Analog Devices Inc./Maxim Integrated MAX815TESA+

Overview

MAX815TESA+ from Maxim Integrated is a ±1% accurate, low-power microprocessor supervisory circuit with integrated watchdog timer, power-fail monitoring, and manual reset functionality. It features a 4.7V reset threshold (T-suffix = 3.03V), 1.56s watchdog timeout, active-low RESET output, and guaranteed operation down to VCC = 1V. Designed for portable/battery-powered equipment requiring reliable brownout detection and fail-safe µP reset control.

For engineers reviewing the MAX815TESA+ datasheet, MAX815TESA+ pinout, MAX815TESA+ application, or MAX815TESA+ equivalent, this device delivers verified ±1% reset threshold accuracy, glitch-immune reset assertion, 75µA supply current, and validated watchdog timing - critical for medical instruments, intelligent controllers, and set-top boxes where deterministic power sequencing and fault recovery are mandatory.

Technical Context

The MAX815TESA+ implements a dedicated watchdog timer with 1.56s timeout and WDI transition detection logic, independent of the VCC reset comparator. Its power-fail monitor compares PFI against a fixed 1.70V internal reference (T-suffix and MAX816), enabling early warning before VCC collapse.

Reset generation uses a precision bandgap-based comparator with 60mV hysteresis relative to the reset threshold, and the RESET output remains valid down to VCC = 1V with guaranteed VOL ≤ 0.4V at ISINK = 50µA. The manual reset input (MR) includes a 150µA internal pullup and supports TTL/CMOS logic levels.

Key Specifications

Pinout & Package

MAX815TESA+ is housed in an 8-pin SO (Small Outline) package with gull-wing leads, RoHS-compliant and lead-free (+ suffix). Pin pitch is 1.27mm; body dimensions are 4.9mm × 6.0mm × 1.75mm (JEDEC MS-012).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX815TESA+, MAX814TESA+ removes watchdog capability but adds low-line detection for early brownout signaling, while TPS3808G33DBVR trades integrated fault-monitoring features for ultra-low quiescent current - making MAX815TESA+ the only option supporting both deterministic reset and autonomous software supervision in a single 8-pin SO package.

Availability

MAX815TESA+ is available at Aetrix Electronics and suitable for medical equipment, intelligent instruments, set-top boxes, portable/battery-powered equipment, and critical µP power monitoring requiring stable component supply across industrial temperature range (-40°C to +85°C).

Supply support for MAX815TESA+ 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 was engineered specifically for high-reliability µP supervision in portable and mission-critical systems, emphasizing ±1% reset accuracy, ultra-low supply current, and integrated fault-detection functions.

FAQ

What is the reset threshold voltage of the MAX815TESA+?

The MAX815TESA+ has a factory-set reset threshold of 3.03V ±1%, optimized for +3.3V supply monitoring. This value is fixed by the 'T' suffix and confirmed in the Electrical Characteristics table for +3V parts. The threshold remains stable across -40°C to +85°C and ensures reset assertion before the monitored rail falls below the minimum operating voltage of most 3.3V microcontrollers. The MAX815TESA+ does not support adjustable reset thresholds - that function is exclusive to the MAX816 variant.

Does the MAX815TESA+ include a watchdog timer?

Yes, the MAX815TESA+ integrates a dedicated watchdog timer with a nominal timeout period of 1.56 seconds. It monitors the WDI pin for transitions and asserts WDO low if WDI remains static (high or low) beyond this interval. Unlike the reset comparator, the watchdog operates independently of VCC level and remains functional as long as VCC is above 1.0V. This feature is explicitly documented in the Selector Table and Detailed Description section for MAX815 devices.

What is the function of the PFI and PFO pins on the MAX815TESA+?

On the MAX815TESA+, the PFI (Power-Fail Input) pin is compared to a fixed 1.70V internal reference. When the voltage on PFI falls below 1.70V, the PFO (Power-Fail Output) pin goes low (active-low, open-drain). This allows early warning of supply degradation before the main reset threshold is crossed. For a +3.3V system, a resistor divider from VCC to GND sets PFI to ~1.70V at the desired warning point - e.g., when VCC reaches ~3.1V. This behavior is confirmed in the Pin Description and Applications Information sections.

Can the MAX815TESA+ operate with VCC below 3.0V?

Yes, the MAX815TESA+ guarantees functional RESET output down to VCC = 1.0V, with RESET remaining a valid logic low (≤0.4V) until VCC drops below that level. However, the reset comparator itself requires VCC ≥ 1.2V to assert RESET reliably during brownout, and the watchdog timer requires VCC ≥ 1.0V to maintain timing accuracy. These limits are specified in Absolute Maximum Ratings and Electrical Characteristics tables for +3V parts, and apply directly to the MAX815TESA+.

Is the MAX815TESA+ pin-compatible with other devices in the MAX814/MAX815/MAX816 family?

Yes, the MAX815TESA+ shares identical 8-pin SO (and DIP) pinout with MAX814 and MAX816 variants, including MR, VCC, GND, PFI, PFO, WDI (or LOW LINE/RESET IN), RESET, and WDO (or RESET). Pin functions are fully documented in the Pin Configuration diagrams and Pin Description table. This mechanical and electrical compatibility allows drop-in replacement within the same package footprint, though functional differences (e.g., presence of watchdog or adjustable threshold) must be verified per application requirements.