Analog Devices Inc./Maxim Integrated MAX808NCSA+

Overview

MAX808NCSA+ from Maxim Integrated is a precision +5V microprocessor supervisory circuit with battery switchover, low-line detection, and active-low RESET output. It features ±1.5% reset threshold accuracy (4.575V), 200ms reset timeout, 1µA standby current, and CMOS RAM write protection via CE gating. Used in portable/battery-powered equipment to ensure orderly shutdown and memory retention during brownout.

For engineers reviewing the MAX808NCSA+ datasheet, MAX808NCSA+ pinout, MAX808NCSA+ application, or MAX808NCSA+ equivalent, this page delivers verified functional context, validated pin roles, confirmed timing behavior (tRP = 200ms, tLL = 17µs), battery-switchover hysteresis (50mV), and CE propagation delay (3–8ns), all specific to the N-suffix 4.575V threshold variant in SO-8 package.

Technical Context

The MAX808NCSA+ integrates three independent comparators: reset (4.575V ±1.5%), low-line (4.627V rising, 52mV above reset), and battery switchover (VBATT vs. VCC). Its BiCMOS process enables tight voltage tolerance while maintaining 48µA typical supply current in normal operation and <1µA in battery-backup mode.

It implements a dedicated chip-enable (CE) gating path with 3ns min / 8ns max propagation delay (50Ω source, 50pF load), write-cycle completion hold (18µs), and CE OUT actively pulled to higher of VCC or VBATT when disabled - all designed to prevent CMOS RAM corruption during power failure.

Key Specifications

Pinout & Package

MAX808NCSA+ is housed in an 8-pin SO (Small Outline) package, RoHS-compliant with lead-free finish (+ suffix). Pin 1 is marked with a dot or beveled edge; device orientation follows JEDEC MS-012 standard.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX808NCSA+, MAX809SOT23+T reduces footprint but removes battery switchover and CE functionality essential for RAM retention; TPS3808G18DBVR offers threshold flexibility but lacks the deterministic 52mV low-line offset and write-cycle completion timing critical for legacy µP systems.

Availability

MAX808NCSA+ is available at Aetrix Electronics and suitable for portable medical monitors, industrial PLC controllers, handheld test instruments, and embedded automotive telematics requiring stable component supply with guaranteed long-term availability.

Supply support for MAX808NCSA+ 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, with emphasis on reliability and integration for demanding environments.

The MAX801/MAX808 product line was engineered specifically for microprocessor systems needing coordinated power monitoring, battery backup, and memory protection - targeting portable, industrial, and automotive applications where deterministic reset behavior and RAM integrity are non-negotiable.

FAQ

What is the exact reset threshold voltage of the MAX808NCSA+?

The MAX808NCSA+ has a nominal reset threshold of 4.575V with ±1.5% accuracy over temperature and supply variation. This value is fixed by the 'N' suffix and confirmed in the Electrical Characteristics table under VRST parameter for MAX80_N devices. The threshold remains stable across the -40°C to +85°C operating range with typical drift of <10mV.

Does the MAX808NCSA+ support battery backup for CMOS RAM?

Yes, the MAX808NCSA+ supports battery backup for CMOS RAM through its BATT and OUT pins. When VCC falls below both the reset threshold (4.575V) and VBATT, the internal PMOS switch connects BATT to OUT, supplying up to 20mA with ~12Ω on-resistance. The device guarantees RAM retention with <1µA battery standby current in backup mode.

How does the CE gating function work in the MAX808NCSA+?

The MAX808NCSA+ implements CE gating by passing CE IN to CE OUT during normal operation, then disabling the path when RESET asserts. Crucially, it holds CE OUT enabled for 18µs after VCC falls below the reset threshold to allow µP write-cycle completion. CE OUT is actively pulled to the higher of VCC or VBATT when disabled, preventing floating states.

Is the MAX808NCSA+ pin-compatible with other MAX80x variants?

Yes, the MAX808NCSA+ is pin-compatible with all MAX801/MAX808 variants in SO-8 and DIP-8 packages, including MAX808LCSA+, MAX808MCSA+, and MAX801NCSA+. Pin functions, electrical behavior, and timing parameters (e.g., 200ms tRP, 17µs tLL) are identical across the family - only reset threshold (L/N/M) and presence of watchdog (MAX801) differ.

What is the purpose of the LOWLINE output on the MAX808NCSA+?

The LOWLINE output on the MAX808NCSA+ is an active-low comparator that asserts when VCC rises to 4.627V (52mV above the 4.575V reset threshold). It provides a non-maskable interrupt (NMI) to the µP, enabling firmware to initiate data save, clock sync, or controlled shutdown before RESET activates - adding critical margin for graceful power-fail response.