Analog Devices Inc./Maxim Integrated MAX820SCPE+

Overview

MAX820SCPE+ from Maxim Integrated is a microprocessor supervisory circuit providing reset generation, manual reset input, two-stage power-fail warning (low-line comparator 120mV above reset threshold), watchdog timer with pulsed fault output (WDPO), and chip-enable gating for nonvolatile memory protection. It guarantees ±2% reset and low-line threshold accuracy in external programming mode and operates down to VCC = 1V for guaranteed RESET validity. Used in embedded controllers and critical µP power monitoring systems.

For engineers reviewing the MAX820SCPE+ datasheet, MAX820SCPE+ pinout, MAX820SCPE+ application, or MAX820SCPE+ equivalent, this page delivers verified functional identity, confirmed ±2% threshold accuracy, validated 16-pin PDIP package mapping, full 16-pin terminal roles, and two manufacturer-confirmed alternative parts with documented technical and application differences.

Technical Context

The MAX820SCPE+ integrates independent reset and low-line comparators with factory-trimmed ±2% accuracy, a programmable watchdog timer (1.6s nominal timeout via SWT pin), and a bidirectional chip-enable transmission gate with ≤10ns propagation delay. Its RESET IN/INT pin selects between internal fixed thresholds (via GND tie) or external resistor-programmed thresholds (via ≥600mV bias).

It features dual reset outputs (active-low RESET and active-high RESET), overvoltage detection (OVI/OVO), and memory write-cycle completion support via CE IN/CE OUT gating. The device disables CE path during reset assertion and maintains CE OUT low for 15µs after reset if CE IN was low-ensuring RAM write integrity during brownout.

Key Specifications

Pinout & Package

MAX820SCPE+ is housed in a 16-pin plastic DIP (dual in-line package) with 0.3-inch body width and through-hole mounting. Pin spacing is 0.1 inch, compatible with standard PCB layouts and socketing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX792SCPE+, the MAX820SCPE+ delivers tighter ±2% threshold accuracy for robust brownout response; compared with TPS3823MPDBVR, it adds critical safety features including pulsed watchdog output, chip-enable gating, and dual reset outputs-enabling fail-safe memory management and hardware-level fault escalation.

Availability

MAX820SCPE+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic instruments, telecom remote terminal units, and automotive body control modules requiring stable component supply across extended temperature ranges (0°C to +70°C).

Supply support for MAX820SCPE+ 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 in industrial, medical, and communications systems.

The MAX820SCPE+ belongs to Maxim's microprocessor supervisory product line, engineered specifically for fail-safe µP power monitoring, memory write protection, and deterministic watchdog escalation in mission-critical embedded systems.

FAQ

What is the key functional difference between MAX820SCPE+ and MAX792SCPE+?

The MAX820SCPE+ guarantees ±2% accuracy for both reset and low-line thresholds in external programming mode, whereas the MAX792SCPE+ specifies ±3%. This tighter tolerance enables more precise brownout detection and earlier NMI warning in systems with tight supply margins. All other pinout, timing, and feature sets-including WDPO, CE gating, and 200ms reset delay-are identical between MAX820SCPE+ and MAX792SCPE+.

Does MAX820SCPE+ support watchdog timeout adjustment, and how is it implemented?

Yes, MAX820SCPE+ supports adjustable watchdog timeout via the SWT pin. With SWT tied to VCC, the timeout is 1.6s nominal. To adjust, connect a capacitor from SWT to GND: timeout = k × C (in nF) ms, where k = 16.2 at VCC = 5V and k = 27 at VCC = 3V. Capacitor values must exceed 4.7nF; floating or grounded SWT is prohibited. This configuration is fully supported in the MAX820SCPE+ datasheet and validated across temperature.

How does the chip-enable (CE) gating function protect memory in MAX820SCPE+?

The MAX820SCPE+ uses a series transmission gate between CE IN and CE OUT. During normal operation, CE transitions pass through with ≤10ns delay. When reset is asserted, the gate disables-blocking CE signals to prevent spurious writes. If CE IN is low at reset assertion, CE OUT remains low for 15µs to complete the current memory write cycle. This behavior is explicitly characterized in the MAX820SCPE+ datasheet and ensures CMOS RAM/EEPROM integrity during brownout.

Can MAX820SCPE+ generate a nonmaskable interrupt (NMI), and which pin provides it?

Yes, MAX820SCPE+ generates an NMI via the LOW LINE pin (Pin 10), which asserts low 120mV above the reset threshold in internal threshold mode. This provides early warning before reset activation, allowing the µP to execute critical save routines. In external programming mode, LOW LINE asserts when LLIN/REFOUT falls below 1.30V. The NMI functionality is integral to the MAX820SCPE+ architecture and confirmed in its block diagram and timing specifications.

What is the minimum VCC level at which MAX820SCPE+ guarantees valid RESET output assertion?

The MAX820SCPE+ guarantees valid RESET output assertion down to VCC = 1V, as explicitly stated in the datasheet's General Description and Electrical Characteristics tables. At VCC = 1V, RESET remains functional with defined sink/source capability (e.g., 0.01V–0.3V low-state voltage with 50µA sink). This specification is unique to the MAX820SCPE+ family and enables reliable reset signaling during deep brownout conditions where other supervisors fail.