Analog Devices Inc./Maxim Integrated MAX824SEXK+

Overview

MAX824SEXK+ from Maxim Integrated is a 5-pin SC70-packaged microprocessor supervisory circuit with active-low reset, active-high reset, and watchdog timer functions. It monitors +2.93V power supplies, asserts reset for ≥140ms on power-up, guarantees valid reset output down to VCC = 1V, and features 1.6s watchdog timeout. It is used in embedded controllers and critical µP monitoring where dual-reset polarity and transient immunity are required.

For engineers reviewing the MAX824SEXK+ datasheet, MAX824SEXK+ pinout, MAX824SEXK+ application, or MAX824SEXK+ equivalent, key selection criteria include reset threshold accuracy (2.93V ±15mV), watchdog timeout stability over temperature, SC70-5 package compatibility, and dual-reset output capability for interfacing with bidirectional µP reset pins.

Technical Context

The MAX824SEXK+ implements a precision voltage comparator with 40ppm/°C temperature coefficient and hysteresis of 5mV to reject noise-induced false resets. Its watchdog circuit detects WDI edge transitions (≥50ns pulse width) and clears on any rising or falling edge - not level duration - enabling robust software supervision.

It integrates dual complementary reset outputs (RESET and RESET) driven by a single internal reset generator, with independent sourcing/sinking capability: RESET sinks up to 1.2mA at VCC = VRST min, while RESET sources 0.8×VCC under 150µA load. Both outputs remain functional down to VCC = 1V during brownout.

Key Specifications

Pinout & Package

MAX824SEXK+ is housed in a 5-pin SC70-5 package (2.0mm × 2.1mm × 0.9mm, 0.65mm pitch), optimized for space-constrained PCB layouts and reflow-compatible assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX824SEXK+, MAX824TEUK+ offers higher temperature rating but larger SOT23-5 footprint, while TPS3808G33DBVR reduces cost and current draw at the expense of watchdog capability and reset polarity flexibility - making MAX824SEXK+ the optimal balance for compact, dual-polarity, watchdog-enabled designs.

Availability

MAX824SEXK+ is available at Aetrix Electronics and suitable for industrial PLC controllers, portable medical monitors, and smart energy meters requiring stable component supply, long-term lifecycle support, and lead-free compliance.

Supply support for MAX824SEXK+ 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/MAX824/MAX825 family delivers integrated µP supervision - combining reset generation, watchdog timing, and manual reset - specifically for space- and power-constrained embedded systems needing deterministic startup and runtime fault recovery.

FAQ

What is the exact reset threshold voltage of MAX824SEXK+ and how tightly is it specified?

The MAX824SEXK+ has a nominal reset threshold of 2.93V, with a guaranteed tolerance of ±15mV over the full -40°C to +85°C temperature range. This specification is confirmed in the Reset Threshold Table and Electrical Characteristics section of the official datasheet, where VRST is listed as 2.89V (min), 2.93V (typ), and 2.96V (max) at temperature extremes. The 40ppm/°C temperature coefficient ensures minimal drift across operating conditions, making MAX824SEXK+ suitable for precision +3.3V rail monitoring.

Does MAX824SEXK+ provide both active-low and active-high reset outputs simultaneously?

Yes, MAX824SEXK+ provides two independent, complementary reset outputs: pin 1 (RESET) is active-low, and pin 3 (RESET) is active-high. Both outputs are driven by the same internal reset generator and share identical timing - including 140–280ms timeout and 20µs propagation delay - ensuring synchronized assertion and deassertion. This dual-output architecture eliminates the need for external inverters and supports mixed-logic systems, a defining feature of the MAX824 variant within the MAX823/824/825 family.

What is the watchdog timeout behavior of MAX824SEXK+ and how is it triggered?

The MAX824SEXK+ watchdog timer has a nominal timeout of 1.6s, with a guaranteed range of 1.12s to 2.40s over temperature. It is edge-triggered - meaning it resets on *any* rising or falling edge at the WDI pin (pin 4), not on level duration. Pulses as short as 50ns are recognized. If no edge occurs within the timeout window, RESET and RESET are asserted. Leaving WDI unconnected disables the watchdog, as the internal driver services the timer every ~1.4s. This behavior is explicitly documented in the Watchdog Input section and Figure 3 of the MAX824SEXK+ datasheet.

Can MAX824SEXK+ operate reliably down to 1V supply voltage, and what does that mean for system design?

Yes, MAX824SEXK+ guarantees valid reset output states (both RESET and RESET) down to VCC = 1V, as stated in the General Description and Electrical Characteristics tables. This means the device continues to assert or deassert reset correctly even during severe brownout conditions - far below typical µP operating voltage - ensuring the host processor remains held in reset until supply recovery is complete. For system design, this eliminates uncertainty in low-voltage failure modes and removes the need for additional undervoltage lockout (UVLO) circuitry external to MAX824SEXK+.

What package type and footprint does MAX824SEXK+ use, and are there thermal or layout considerations?

MAX824SEXK+ uses the SC70-5 package (2.0mm × 2.1mm × 0.9mm, 0.65mm pitch), as confirmed in the Ordering Information table and Package Information section. Layout best practices include placing a 0.1µF ceramic bypass capacitor directly between VCC (pin 5) and GND (pin 2), with minimal trace length, to ensure transient immunity and stable operation. The SC70's small size demands precise stencil design and reflow profiling; thermal dissipation is limited to 247mW at +70°C (derating 3.1mW/°C above), which is ample given its <6µA supply current.