Analog Devices Inc./Maxim Integrated MAX707CPA

Overview

MAX707CPA from Maxim Integrated is a microprocessor supervisory circuit providing active-high reset output, power-fail monitoring, manual-reset input, and watchdog timer disable (replaced by active-high RESET), with 4.65V supply-voltage threshold, 200ms reset pulse width, and guaranteed RESET validity down to VCC = 1V. It monitors +5V µP power rails in embedded controllers and industrial instrumentation.

For engineers reviewing the MAX707CPA datasheet, MAX707CPA pinout, MAX707CPA application, or MAX707CPA equivalent, key selection criteria include reset threshold accuracy (4.65V ±150mV), manual-reset debouncing (140ms min pulse), PFI comparator reference (1.25V), and compatibility with TTL/CMOS logic interfaces under 0°C to +70°C operation.

Technical Context

The MAX707CPA integrates a precision voltage monitor with 4.65V threshold and 40mV hysteresis, a 1.25V reference-based power-fail comparator (PFI/PFO), and an active-high RESET output that complements the active-low RESET signal. Its internal 250µA MR pull-up enables direct pushbutton interfacing without external components.

Unlike the MAX705/MAX706, the MAX707CPA replaces the watchdog output (WDO) with a second reset output (RESET), eliminating watchdog timeout functionality but enabling dual-polarity reset signaling for µPs requiring active-high assertion-such as Intel 80C51-family processors.

Key Specifications

Pinout & Package

MAX707CPA is housed in an 8-pin plastic DIP (dual in-line package) with 0.3-inch body width and standard 0.1-inch pin pitch, suitable for through-hole soldering and socket-based evaluation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX705CPA and MAX813LCPA, the MAX707CPA uniquely delivers simultaneous active-high and active-low reset outputs without watchdog overhead-making it optimal for legacy µP interfaces requiring complementary reset signaling and minimal feature set complexity.

Availability

MAX707CPA is available at Aetrix Electronics and suitable for industrial controllers, embedded test instrumentation, legacy µP system upgrades, and low-power data acquisition nodes requiring stable component supply across extended production lifecycles.

Supply support for MAX707CPA 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, communications, and computing applications.

The MAX707CPA belongs to the MAX705–MAX708/MAX813L family of low-cost µP supervisory circuits engineered specifically for reliable power monitoring and reset generation in cost-sensitive embedded systems.

FAQ

What is the reset threshold voltage of the MAX707CPA?

The MAX707CPA has a nominal reset threshold of 4.65V, with guaranteed limits of 4.50V (min) and 4.75V (max) over temperature and supply variations. This threshold ensures reset assertion before +5V µP supply brownout compromises system stability, and its 40mV hysteresis prevents oscillation near the trip point. The MAX707CPA uses this fixed threshold-unlike adjustable variants-and is specified for 0°C to +70°C operation.

Does the MAX707CPA include a watchdog timer?

No, the MAX707CPA does not include a functional watchdog timer. Unlike the MAX705CPA or MAX813LCPA, the MAX707CPA substitutes the watchdog output (WDO) with an active-high RESET output. Pin 8 (WDO) is internally unconnected (N.C.) on the MAX707CPA, and no watchdog timeout period or WDI input is implemented. This design prioritizes dual-polarity reset signaling over autonomous fault recovery.

Can the MAX707CPA operate with supply voltages below 5V?

Yes, the MAX707CPA operates from 1.0V to 5.5V and guarantees valid RESET and RESET output states down to VCC = 1V. At VCC = 1V, the active-low RESET output remains a guaranteed logic low (≤0.3V) with 50µA sink capability, and the active-high RESET output is valid down to VCC = 1.1V. This enables reliable supervision during deep brownout or battery-depleted conditions in portable systems.

How is the manual-reset input (MR) debounced on the MAX707CPA?

The MAX707CPA implements hardware debounce for the MR input via a 250µA internal pull-up current and a minimum 140ms reset pulse width. When MR is pulled low (e.g., by a pushbutton), the resulting RESET pulse lasts ≥140ms regardless of contact bounce duration-eliminating need for external RC filters or firmware debouncing. MR accepts TTL/CMOS logic levels and tolerates input voltages from 0V to VCC.

What is the function of the PFI and PFO pins on the MAX707CPA?

PFI is the power-fail input, connected to an internal 1.25V comparator reference; when voltage at PFI drops below 1.25V, PFO (power-fail output) pulls low. PFO is an open-drain output capable of sinking ≥3.2mA, allowing direct connection to µP interrupt lines or external pull-ups. This pair enables early-warning detection of supply collapse on +5V, +12V, or negative rails using simple resistor dividers-without requiring additional comparators.