Analog Devices Inc./Maxim Integrated MAX820MCSE+

Overview

MAX820MCSE+ from Maxim Integrated is a microprocessor supervisory circuit with ±2% reset and low-line threshold accuracy, 200ms power-up reset delay, and integrated watchdog timer with programmable timeout (1.6s nominal). It provides active-low/high reset outputs, manual reset input, chip-enable gating, and overvoltage detection - designed for critical µP power monitoring in industrial controllers and embedded systems.

For engineers reviewing the MAX820MCSE+ datasheet, MAX820MCSE+ pinout, MAX820MCSE+ application, or MAX820MCSE+ equivalent, this page delivers verified functional identity, validated pin roles, confirmed timing behavior (200ms reset delay, 70ns WDPO-to-WDO skew), exact threshold accuracy (±2%), and real-world memory write-cycle protection capability.

Technical Context

The MAX820MCSE+ implements dual-comparator supervision: one for reset assertion at a factory-set 4.37V threshold (±2% accuracy), another for low-line warning 120mV above that threshold. Its watchdog function monitors WDI transitions and asserts WDPO (500µs pulse) followed by WDO (latched low) after timeout - with SWT pin enabling capacitor-programmable timing (k=16.2 @ 5V).

It integrates a bidirectional CE transmission gate (10ns max propagation delay) that disables during reset to prevent RAM corruption, plus an uncommitted overvoltage comparator (OVI/OVO) with 1.30V reference and 55µs propagation delay. RESET remains valid down to VCC = 1V, and MR accepts TTL/CMOS logic or momentary switch inputs with 12µs propagation delay.

Key Specifications

Pinout & Package

MAX820MCSE+ is housed in a 16-pin narrow SOIC (SO) package, 3.9mm width, RoHS-compliant lead-free construction (indicated by '+' suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX792MCSE+, the MAX820MCSE+ delivers tighter threshold tolerance for deterministic brownout response, while TPS3823MPDBVR offers higher accuracy at lower integration - making MAX820MCSE+ optimal for systems requiring coordinated NMI + reset + watchdog + CE control in one IC.

Availability

MAX820MCSE+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic instruments, telecom base station management, and automotive infotainment head units requiring stable component supply across extended product lifecycles.

Supply support for MAX820MCSE+ 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 connectivity applications - with emphasis on reliability and performance in harsh environments.

The MAX820MCSE+ belongs to Maxim's microprocessor supervisory circuit family, engineered specifically for deterministic power-up sequencing, brownout resilience, and fail-safe memory protection in mission-critical embedded systems.

FAQ

What is the exact reset threshold voltage for MAX820MCSE+ and how is it specified?

The MAX820MCSE+ has a nominal reset threshold voltage of 4.37V with ±2% accuracy over the 0°C to +70°C operating range. This value is factory-trimmed and guaranteed - not typical - and applies specifically to the 'M' suffix variant. The threshold remains valid down to VCC = 1V, ensuring reliable reset assertion even during deep brownout conditions. This specification is documented in the Electrical Characteristics table of the MAX792/MAX820 datasheet Rev. 4.

Does MAX820MCSE+ support external programming of reset and low-line thresholds?

Yes, the MAX820MCSE+ supports external programming via the RESET IN/INT and LLIN/REFOUT pins. When RESET IN/INT is biased above 600mV, the internal voltage divider disconnects and both comparators accept externally set thresholds using a resistor divider network. This allows customization of reset and low-line points to match specific power supply tolerances - a capability confirmed in the "External Programming Mode" section of the MAX792/MAX820 datasheet.

How does the watchdog function behave on MAX820MCSE+, and what is the role of WDPO?

The MAX820MCSE+ watchdog monitors WDI transitions and asserts WDPO (a 500–1700µs low pulse) 70ns before WDO goes low on timeout. WDPO is designed to clock an external D flip-flop - enabling two-fault latching for hardware shutdown. Unlike simple timeout indicators, WDPO provides advance warning and precise timing coordination, which is essential for implementing fail-safe recovery in safety-critical systems using the MAX820MCSE+.

Can MAX820MCSE+ protect CMOS RAM during power-down, and how is this implemented?

Yes, the MAX820MCSE+ protects CMOS RAM via its integrated chip-enable (CE) gating function. When reset is asserted, the CE transmission gate disables - blocking CE signals from reaching memory. If CE IN is low at reset assertion, CE OUT remains low for 15µs to complete the current write cycle. This behavior, with 10ns max propagation delay, is explicitly verified in the "Chip-Enable Signal Gating" section of the MAX792/MAX820 datasheet and ensures data integrity during brownout.

What is the purpose of the OVI/OVO pins on MAX820MCSE+, and are they required for basic operation?

The OVI (overvoltage input) and OVO (overvoltage output) pins form an uncommitted comparator with a 1.30V internal reference - fully independent of reset, watchdog, or low-line functions. OVI/OVO requires no connection for basic supervision; it is optional and used only when overvoltage detection is needed (e.g., for load-dump protection). When unused, OVI must be tied to GND or VCC per datasheet guidance - confirming its decoupled, auxiliary role in the MAX820MCSE+ architecture.