Analog Devices Inc./Maxim Integrated MAX699EPA

Overview

MAX699EPA from Maxim Integrated is an industrial-grade voltage supervisor and watchdog timer IC that monitors +5V supplies in microprocessor systems, asserts a minimum 140ms active-low RESET pulse during power-up, brownout (4.4V threshold), and power-down, and provides watchdog timeout detection at 1s with WDI input monitoring. It operates from -40°C to +85°C in 8-lead PDIP packaging and requires zero external components.

For engineers reviewing the MAX699EPA datasheet, MAX699EPA pinout, MAX699EPA application, or MAX699EPA equivalent, key selection criteria include its guaranteed 4.65V reset threshold hysteresis (40mV), open-drain RESET output capable of sinking 1.6mA at 0.4V, watchdog disable-by-open-WDI feature, and compatibility with legacy 8-pin μP reset circuits requiring industrial temperature range support.

Technical Context

The MAX699EPA integrates a precision bandgap-based voltage comparator with internal hysteresis and a monostable reset timer, ensuring reliable power-on sequencing without external RC timing. Its watchdog circuit uses a digital timeout counter triggered by WDI transitions, with automatic disable when WDI is left floating.

Unlike the SO-package variants, the MAX699EPA (8-pin PDIP) provides only the inverted RESET output - no non-inverted RESET or WDO outputs - and maps WDI to Pin 6, consistent with its pin-compatible MAX698EPA base design but adding watchdog functionality.

Key Specifications

Pinout & Package

MAX699EPA is housed in an 8-lead plastic dual-inline package (PDIP) with 0.3-inch width, standard through-hole mounting, and RoHS-compliant lead-free option (MAX699EPA+).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage supervision and watchdog applications.

Compared with MAX699EPA, MAX698EPA removes watchdog enforcement while retaining identical reset behavior and industrial rating, whereas TPS3823-46DBVR trades integration and watchdog capability for size and standby efficiency - making MAX699EPA the sole choice when both precise reset timing and hardware-level firmware supervision are required in PDIP form factor.

Availability

MAX699EPA is available at Aetrix Electronics and suitable for computers, controllers, intelligent instruments, and critical μP power monitoring applications requiring stable component supply across extended temperature ranges and long-term industrial program support.

Supply support for MAX699EPA 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, mixed-signal, and power management ICs for industrial, computing, and communications systems.

The MAX698/MAX699 product line delivers cost-optimized, zero-component reset and watchdog solutions targeting microprocessor-based systems needing guaranteed power-up sequencing and firmware health monitoring.

FAQ

What is the reset threshold voltage of the MAX699EPA?

The MAX699EPA has a typical reset threshold of 4.65V, with a guaranteed minimum of 4.50V and maximum of 4.75V across its full -40°C to +85°C operating range. This threshold is internally generated using a precision bandgap reference, and hysteresis of 40mV ensures stable release above the trip point, eliminating chatter during slow VCC ramps.

Does the MAX699EPA require external components to operate?

No, the MAX699EPA requires zero external components. Its internal voltage reference, timing circuitry, and open-drain RESET driver are fully self-contained. Only a pull-up resistor on the RESET pin is needed for proper logic-level interfacing - no capacitors, resistors, or trimming networks are required for basic reset or watchdog operation.

How is the watchdog function disabled on the MAX699EPA?

The watchdog function on the MAX699EPA is disabled by leaving the WDI pin (Pin 6) unconnected. The datasheet explicitly states that an open WDI input disables the watchdog timer, allowing the device to operate as a pure reset supervisor identical to the MAX698EPA. No pull-up or pull-down is required.

What is the function of Pin 7 on the MAX699EPA?

Pin 7 on the MAX699EPA is marked N.C. (No Connection) and has no internal connection. It must remain unconnected in the PCB layout - it is not a spare I/O, test pad, or configurable terminal. Connecting it may cause undefined behavior or damage per the Absolute Maximum Ratings table.

Can the MAX699EPA drive a microprocessor's RESET pin directly?

Yes, the MAX699EPA's open-drain RESET output can directly drive most μP RESET inputs when used with an appropriate external pull-up resistor (typically 10kΩ to VCC). It sinks ≥1.6mA at ≤0.4V, satisfying common μP reset low-voltage requirements, and its 140ms minimum pulse width exceeds typical processor reset hold-time specifications.