Analog Devices Inc./Maxim Integrated MAX692AEPA

Overview

MAX692AEPA from Maxim Integrated is a microprocessor supervisory circuit providing reset generation, battery-backup switching, watchdog timer, and power-fail detection in a single 8-pin DIP package. It asserts an active-low RESET pulse during power-up (VCC ≥ 1V), brownout (VCC < 4.40V), and watchdog timeout (1.6s), while delivering VOUT from VCC or VBATT with 40mV switchover hysteresis-enabling reliable operation in industrial controllers and battery-backed instrumentation.

For engineers reviewing the MAX692AEPA datasheet, MAX692AEPA pinout, MAX692AEPA application, or MAX692AEPA equivalent, key selection criteria include its −40°C to +85°C operating range, guaranteed RESET assertion down to VCC = 1.2V, 200μA quiescent supply current, and compatibility with lithium backup batteries up to 4.55V.

Technical Context

The MAX692AEPA integrates four independent functional blocks: a precision reset generator with 4.40V threshold and 200ms pulse width, a 1.6s watchdog timer cleared by WDI edge transitions, a 1.25V reference-based power-fail comparator (PFI/PFO), and a dual-path battery switchover circuit with 5Ω (VCC→VOUT) and 80Ω (VBATT→VOUT) PMOS switches.

Its reset logic guarantees low-state output from VCC = 1.2V upward, with hysteresis preventing chatter during slow VCC ramps; the PFI input draws only 25nA max, enabling high-impedance voltage-divider monitoring of unregulated supplies, while the WDI pin features internal 35% VCC bias and 50kΩ impedance for floating-state watchdog disable.

Key Specifications

Pinout & Package

MAX692AEPA is housed in an 8-pin plastic DIP (PDIP) package with 0.300" wide body and 0.100" lead pitch, compliant with JEDEC MS-001. Pin 1 is marked with a notch or dot; leads are tin-lead or RoHS-compliant (add '+' suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX692AEPA, MAX802MEPA offers verified ±2% PFI accuracy for precision supply monitoring, while MAX692AESA provides identical electrical behavior in a surface-mount package-enabling trade-offs between manufacturability, thermal management, and measurement confidence without redesigning reset logic.

Availability

MAX692AEPA is available at Aetrix Electronics and suitable for industrial controllers, battery-powered instrumentation, critical μP power monitoring, and intelligent edge sensors requiring stable component supply across extended temperature ranges.

Supply support for MAX692AEPA 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 communications applications, with expertise in power management and reliability-critical subsystems.

The MAX692A family targets microprocessor supervisory functions-integrating reset, watchdog, battery switchover, and power-fail detection to replace discrete solutions in systems where uptime and data integrity are essential.

FAQ

What is the guaranteed minimum VCC level at which MAX692AEPA asserts RESET?

The MAX692AEPA guarantees RESET assertion down to VCC = 1.2V across its full operating temperature range (−40°C to +85°C). This ensures reliable reset initiation even during severe undervoltage transients, unlike some supervisory ICs that require VCC ≥ 2.0V. The specification is explicitly confirmed in the Electrical Characteristics table under "RESET Output Voltage" conditions for MAX69_AE/M grade parts.

Does MAX692AEPA support active-high reset outputs?

No, MAX692AEPA provides only an active-low RESET output. The active-high variant is the MAX805L series (e.g., MAX805LEPA), which substitutes RESET for RESET. MAX692AEPA's pin 7 is strictly RESET; attempting to use it as an active-high signal violates its specified logic polarity and may cause system malfunction. Always verify reset polarity compatibility with the target microprocessor's requirements.

Can MAX692AEPA monitor negative supply rails?

Yes, MAX692AEPA can monitor negative voltages using an external resistor network connected to the PFI pin, as shown in Figure 7 of the datasheet. The PFI input compares against an internal 1.25V reference, so a properly scaled voltage divider allows detection of negative rail degradation (e.g., −5V dropping toward 0V). Accuracy depends on resistor tolerance and PFI input current (≤25nA), not on VCC polarity.

What is the maximum allowable backup battery voltage for MAX692AEPA?

The maximum allowable backup battery voltage for MAX692AEPA is 4.55V, as specified in Table 2 ("Allowable Backup-Battery Voltages") for MAX692A/MAX802M variants. Exceeding this risks excessive current flow through the internal substrate diode (D1 in Figure 3) when VCC approaches the reset threshold, potentially damaging the device or causing premature battery discharge.

How does the watchdog timer in MAX692AEPA behave when WDI is left unconnected?

When WDI is left floating, the MAX692AEPA watchdog timer is disabled due to internal 35% VCC bias and high input impedance (50kΩ), placing WDI in a non-logic state. This prevents unintended resets-a key design feature for systems where watchdog functionality is optional. The timer only activates when WDI is actively driven high or low for >1.6s, or when clean edges are applied to clear and restart timing.