Analog Devices Inc./Maxim Integrated MAX808MESA

Overview

MAX808MESA from Maxim Integrated is a precision +5V microprocessor supervisory IC providing reset generation, low-line warning, and battery-backed CMOS RAM write protection. It features ±1.5% reset threshold accuracy (4.425V), 200ms reset timeout, and integrated chip-enable gating with 3ns propagation delay. Used in portable/battery-powered equipment to ensure orderly shutdown and memory integrity during brownout.

For engineers reviewing the MAX808MESA datasheet, MAX808MESA pinout, MAX808MESA application, or MAX808MESA equivalent, this page delivers verified functional context, validated pin roles, confirmed timing behavior under VCC fall/rise, and real-world design implications of its CE gating and battery switchover architecture.

Technical Context

The MAX808MESA implements three independent comparators: reset (4.425V threshold), low-line (4.477V rising, 52mV above reset), and battery switchover (VBATT vs. VCC). Its internal timer guarantees 200ms RESET assertion after VCC rises above threshold or after power failure detection.

Unlike the MAX801, the MAX808MESA omits watchdog functionality but adds active chip-enable gating: CE IN controls CE OUT with automatic 18µs write-cycle completion hold, and CE OUT is actively pulled high to the higher of VCC or VBATT when disabled. All outputs swing rail-to-rail between VCC/GND.

Key Specifications

Pinout & Package

MAX808MESA is housed in an 8-pin SO (Small Outline) package, RoHS-compliant, with standard JEDEC MS-012AC footprint (5.0mm × 4.0mm, 1.27mm pitch).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX808MESA, MAX809MESA reduces cost and complexity but sacrifices LOWLINE warning, CE-controlled write completion, and battery-backed RAM support; TPS3808G33DBVR offers tighter 0.5% threshold tolerance at 3.3V but cannot replace MAX808MESA in +5V battery-switchover applications.

Availability

MAX808MESA is available at Aetrix Electronics and suitable for portable medical devices, industrial PLC controllers, smart energy meters, and avionics data recorders requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX808MESA 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 power, sensing, and interface applications in industrial, automotive, and computing markets.

The MAX808MESA belongs to Maxim's µP supervisory product line, engineered specifically for +5V systems needing deterministic reset, battery-backed memory protection, and fail-safe write-cycle completion in harsh or battery-constrained environments.

FAQ

What is the exact reset threshold voltage of the MAX808MESA?

The MAX808MESA has a nominal reset threshold of 4.425V with ±1.5% accuracy over temperature. This value is factory-trimmed and specified across the full -40°C to +85°C operating range. The 'M' suffix in MAX808MESA explicitly denotes this 4.425V threshold variant, distinct from the 4.575V (N) and 4.675V (L) versions. The threshold remains stable with minimal drift versus temperature, as confirmed in the RESET THRESHOLD vs. TEMPERATURE graph (Figure MAX801/808-07).

Does the MAX808MESA provide watchdog functionality like the MAX801?

No, the MAX808MESA does not include a watchdog timer. Watchdog functionality is exclusive to the MAX801 family (e.g., MAX801MESA). The MAX808MESA is optimized for memory protection and power monitoring only, adding chip-enable gating and battery switchover-but omitting WDI input, watchdog timeout logic, and associated timing circuitry. This architectural difference is clearly stated in the General Description and Functional Diagram sections of the datasheet.

How does the CE gating in MAX808MESA prevent corrupted RAM writes during power failure?

The MAX808MESA holds CE OUT active for exactly 18µs after RESET assertion begins, allowing the µP to complete its current memory write cycle even as VCC collapses. If the write finishes within that window, CE OUT goes high immediately; if not, it goes high at the 18µs mark. This behavior is implemented in hardware and requires no firmware intervention. The CE IN pin becomes high-impedance during this period, isolating the µP from bus contention.

Can MAX808MESA operate with a SuperCap™ or MaxCap™ as the backup source?

Yes, the MAX808MESA is explicitly designed for MaxCap™/SuperCap™ compatibility. Its battery switchover comparator includes hysteresis (typically +0.05V on rising VCC) that accommodates slow-charging supercapacitors. The device tolerates VBATT up to 5.5V and draws only ≤1µA in backup mode, making it ideal for 0.47F-based backup solutions-as demonstrated in Figure 8 of the datasheet using a 1N4148 and 0.47F capacitor.

What is the function of the LOWLINE output on the MAX808MESA?

The LOWLINE output is an active-low CMOS signal that asserts when VCC falls to 4.477V (52mV above the 4.425V reset threshold). It serves as a non-maskable interrupt (NMI) to trigger firmware-controlled shutdown routines-such as saving volatile data or disabling peripherals-before RESET activates. Its 13mV hysteresis prevents chatter during slow VCC decay, and its propagation delay is tightly specified at 17µs (VCC falling).