Analog Devices Inc./Maxim Integrated MAX823LEXK+T

Overview

MAX823LEXK+T from Maxim Integrated is a 5-pin microprocessor supervisory circuit with active-low reset, watchdog timer, and manual reset input in SC70-5 package. It monitors +4.63V power supplies, provides 140ms min power-on reset timeout, guarantees RESET validity down to VCC = 1V, and features 1.6s watchdog timeout - used in embedded controllers for reliable brownout and software fault recovery.

For engineers reviewing the MAX823LEXK+T datasheet, MAX823LEXK+T pinout, MAX823LEXK+T application, or MAX823LEXK+T equivalent, key selection criteria include reset threshold accuracy (±1.5% over temperature), ultra-low 6µA operating current (SC70), transient immunity on VCC, and compatibility with bidirectional µP reset pins requiring ≤800µA pullup current.

Technical Context

The MAX823LEXK+T implements a precision bandgap-based reset comparator with 40ppm/°C temperature coefficient and 10mV hysteresis, ensuring stable threshold detection across -40°C to +85°C. Its internal watchdog timer clears on any WDI edge (≥50ns pulse width) and triggers reset if no transition occurs within 1.6s ±25%.

Reset assertion is guaranteed during VCC ramp-up, brownout (VCC < 4.63V), or MR low; RESET remains low for ≥140ms after VCC exceeds threshold or MR returns high. The device drives RESET actively (sourcing/sinking) and supports direct interfacing with bidirectional µP reset pins via controlled pullup current (800µA max).

Key Specifications

Pinout & Package

MAX823LEXK+T is housed in a lead-free SC70-5 surface-mount package (2.0mm × 1.25mm × 0.9mm, 0.65mm pitch), optimized for space-constrained portable and automotive modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX823LEXK+T, MAX823TEUK+T offers different voltage monitoring and wider temperature range but same core functionality; TPS3808G33DBVR reduces power consumption significantly but removes critical safety features - making it unsuitable as a drop-in replacement where watchdog or manual reset is required.

Availability

MAX823LEXK+T is available at Aetrix Electronics and suitable for industrial PLC controllers, medical infusion pumps, and automotive body control modules requiring stable component supply, long-term lifecycle support, and lead-free compliance.

Supply support for MAX823LEXK+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 and mixed-signal ICs for industrial, automotive, and computing applications, with emphasis on reliability and integration.

The MAX823 family delivers compact, single-chip µP supervision for space- and power-constrained systems - targeting embedded controllers and portable equipment where reset accuracy, watchdog coverage, and manual intervention are essential.

FAQ

What is the reset threshold voltage of the MAX823LEXK+T?

The MAX823LEXK+T has a factory-trimmed reset threshold of 4.63V ±1.5% over the full operating temperature range (-40°C to +85°C). This value is specified in the Reset Threshold Table of the datasheet and applies specifically to the "L" suffix variant. The threshold is guaranteed to remain stable with a temperature coefficient of 40ppm/°C, making it suitable for precise +5V rail monitoring in industrial and automotive environments where supply tolerance and thermal drift must be tightly controlled. MAX823LEXK+T uses this fixed threshold without external adjustment.

Does the MAX823LEXK+T include a watchdog timer?

Yes, the MAX823LEXK+T includes a built-in watchdog timer with a nominal timeout period of 1.6 seconds (1.12–2.40s over temperature). The timer is cleared on any rising or falling edge applied to the WDI pin and triggers a reset if no edge occurs within the timeout window. The watchdog function can be disabled by leaving WDI unconnected or driving it with a three-stated output. This capability is intrinsic to the MAX823 series and is fully implemented in MAX823LEXK+T, distinguishing it from MAX824/MAX825 variants that omit either WDI or MR.

What package type and footprint does the MAX823LEXK+T use?

The MAX823LEXK+T is supplied in a lead-free SC70-5 package (2.0mm × 1.25mm × 0.9mm, 0.65mm pitch), as confirmed in the Ordering Information table and Package Outline drawing. This 5-pin surface-mount package is distinct from the SOT23-5 option used by other variants like MAX823_EUK-T. The SC70-5 footprint requires specific land pattern dimensions and reflow profile settings - notably tighter pad spacing and lower thermal mass - and is optimized for high-density portable PCB layouts where board space is constrained.

Can the MAX823LEXK+T drive a bidirectional microprocessor reset pin?

Yes, the MAX823LEXK+T RESET output is designed to interface directly with bidirectional µP reset pins such as those found on the Motorola 68HC11. Its RESET pin sources up to 800µA (for L/M versions) while sinking up to 3.2mA, allowing the µP to override the supervisor's high state by pulling RESET low. This bidirectional compatibility eliminates the need for external level-shifting or open-drain buffering. The MAX823LEXK+T datasheet explicitly confirms this capability in the "Interfacing to µPs with Bidirectional Reset Pins" section and specifies the exact current limits applicable to this variant.

What is the operating current consumption of the MAX823LEXK+T?

The MAX823LEXK+T consumes 6µA typical supply current when operating in the SC70-5 package over the full temperature range (-40°C to +85°C), as documented in the Electrical Characteristics table under "Supply Current (SC70 Only)" for the MAX823L/M group. This ultra-low quiescent current enables multi-year operation in battery-powered applications such as portable medical devices and smart meters. The value is measured with MR and WDI unconnected and reflects actual silicon performance - not a typical-only or room-temperature-only figure - making it a reliable basis for power budgeting in energy-critical designs using MAX823LEXK+T.