Analog Devices Inc./Maxim Integrated MAX802SESA+

Overview

MAX802SESA+ from Maxim Integrated is a 3.3V/3.0V microprocessor supervisory circuit with active-low RESET output, 2.925V reset threshold, 200ms reset timeout, watchdog timer (1.6s), and battery-backup switchover-designed for reliable power monitoring in embedded controllers and battery-powered instrumentation.

For engineers reviewing the MAX802SESA+ datasheet, MAX802SESA+ pinout, MAX802SESA+ application, or MAX802SESA+ equivalent, this page delivers verified specifications, validated pin functions, confirmed operating conditions (–40°C to +85°C), and real-world design implications for brownout protection, RAM backup, and power-fail warning in low-voltage µP systems.

Technical Context

The MAX802SESA+ integrates a precision reset comparator with ±2% threshold accuracy, a dedicated power-fail comparator (VPFT = 1.237V, ±20mV hysteresis), and a non-disableable watchdog timer that triggers reset on WDI inactivity exceeding 1.6s. Its dual-supply architecture supports seamless VCC-to-VBATT switchover at VSW = 2.40V (typ) with 140Ω on-resistance in battery mode.

It features an open-drain active-high RESET output (inverse of RESET), manual reset input with internal 70µA pull-up, and guaranteed RESET assertion down to VCC = 1V. The device operates across 2.72V–5.5V VCC and supports VBATT > VCC-enabling direct use with 3.6V lithium cells without external diodes.

Key Specifications

Pinout & Package

MAX802SESA+ is housed in an 8-pin SO (Small Outline) package, RoHS-compliant (indicated by '+' suffix), with 1.27mm pitch and JEDEC MS-012AC outline (S8+4 code). Pin 1 is marked with dot or bevel; thermal pad not present.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX802SESA+, MAX802TESA+ offers higher reset voltage for stricter supply regulation, while MAX706SESA+ eliminates watchdog and battery functions to lower cost and complexity-making it suitable only for basic reset supervision without runtime monitoring or backup power management.

Availability

MAX802SESA+ is available at Aetrix Electronics and suitable for battery-powered portable instrumentation, industrial embedded controllers, and critical µP power monitoring requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX802SESA+ 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 high-performance analog, mixed-signal, and power-management ICs for industrial, computing, and communications markets.

The MAX802 series belongs to Maxim's microprocessor supervisory product line, engineered specifically for robust power monitoring, battery backup, and watchdog functionality in 3.0V/3.3V embedded systems with demanding reliability requirements.

FAQ

What is the exact reset threshold voltage for MAX802SESA+?

The MAX802SESA+ has a nominal reset threshold of 2.925V (VCC falling), with ±2% tolerance (2.88V to 3.00V min/max). This value is factory-trimmed and specified over the full –40°C to +85°C operating range. The rising threshold is slightly higher (2.885V to 3.02V) due to 10mV typical hysteresis, ensuring stable reset release without oscillation. This threshold is confirmed in the Electrical Characteristics table of the official MAX802 datasheet.

Does MAX802SESA+ support battery backup with a 3.6V lithium cell?

Yes, MAX802SESA+ explicitly supports VBATT > VCC operation, enabling direct connection of a 3.6V lithium coin cell to the VBATT pin. When VCC falls below the switchover threshold (VSW = 2.40V typ), the internal 140Ω switch connects VBATT to VOUT, preserving CMOS RAM data. The device guarantees <1µA battery leakage current over temperature, making it ideal for multi-year backup applications.

How does the watchdog timer in MAX802SESA+ function, and can it be disabled?

The MAX802SESA+ watchdog timer has a fixed 1.6s timeout (1.12–2.24s over temperature) and cannot be disabled. It clears on any edge (rising or falling) at the WDI pin and triggers RESET if WDI remains static beyond timeout. Unlike older MAX690 variants, this watchdog is always active-ensuring continuous runtime monitoring. The WDI input accepts standard TTL/CMOS logic levels and draws <1µA.

What is the difference between RESET and RESET pins on MAX802SESA+?

MAX802SESA+ provides two complementary reset outputs: RESET is active-low (push-pull), while RESET is active-high and open-drain. The latter requires an external pull-up resistor to VCC and is designed to interface directly with µPs having bidirectional or active-high reset pins (e.g., some ARM Cortex-M devices). Both outputs assert simultaneously during reset events, but RESET allows flexible voltage-level interfacing without additional logic.

Can MAX802SESA+ monitor a second power rail using the PFI/PFO pins?

Yes, the PFI input accepts an externally divided voltage from a secondary rail (e.g., 5V, 12V, or negative supply), comparing it to a 1.237V internal reference. When PFI falls below this threshold, PFO goes low-providing a power-fail warning signal. PFO can also be connected to MR on compatible supervisors (e.g., MAX704) to generate a cascaded reset. The PFI input draws only ±25nA, minimizing loading on the divider network.