Analog Devices Inc./Maxim Integrated MAX697EWE+

Overview

MAX697EWE+ from Maxim Integrated is a microprocessor supervisory circuit designed for power-supply monitoring and CMOS RAM write protection in industrial and embedded systems. It provides adjustable low-line reset (1.25V–1.35V), watchdog timeout (100ms/1.6s), 1.3V power-fail detection, CE IN/CE OUT gating logic, and consumes ≤300µA supply current over –40°C to +85°C.

For engineers reviewing the MAX697EWE+ datasheet, MAX697EWE+ pinout, MAX697EWE+ application, or MAX697EWE+ equivalent, key selection considerations include its lack of battery-backup switching (vs. MAX696), dedicated chip-enable control for nonvolatile memory, low-quiescent-current operation, and wide-temperature SO package compatibility with legacy μP reset architectures.

Technical Context

The MAX697EWE+ integrates six core supervisory functions: precision 1.3V low-line detection with hysteresis, dual-mode watchdog timer (internal oscillator or external clock/capacitor), independent PFI comparator for early power-fail warning, active-high and active-low RESET outputs with 50ms default timeout, and bidirectional CE gating logic that forces CE OUT high during brownout or VCC failure. Its architecture isolates memory write control from supply rail instability without requiring external logic.

All timing functions derive from a 10.24kHz internal oscillator (when OSC SEL is high/floating) or user-configurable external timing (capacitor on OSC IN or clock signal). The CE IN/CE OUT path features 50ns propagation delay and automatic override when LLIN falls below 1.3V - ensuring data integrity during voltage transients without software intervention.

Key Specifications

Pinout & Package

MAX697EWE+ is housed in a 16-pin Wide SO (SOIC-W) package, 7.5mm body width, 1.27mm pitch, RoHS-compliant lead-free construction (indicated by '+' suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX696EWE+, MAX697EWE+ trades battery-switching capability for lower power and integrated CE control - making it optimal for write-protected memory systems without backup power. Versus TPS3808G33DBVR, it delivers comprehensive supervision (watchdog, dual reset, PFI, CE gating) at higher current cost but significantly greater functional coverage.

Availability

MAX697EWE+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic instruments, smart energy meters, and ruggedized data loggers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX697EWE+ 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 communications markets.

The MAX697EWE+ belongs to Maxim's microprocessor supervisory product line, engineered to replace discrete reset generators and watchdog circuits in μP-based systems demanding reliable power monitoring and memory protection under harsh environmental conditions.

FAQ

What is the primary functional distinction between MAX697EWE+ and MAX696EWE+?

The MAX697EWE+ omits battery-backup switching circuitry (no VBATT, VOUT, or BATT ON pins) and instead adds CE IN/CE OUT pins for hardware-enforced RAM/EEPROM write protection. This reduces supply current to ≤300µA versus up to 4mA for MAX696EWE+ in VCC mode, making MAX697EWE+ ideal for write-protected memory systems without backup power requirements.

How does the CE gating function operate in MAX697EWE+ during a brownout event?

In MAX697EWE+, CE OUT is a buffered replica of CE IN when LLIN > 1.3V. If LLIN drops below 1.3V, CE OUT is forced high within 150ns - regardless of CE IN state - blocking writes to attached CMOS RAM or EPROM. This hardware-level override ensures data integrity without firmware involvement, and remains active until LLIN recovers above 1.312V.

Can MAX697EWE+ generate a reset pulse shorter than 50ms?

Yes. While the default reset timeout is 50ms, MAX697EWE+ supports adjustable timing via the OSC IN pin: connecting an external capacitor (e.g., 47pF) yields ~200ms, while using an external clock signal allows precise control down to 512 clock cycles (~50µs at 10MHz). Table 1 in the datasheet specifies exact configurations for reduced pulse widths.

What is the recommended approach to configure early power-fail warning using PFI/PFO on MAX697EWE+?

To configure early power-fail warning, connect PFI to a resistor divider tapping the unregulated DC input of the VCC regulator. Set the divider ratio so PFI falls below 1.3V 5–20ms before LLIN drops - providing time to execute interrupt-driven data save routines. PFO then asserts low to trigger the μP's NMI line, initiating controlled shutdown before RESET activates.

Does MAX697EWE+ require external pull-up resistors on its open-drain outputs?

No. MAX697EWE+'s RESET, LOW LINE, WDO, and PFO outputs include internal 3µA pull-ups, enabling direct connection to CMOS inputs without external components. However, for driving higher-capacitance buses or longer traces, a 10kΩ external pull-up is recommended to ensure clean signal edges and meet timing specifications.