute maximum ratings relative to GND.

What is the minimum VCC required for the MAX816ESA+ to guarantee valid RESET output?

The MAX816ESA+ guarantees valid RESET output down to VCC = 1V. Below 1V, the RESET outputs become high-impedance and no longer drive logic levels - though the internal comparators remain functional until VCC drops further. For reliable operation across full brownout, designers should ensure that downstream logic inputs tied to RESET have appropriate pull-downs (e.g., 100kΩ to GND) to prevent floating states when VCC < 1V. This behavior is explicitly characterized in the Electrical Characteristics table under "RESET Output Voltage" conditions.

How do I calculate resistor values for the RESET IN divider on the MAX816ESA+?

To set a desired reset threshold VRT on the MAX816ESA+, use the formula: VRT = VRIT × (1 + R1/R2), where VRIT = 1.700V. Choose R2 first (e.g., 100kΩ), then solve for R1 = R2 × (VRT/VRIT – 1). For example, to trigger reset at 3.30V: R1 = 100kΩ × (3.30/1.70 – 1) ≈ 94.1kΩ. Use 0.1% tolerance resistors to achieve ±1.2% overall threshold accuracy. Ensure total divider current remains <100nA to avoid loading the high-Z input - R1+R2 should typically exceed 1MΩ.