Analog Devices Inc./Maxim Integrated MAX708RESA

Overview

MAX708RESA from Maxim Integrated is a +3V microprocessor supervisory circuit with dual active-high and active-low reset outputs, 2.93V reset threshold, 200ms reset pulse width, and 1.25V power-fail comparator input-designed for reliable power monitoring in battery-powered portable instruments and industrial controllers operating across -40°C to +85°C.

For engineers reviewing the MAX708RESA datasheet, MAX708RESA pinout, MAX708RESA application, or MAX708RESA equivalent, this device delivers verified dual-reset signaling, brownout immunity down to VCC = 1V, guaranteed reset assertion during power-up/power-down, and integrated manual reset debouncing-critical for embedded systems requiring deterministic startup and fail-safe shutdown behavior.

Technical Context

The MAX708RESA implements a precision voltage-monitoring architecture with independent reset generator and power-fail comparator circuits. Its dual RESET/RESET outputs are asserted simultaneously when VCC falls below 2.93V (±1.5%) or MR is pulled low, and remain asserted for ≥200ms after recovery.

Unlike the MAX706 series, the MAX708RESA omits the watchdog timer but adds complementary reset outputs-enabling direct interface to µPs requiring either active-high or active-low reset logic without external inverters. The PFI input references an internal 1.25V bandgap, supporting configurable power-fail or low-battery detection via external resistor dividers.

Key Specifications

Pinout & Package

MAX708RESA is housed in an 8-pin SOIC (Small Outline Integrated Circuit) package, designated S8-2 per Maxim's packaging nomenclature. This RoHS-compliant, lead-free package measures 4.9mm × 3.9mm × 1.75mm with 1.27mm pitch and gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX708RESA, MAX706RESA adds watchdog capability but sacrifices dual-reset flexibility, while TPS3808G33DBVR achieves nanowatt standby at the cost of losing both PFI monitoring and complementary reset outputs-making MAX708RESA uniquely suited for systems requiring coordinated reset signaling and auxiliary supply supervision.

Availability

MAX708RESA is available at Aetrix Electronics and suitable for industrial PLC modules, portable medical instrumentation, battery-powered data loggers, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX708RESA 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 MAX708 family was designed specifically for robust, low-cost microprocessor supervision in space-constrained, battery-sensitive systems-emphasizing guaranteed reset timing, dual-output flexibility, and precision voltage monitoring without external components.

FAQ

What is the reset threshold voltage for MAX708RESA?

The MAX708RESA has a nominal reset threshold voltage of 2.93V, with a tolerance of ±1.5% over temperature and supply variations. This value is factory-trimmed and applies to the falling edge of VCC; hysteresis is 20mV. The threshold is optimized for +3.3V microprocessor systems and ensures reliable reset assertion before logic instability occurs. MAX708RESA maintains this specification across its full -40°C to +85°C operating range.

Does MAX708RESA include a watchdog timer function?

No, MAX708RESA does not include a watchdog timer. It is functionally distinct from the MAX706 series in this regard. Instead, MAX708RESA provides both active-high (RESET) and active-low (RESET) reset outputs-eliminating the need for external inverters in systems requiring dual-signaling. The absence of watchdog circuitry simplifies design where software-level supervision suffices and reduces quiescent current compared to watchdog-enabled variants like MAX706RESA.

How does the PFI input work on MAX708RESA?

The PFI (Power-Fail Input) on MAX708RESA connects to an internal 1.25V precision bandgap reference comparator. When the voltage at PFI falls below 1.25V, the PFO output goes low to signal impending power failure. Designers configure PFI using an external resistive divider across an unregulated supply (e.g., raw battery or DC-DC input), setting trip points such as 11V on a +12V rail. PFI draws less than 25nA, minimizing loading effects on the divider network.

What is the purpose of the N.C. pin on MAX708RESA?

Pin 8 of MAX708RESA is designated N.C. (No Connection) and is not internally bonded. It must be left electrically floating in the PCB layout. While some designs tie N.C. pins to ground for mechanical stability or EMI reduction, Maxim's datasheet specifies no internal connection-so grounding is optional and carries no functional benefit. Leaving it unconnected avoids unintended current paths and aligns with recommended assembly practices for this device.

Can MAX708RESA operate with a 1.8V supply?

Yes, MAX708RESA is specified to operate down to VCC = 1.2V, so it functions reliably at 1.8V. However, key parameters shift: the reset threshold remains 2.93V, meaning reset will assert whenever VCC falls below that level-so at 1.8V supply, the device remains continuously in reset. MAX708RESA is intended for monitoring 3V-class supplies; its 1.2V minimum rating ensures correct reset behavior during brownout, not normal operation at sub-3V rails.