Analog Devices Inc./Maxim Integrated MAX813LESA+

Overview

MAX813LESA+ 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 watchdog timeout of 1.6s - used for reliable power-up sequencing and brownout recovery in industrial controllers.

For engineers reviewing the MAX813LESA+ datasheet, MAX813LESA+ pinout, MAX813LESA+ application, or MAX813LESA+ equivalent, key selection criteria include guaranteed RESET validity down to VCC = 1.2V, ±2% reset threshold accuracy, TTL/CMOS-compatible MR input with 150ns minimum pulse width, and lead-free RoHS-compliant 8-SO packaging suitable for extended-temperature embedded systems.

Technical Context

The MAX813LESA+ integrates four core supervisory functions: a precision voltage monitor triggering active-high RESET at 4.65V (±2%), a 1.6s watchdog timer with WDI edge-sensitive clearing, a 1.25V power-fail comparator driving open-drain PFO, and a debounced active-low manual-reset input with internal 250µA pull-up. All functions operate across –40°C to +85°C.

Its RESET output remains valid down to VCC = 1.2V (ISINK = 100µA), enabling robust reset assertion during deep brownout. The PFI-to-PFO propagation delay is under 400ns, and MR-to-RESET assertion delay is 250ns - ensuring fast system-level fault response without external timing components.

Key Specifications

Pinout & Package

MAX813LESA+ is housed in an 8-pin SO (Small Outline) package, RoHS-compliant and marked with '+' suffix per Maxim ordering convention. Pin 1 is located at the top-left corner with notch or dot marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX706ESA+, MAX813LESA+ provides active-high reset essential for Intel 80C51-family µPs and tighter 4.65V threshold accuracy; versus TPS3808G125DBVR, it delivers full supervisory integration - including watchdog, PFI/PFO, and manual reset - in a pin-compatible 8-SO footprint.

Availability

MAX813LESA+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic equipment, automotive infotainment head units, and smart energy meters requiring stable component supply across extended temperature ranges.

Supply support for MAX813LESA+ 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 demanding industrial, medical, and automotive applications.

The MAX813L family delivers integrated microprocessor supervision - combining reset, watchdog, power-fail detection, and manual reset - specifically for reliability-critical embedded systems operating from +5V rails.

FAQ

What is the reset threshold voltage for MAX813LESA+ and how accurate is it?

The MAX813LESA+ has a nominal reset threshold of 4.65V with ±2% tolerance over temperature and supply variations. This specification is guaranteed across the full –40°C to +85°C operating range and ensures consistent reset activation during +5V supply brownout. The device also includes 40mV hysteresis to prevent chatter near the threshold. This accuracy is confirmed in the Electrical Characteristics table of the official Maxim datasheet (Rev. 11, 7/18).

Does MAX813LESA+ provide both active-high and active-low reset outputs?

No, the MAX813LESA+ provides only an active-high RESET output (pin 7). Unlike the MAX707/MAX708 variants, it does not include a complementary active-low RESET output. The MAX813L family replaces the active-low RESET of the MAX705 with an active-high RESET - making it suitable for microprocessors such as the Intel 80C51 that require high-true reset assertion. This is explicitly stated in the General Description and Pin Description sections of the datasheet.

Can MAX813LESA+ monitor voltages other than the main VCC supply?

Yes, MAX813LESA+ can monitor secondary supplies using its PFI (Power-Fail Input) pin, which compares against an internal 1.25V reference. By connecting a resistor divider from the target voltage rail to PFI, designers can configure early-warning detection for +3.3V, +12V, or even negative rails. The datasheet provides example circuits for +12V monitoring (Figure 6) and negative-voltage monitoring (Figure 7), confirming this capability is fully supported and characterized.

What is the minimum VCC voltage at which MAX813LESA+ guarantees valid RESET output?

The MAX813LESA+ guarantees valid RESET output down to VCC = 1.2V, specified at ISINK = 100µA. This is documented in the Electrical Characteristics table under "RESET Output Voltage" for MAX813LE/M grade parts. At this voltage, RESET remains a valid logic high (≥0.9V) when sourcing 4µA, enabling reliable reset assertion during deep undervoltage conditions - a key differentiator versus many competing supervisors.

How does the watchdog timer in MAX813LESA+ get cleared and what is its timeout period?

The MAX813LESA+ watchdog timer clears on any rising or falling edge at the WDI (Watchdog Input) pin, and also clears automatically when RESET is asserted or WDI is three-stated. Its nominal timeout period is 1.6 seconds with ±40% variation over temperature and supply. This value is guaranteed in the Electrical Characteristics table and confirmed in Figure 3 (Watchdog Timing) of the datasheet. Pulses as short as 50ns are reliably detected.