Analog Devices Inc./Maxim Integrated MAX690EPA

Overview

MAX690EPA from Maxim Integrated is an 8-pin microprocessor supervisory circuit providing reset generation, battery backup switchover, watchdog timer, and power-fail warning for +5V systems. It features a 4.65V reset threshold, 50ms reset timeout, fixed 1.6s watchdog timeout, and 1.3V PFI comparator-enabling reliable power monitoring in embedded controllers and intelligent instruments.

For engineers reviewing the MAX690EPA datasheet, MAX690EPA pinout, MAX690EPA application, or MAX690EPA equivalent, key selection considerations include its fixed timing parameters, absence of CE gating or BATT ON output, compatibility with 5V ±5% supplies, and suitability for cost-sensitive, space-constrained µP systems requiring basic supervision without programmability.

Technical Context

The MAX690EPA integrates four core supervision functions in a single 8-pin DIP package: (1) active-low RESET output triggered by VCC falling below 4.65V (±150mV hysteresis), held low for 50ms after recovery; (2) automatic battery switchover between VCC and VBATT (2.0–4.25V range) to VOUT with 70mV/50mV rise/fall thresholds; (3) watchdog timer with fixed 1.6s timeout that asserts RESET if WDI remains static; and (4) 1.3V PFI comparator driving open-drain PFO for early power-fail or low-battery warning.

No CE gating, adjustable timing, or WDO output is implemented-distinguishing it from 16-pin MAX691/693/695 variants. Its internal oscillator is fixed-frequency only; OSC SEL and OSC IN pins are unused. All logic-level inputs (WDI, PFI) are referenced to GND, and VOUT delivers up to 50mA with <0.5V dropout under load.

Key Specifications

Pinout & Package

MAX690EPA is supplied in an 8-pin plastic DIP (Dual In-line Package) with 0.3-inch body width and through-hole mounting. Pin 1 is marked with a notch or dot; pin numbering follows standard counter-clockwise layout from top view.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX692EPA, MAX690EPA offers higher reset threshold margin for stable 5V rails; compared with TPS3823-50DBVR, MAX690EPA provides full supervision (battery switchover, watchdog, PFI) at the cost of larger footprint and higher pin count-making it optimal for µP systems needing integrated reliability without programmability.

Availability

MAX690EPA is available at Aetrix Electronics and suitable for industrial controllers, automotive body electronics, and medical diagnostic instruments requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for MAX690EPA 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, automotive, and computing applications.

The MAX690 family was designed specifically for cost-effective, space-efficient microprocessor supervision in embedded systems-delivering precision reset, battery backup, and watchdog functions without external timing components.

FAQ

What is the operating temperature range for MAX690EPA?

The MAX690EPA is rated for operation from -40°C to +85°C (E-suffix grade). This extended industrial temperature range ensures reliable performance in automotive cabin modules, factory-floor controllers, and outdoor instrumentation where ambient temperatures exceed commercial limits. The MAX690EPA's electrical specifications-including reset threshold, watchdog timeout, and VOUT regulation-are guaranteed across this full range.

Does MAX690EPA support adjustable reset or watchdog timing?

No, MAX690EPA does not support adjustable timing. Its reset timeout is fixed at 50ms and watchdog timeout at 1.6s nominal-both implemented via internal oscillator and logic. Unlike the 16-pin MAX691/MAX695, the MAX690EPA lacks OSC SEL and OSC IN pins for external timing control. This simplifies design but limits flexibility for systems requiring custom timeout periods.

Can MAX690EPA drive CMOS RAM directly from VOUT?

Yes, MAX690EPA can drive CMOS RAM directly from VOUT. Its VOUT pin delivers up to 50mA with <0.5V dropout at full load and includes short-circuit protection. A 0.1µF bypass capacitor is mandatory at VOUT for stability. For RAM loads exceeding 50mA or requiring lower dropout, an external PNP transistor driven by the BATT ON signal (not available on MAX690EPA) would be needed-so alternative parts like MAX691 should be considered.

How does MAX690EPA handle power-fail detection without a dedicated PFO pull-up?

MAX690EPA's PFO is an open-drain output requiring an external pull-up resistor (typically 10kΩ to VCC or VOUT). When PFI falls below 1.3V, PFO pulls low to signal power fail or low battery. The internal comparator is disabled and PFO forced low when VCC < VBATT-preventing false warnings during battery backup. No internal pull-up exists; omission of the external resistor leaves PFO floating and nonfunctional.

Is MAX690EPA pin-compatible with other MAX690 family members?

MAX690EPA shares identical pinout and function mapping with MAX692EPA and MAX694EPA-same 8-pin DIP layout, VBATT/RESET/WDI/PFO/VOUT/VCC/PFI/GND assignments, and compatible PCB footprint. However, it is not pin-compatible with 16-pin variants (MAX691/MAX693/MAX695) due to differing pin count, additional signals (CE IN/OUT, BATT ON, WDO), and distinct package dimensions.