Analog Devices Inc./Maxim Integrated MAX820LCSE+

Overview

MAX820LCSE+ 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 - used in embedded controllers and critical power-monitoring systems where deterministic brownout recovery and memory write protection are required.

For engineers reviewing the MAX820LCSE+ datasheet, MAX820LCSE+ pinout, MAX820LCSE+ application, or MAX820LCSE+ equivalent, this page delivers verified functional identity, validated 16-pin SOIC-N package mapping, confirmed ±2% threshold accuracy (vs. MAX792's ±3%), exact watchdog timing behavior, and real-world CE gating propagation delay (≤10ns), enabling confident selection for industrial control and instrumentation designs.

Technical Context

The MAX820LCSE+ implements dual-voltage monitoring via independent reset and low-line comparators, both referenced to a precision 1.30V internal bandgap. Its reset comparator guarantees valid output down to VCC = 1V, while the low-line comparator asserts 120mV above the reset threshold with 15mV hysteresis - ensuring early NMI warning before reset activation. The device supports both internal threshold mode (grounded RESET IN/INT) and external programming mode (resistor-divider–based thresholds).

Its watchdog function uses the SWT pin to set timeout via capacitor (k = 16.2 for VCC = 5V), generating WDPO pulse (≥500µs) followed by WDO assertion (70ns later); CE IN-to-CE OUT transmission gate enables memory write-cycle completion during power-down with ≤10ns propagation delay and 15µs hold time when CE IN is low at reset assertion.

Key Specifications

Pinout & Package

MAX820LCSE+ is housed in a 16-pin narrow SOIC (SOIC-N) package, 3.9mm body width, 1.27mm pitch, RoHS-compliant lead-free finish (+ suffix). Pin 1 is marked with dot or bevel; pin numbering follows standard counter-clockwise convention from top-left corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX792LCSE+, the MAX820LCSE+ delivers tighter threshold accuracy and guaranteed sub-1V reset operation - critical for fail-safe systems; versus TPS3808G33DBVR, it offers comprehensive supervision (dual reset, watchdog, CE gating, NMI) at the cost of higher integration complexity and price.

Availability

MAX820LCSE+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic instruments, telecom base station management units, automotive body control modules, and critical µP power monitoring requiring stable component supply across extended temperature ranges (0°C to +70°C).

Supply support for MAX820LCSE+ 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 - serving industrial, medical, and communications markets since 1983.

The MAX820LCSE+ belongs to Maxim's microprocessor supervisory product line, engineered specifically for deterministic power-fail response, memory write protection, and multi-level voltage monitoring in safety-critical embedded systems.

FAQ

What is the guaranteed minimum operating voltage for MAX820LCSE+ reset functionality?

The MAX820LCSE+ guarantees valid RESET output down to VCC = 1V - a key differentiator from the MAX792 series. This is achieved via optimized output stage design and internal biasing. Below 1V, reset assertion remains functional but saturation voltage rises; for operation down to GND, an external 10kΩ pull-down on RESET is recommended. This specification is explicitly tested and guaranteed per the MAX820 datasheet Absolute Maximum Ratings and Electrical Characteristics tables.

How does the MAX820LCSE+ implement low-line warning, and what is its relationship to the reset threshold?

The MAX820LCSE+ asserts the LOW LINE output 120mV above the programmed reset threshold - for example, with a 4.62V reset threshold (L suffix), LOW LINE triggers at 4.74V. This provides deterministic early warning before reset activation, allowing the µP to execute safe-state routines. The 15mV hysteresis prevents chatter near the threshold. This behavior is fixed in internal threshold mode and preserved in external mode when using the same reference node for both comparators.

Can the watchdog timeout period of MAX820LCSE+ be adjusted, and how is it calculated?

Yes, the MAX820LCSE+ watchdog timeout is adjustable via a capacitor from SWT to GND. With VCC = 5V, timeout = 16.2 × C (nF) ms; with VCC = 3V, timeout = 27 × C (nF) ms. For example, a 100nF capacitor yields ~1.62s at 5V. The formula applies for C ≥ 4.7nF. Leaving SWT floating or grounded invalidates operation - it must be pulled to VCC or capacitively coupled to GND. This adjustment is fully supported in the MAX820 datasheet Figure 10 and Electrical Characteristics table.

What is the purpose of the CE IN and CE OUT pins on MAX820LCSE+, and how do they behave during reset?

The CE IN and CE OUT pins form a transmission gate that blocks chip-enable signals during reset to prevent corrupted memory writes. When reset is deasserted, CE IN passes directly to CE OUT with ≤10ns delay. When reset asserts, CE IN goes high-impedance and CE OUT is pulled high - unless CE IN was low at reset assertion, in which case CE OUT stays low for 15µs to complete the current write cycle. This behavior is documented in the MAX820 datasheet Detailed Description section and Figure 9 timing diagram.

Is MAX820LCSE+ pin-compatible with MAX792LCSE+, and what are the key functional differences?

Yes, MAX820LCSE+ is fully pin-compatible and functionally identical to MAX792LCSE+ in layout and interface. The primary differences are tighter ±2% reset/low-line threshold accuracy (vs. ±3% for MAX792) and guaranteed RESET validity down to VCC = 1V (vs. not guaranteed below 2.5V for MAX792). All timing, pin functions, and electrical specs except those two parameters are identical - confirmed in the MAX792/MAX820 datasheet General Description and Electrical Characteristics sections.