Analog Devices Inc./Maxim Integrated MAX820LCSE+T

Overview

MAX820LCSE+T 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 industrial systems requiring reliable power-on reset and brownout protection.

For engineers reviewing the MAX820LCSE+T datasheet, MAX820LCSE+T pinout, MAX820LCSE+T application, or MAX820LCSE+T equivalent, this page delivers verified functional identity, exact pin roles, confirmed reset threshold (4.62V), watchdog timing behavior, CE propagation delay (10ns max), and real-world substitution guidance for critical µP monitoring designs.

Technical Context

The MAX820LCSE+T implements dual-comparator supervision: one for reset assertion at VCC ≤ 4.62V (±2%), another for low-line warning at 4.74V (120mV above reset threshold), both with hysteresis. Its watchdog function monitors WDI transitions and asserts WDPO (pulse) then WDO (latched) after timeout - configurable via SWT capacitor or fixed 1.6s mode.

It integrates a bidirectional chip-enable transmission gate (CE IN → CE OUT) with 10ns max propagation delay and automatic disable during reset to prevent memory corruption. The RESET output remains valid down to VCC = 1V, and MR accepts TTL/CMOS logic or pushbutton inputs with 12µs propagation delay and 25µs minimum pulse width.

Key Specifications

Pinout & Package

MAX820LCSE+T is housed in a 16-pin narrow SOIC (SO) package, 3.9mm width, RoHS-compliant lead-free construction (+T suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX820LCSE+T, MAX823TESA+ reduces footprint but sacrifices low-line warning and watchdog pulse functionality, while TPS3808G33DBVR offers lower cost in 3.3V systems but cannot replace the dual-threshold, memory-gating, and fault-logging capabilities essential for complex µP supervision.

Availability

MAX820LCSE+T is available at Aetrix Electronics and suitable for industrial automation, medical diagnostics, telecom infrastructure, and automotive body electronics requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX820LCSE+T 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, mixed-signal, and power management ICs for demanding industrial, medical, and communications applications.

The MAX820L series was developed specifically for high-reliability microprocessor supervision - delivering accurate reset thresholds, robust watchdog behavior, and integrated memory protection in compact SOIC packages.

FAQ

What is the exact reset threshold voltage for MAX820LCSE+T?

The MAX820LCSE+T has a nominal reset threshold voltage of 4.62V with ±2% accuracy over temperature and supply variation. This value is factory-trimmed and guaranteed per the datasheet's Electrical Characteristics table for the 'L' suffix variant. The threshold remains stable across the full operating range of -40°C to +85°C, making it suitable for industrial environments where voltage tolerance is critical. MAX820LCSE+T uses internal threshold mode unless RESET IN/INT is pulled above 600mV.

Does MAX820LCSE+T support external reset threshold programming?

Yes, MAX820LCSE+T supports external programming mode via the RESET IN/INT pin. When this pin is biased above 600mV (e.g., using a resistor divider from VCC), the device disconnects from its internal 1.30V reference and allows user-defined reset and low-line thresholds using external resistors connected to LLIN/REFOUT and RESET IN/INT. The MAX820LCSE+T retains its ±2% accuracy advantage over the MAX792 in this mode when external components are selected appropriately.

How does the watchdog function behave in MAX820LCSE+T?

The MAX820LCSE+T watchdog monitors the WDI pin for transitions. If no edge occurs within the timeout period (1.6s nominal with SWT = VCC), WDPO pulses low for 500µs–6ms, followed 70ns later by WDO going low and staying latched until the next WDI transition. This two-stage alert enables single-fault warning (WDPO) and hardware shutdown (WDO), and supports two-consecutive-fault latching when combined with an external D flip-flop - a key safety feature implemented directly by MAX820LCSE+T.

What is the purpose of the CE IN and CE OUT pins on MAX820LCSE+T?

The CE IN and CE OUT pins implement a transmission gate that passes chip-enable signals during normal operation but disables automatically during reset assertion. This prevents partial memory writes during power collapse - especially critical for CMOS RAM and EEPROM. With a guaranteed 10ns max propagation delay, MAX820LCSE+T ensures compatibility with fast µPs, and its CE gating eliminates the need for external logic or software workarounds to ensure memory integrity during brownout.

Can MAX820LCSE+T operate down to 1V supply voltage?

Yes, the RESET output of MAX820LCSE+T is guaranteed functional down to VCC = 1V, maintaining valid logic levels for µP reset assertion even during deep brownout. While internal comparators and watchdog require ≥2.75V to operate, the reset path remains active and predictable below that level - a key differentiator for fail-safe systems. An external 10kΩ pull-down on RESET ensures validity down to GND, as documented in Figure 5 of the MAX820 datasheet.