Analog Devices Inc./Maxim Integrated MAX813LCSA+

Overview

The MAX813LCSA+ from Maxim Integrated is a low-cost 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 a guaranteed 200ms reset pulse width, and maintains valid RESET down to VCC = 1.1V - enabling reliable reset assertion during brownout and power-up in embedded controllers and industrial instrumentation.

For engineers reviewing the MAX813LCSA+ datasheet, MAX813LCSA+ pinout, MAX813LCSA+ application, or MAX813LCSA+ equivalent, key selection criteria include its 4.65V reset threshold, 1.6s watchdog timeout, 1.25V PFI detection level, active-high RESET output compatibility with Intel 80C51-family µPs, and SO-8 RoHS-compliant packaging for space-constrained PCB layouts.

Technical Context

The MAX813LCSA+ integrates four core supervisory functions on a single die: a precision voltage monitor with 40mV hysteresis, a monostable watchdog timer triggered by WDI edge transitions, a rail-to-rail power-fail comparator with 1.25V internal reference, and a debounced TTL/CMOS-compatible manual-reset input with 250µA internal pull-up.

Its RESET output is actively driven high (not open-drain), remains valid at VCC ≥ 1.1V, and features guaranteed logic levels under sink/source conditions (ISINK = 3.2mA → 0.4V max; ISOURCE = 800µA → VCC − 1.5V min). The watchdog timeout is fixed at 1.6s with 50ns minimum WDI pulse width detection.

Key Specifications

Pinout & Package

MAX813LCSA+ is housed in an 8-pin Small Outline (SO) package, RoHS-compliant and lead-free, with standard 1.27mm pitch and gull-wing leads. Pin 1 is marked with a beveled corner or dot; device orientation follows JEDEC MS-012.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX705CSA+, the MAX813LCSA+ provides active-high RESET compatibility with legacy µPs, while MAX809LCSA+ sacrifices watchdog and PFI functionality for minimal footprint - making MAX813LCSA+ the optimal choice for full-feature, pin-compatible upgrade paths in industrial control designs.

Availability

MAX813LCSA+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic instruments, automotive body control modules, and smart energy meters 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 applications.

The MAX813L belongs to Maxim's µP supervisory product line, designed specifically to replace discrete reset generators and watchdog circuits in resource-constrained embedded systems requiring guaranteed power-on reset, brownout protection, and firmware supervision.

FAQ

What is the reset threshold voltage for MAX813LCSA+ and how tightly is it specified?

The MAX813LCSA+ has a nominal reset threshold of 4.65V with a guaranteed tolerance of ±15mV (4.50V to 4.75V) over temperature and supply variation. This tight specification ensures consistent reset behavior across operating conditions and eliminates ambiguity in system-level brownout response timing - critical for deterministic recovery in safety-critical applications.

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

No, the MAX813LCSA+ provides only an active-high RESET output (pin 7). Unlike the MAX707/MAX708 family, it does not include a complementary active-low RESET signal. Its RESET output is push-pull, not open-drain, and remains valid down to VCC = 1.1V - making it suitable for µPs such as the Intel 80C51 that require active-high reset assertion.

Can MAX813LCSA+ monitor voltages other than the main VCC supply?

Yes, the MAX813LCSA+ can monitor auxiliary supplies using its PFI input. By connecting a resistor divider from the target voltage rail to PFI, the device triggers PFO when the divided voltage falls below its internal 1.25V reference. This enables monitoring of +3.3V, +12V, or even negative rails - with accuracy dependent on resistor tolerance and temperature drift.

What happens to the watchdog timer when the MAX813LCSA+ reset is asserted?

When RESET is asserted - either due to VCC falling below 4.65V or MR being pulled low - the internal watchdog timer is automatically cleared. This prevents unintended watchdog timeout during power-up or manual reset events. The timer resumes counting only after RESET de-asserts and WDI receives a valid edge transition.

Is the MAX813LCSA+ RoHS-compliant and what package type does it use?

Yes, the MAX813LCSA+ is RoHS-compliant and supplied in an 8-pin Small Outline (SO) package with lead-free terminations. The "+" suffix explicitly denotes lead(Pb)-free/RoHS-compliant construction per Maxim's ordering convention. Its JEDEC-standard SO-8 footprint (1.27mm pitch) supports automated assembly and is compatible with industry-standard reflow profiles.