Analog Devices Inc./Maxim Integrated MAX813LCSA

Overview

MAX813LCSA from Maxim Integrated is a microprocessor supervisory circuit providing active-high reset output, watchdog timer, power-fail comparator, and manual-reset input in an 8-pin SO package. It asserts RESET when VCC drops below 4.65V, delivers 200ms reset pulse width, monitors PFI at 1.25V threshold, and features 1.6s watchdog timeout. It is used in embedded controllers requiring reliable power-up sequencing and brownout protection.

For engineers reviewing the MAX813LCSA datasheet, MAX813LCSA pinout, MAX813LCSA application, or MAX813LCSA equivalent, key selection criteria include guaranteed RESET validity down to VCC = 1.1V, TTL/CMOS-compatible MR input with 250µA internal pull-up, PFO open-drain output for power-fail warning, and SO-8 RoHS-compliant packaging suitable for industrial control and instrumentation designs.

Technical Context

The MAX813L integrates four independent supervisory functions: a precision 4.65V supply monitor with 40mV hysteresis, a 1.6s watchdog timer that clears on WDI edge transitions or RESET assertion, a 1.25V reference-based power-fail comparator driving open-drain PFO, and a debounced active-low manual-reset input with internal 250µA pull-up current.

Its RESET output is active-high and guaranteed functional at VCC ≥ 1.1V, while WDO provides a separate watchdog status signal that goes low on timeout or during VCC brownout-without minimum pulse width guarantee. The device operates across 1.1V to 5.5V supply range and draws only 150–350µA typical quiescent current.

Key Specifications

Pinout & Package

MAX813LCSA is housed in an 8-pin Small Outline (SO) package, RoHS-compliant, with standard 1.27mm pitch and JEDEC MS-012AC outline.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX705CSA and MAX809LCSA, the MAX813LCSA uniquely combines active-high RESET, integrated watchdog timer, and dual-purpose PFI/PFO comparator in one SO-8 device-making it the only direct fit for µP systems requiring coordinated reset, supervision, and early power-fail response without adding discrete comparators or timers.

Availability

MAX813LCSA 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 and long production lifecycles.

Supply support for MAX813LCSA 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and computing markets.

The MAX705–MAX708/MAX813L family was designed to consolidate power-supply monitoring, reset generation, watchdog supervision, and power-fail warning into a single low-cost, low-power IC for microprocessor-based systems.

FAQ

What is the reset threshold voltage for MAX813LCSA?

The MAX813LCSA has a nominal reset threshold of 4.65V with ±1.5% tolerance over temperature. This means the device asserts its active-high RESET output when VCC drops below approximately 4.58V and releases it after VCC rises above ~4.72V, providing hysteresis to prevent oscillation near the trip point. This threshold is factory-trimmed and applies specifically to the MAX813LCSA variant.

Does MAX813LCSA provide both active-high and active-low reset outputs?

No, the MAX813LCSA provides only an active-high RESET output. Unlike the MAX707/MAX708, it does not include a complementary active-low RESET pin. Its pinout includes RESET (pin 7, active-high), WDO (pin 6, watchdog output), and no dedicated active-low reset signal. The MAX813LCSA is functionally equivalent to the MAX705 with RESET substituted for RESET.

How does the watchdog timer in MAX813LCSA operate?

The MAX813LCSA watchdog timer times out after 1.6 seconds if the WDI input (pin 8) remains static-neither rising nor falling. A transition on WDI resets the timer. The timeout causes WDO (pin 6) to go low. WDO also goes low during VCC brownout, but unlike RESET, it has no guaranteed minimum pulse width. The MAX813LCSA watchdog is fully functional and matches the behavior documented for MAX705/MAX706.

Can MAX813LCSA monitor voltages other than +5V?

Yes, the MAX813LCSA can monitor any voltage using its PFI input (pin 4) and internal 1.25V comparator. By connecting a resistor divider from the target voltage to PFI, designers can scale higher rails (e.g., +12V or +3.3V) or monitor negative supplies. The PFO output (pin 5) then signals when the scaled voltage falls below 1.25V. This capability is explicitly confirmed in the MAX813L datasheet's Applications Information section.

What is the minimum supply voltage at which MAX813LCSA guarantees RESET functionality?

The MAX813LCSA guarantees valid RESET output down to VCC = 1.1V, as specified in the Electrical Characteristics table under "RESET Output Voltage" test conditions for MAX813LC. At this voltage, with ISOURCE = 4µA, RESET remains within valid logic-high limits (≤0.8V). This feature ensures reliable reset assertion during deep brownout conditions where other supervisory ICs may fail.