Analog Devices Inc./Maxim Integrated MAX703EPA

Overview

MAX703EPA from Maxim Integrated is a microprocessor supervisory circuit designed for power-supply monitoring and battery-backup switching in embedded μP systems. It provides active-low reset during power-up/brownout (4.65V threshold), battery-switchover to CMOS RAM, 1.25V power-fail detection, and debounced manual reset - all in an 8-pin PDIP package rated for -40°C to +85°C operation.

For engineers reviewing the MAX703EPA datasheet, MAX703EPA pinout, MAX703EPA application, or MAX703EPA equivalent, key selection criteria include guaranteed RESET assertion down to VCC = 1V, 200ms reset pulse width, 50nA battery-backup quiescent current, and precise 4.65V supply-voltage monitor with 40mV hysteresis.

Technical Context

The MAX703EPA integrates four core functions: a precision voltage-monitoring comparator with fixed 4.65V reset threshold, a battery-switchover circuit using p-channel MOSFETs (5Ω on VCC path, 80Ω on VBATT path), a 1.25V reference-based power-fail comparator with PFI/PFO interface, and TTL/CMOS-compatible manual reset input with internal 250µA pullup.

Its reset generator asserts active-low RESET for ≥140ms (typ. 200ms) after VCC rises above threshold or MR transitions low-to-high; RESET remains valid even as VCC falls to 1V, and the device enters ultra-low-power battery-backup mode (<1µA) when VCC drops >1V below VBATT.

Key Specifications

Pinout & Package

MAX703EPA is housed in an 8-pin plastic dual in-line package (PDIP), compatible with through-hole assembly and legacy socket designs. The package meets RoHS requirements and supports leaded or lead-free soldering (lead-free version denoted by '+' suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX703CPA, MAX703EPA adds extended temperature support essential for industrial deployment; compared with MAX705CPA, it trades watchdog and write-protect features for dedicated battery-switching circuitry optimized for long-term RAM retention.

Availability

MAX703EPA is available at Aetrix Electronics and suitable for industrial controllers, medical instrumentation, and automotive infotainment systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX703EPA 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, communications, and computing applications.

The MAX703 product line delivers cost-optimized, integrated supervisory solutions for μP-based systems needing reliable power monitoring, reset control, and battery-backed memory preservation - with emphasis on simplicity, low quiescent current, and robust operation across harsh environments.

FAQ

What is the guaranteed reset assertion voltage range for MAX703EPA?

The MAX703EPA guarantees active-low RESET assertion down to VCC = 1V, ensuring deterministic microprocessor reset behavior even during severe brownout conditions. This specification holds across the full -40°C to +85°C operating temperature range and is validated per the Absolute Maximum Ratings and Electrical Characteristics tables in the official datasheet. The MAX703EPA continues to drive RESET low until VCC rises above 4.65V and sustains the 200ms reset pulse width.

Does MAX703EPA support lithium battery backup, and what is the maximum allowable VBATT voltage?

Yes, MAX703EPA supports lithium battery backup via its VBATT pin and internal switchover circuitry. The maximum allowable backup-battery voltage is 4.80V, as specified in Table 2 of the datasheet. Exceeding this voltage risks forward-biasing internal substrate diodes and causing unintended current flow from VBATT to VCC when voltages are closely matched - potentially compromising reset integrity or battery life.

How does the power-fail comparator (PFI/PFO) function in MAX703EPA, and is it active during battery backup?

The MAX703EPA's PFI input compares external voltage against a 1.25V internal reference; when PFI falls below threshold, PFO goes low. However, the power-fail comparator is explicitly disabled and PFO is forced low during battery-backup mode (i.e., when VCC drops below reset threshold and VBATT powers VOUT). This ensures no spurious interrupts occur while the system operates solely on backup power - a design feature confirmed in the "Detailed Description" and Table 1 sections of the datasheet.

What is the quiescent current of MAX703EPA in battery-backup mode, and how is it achieved?

In battery-backup mode (VCC = 0V, VBATT = 2.8V), MAX703EPA draws ≤5.0µA over temperature, with typical current of 50nA at +25°C. This ultra-low consumption is achieved by disabling non-essential circuitry including the power-fail comparator, manual reset input, and internal bias networks - leaving only the reset generator and switchover control active. The datasheet confirms this value in the "Electrical Characteristics" table under "ISUPPLY in Battery-Backup Mode".

Can MAX703EPA be used without a backup battery, and if so, how should VBATT be handled?

Yes, MAX703EPA can be used without a backup battery. In that case, VBATT must be grounded and VCC directly connected to VOUT (bypassing the internal switch) to eliminate voltage drop. The datasheet explicitly recommends this configuration in the "Using the MAX703/MAX704 without a Backup Power Source" section. Alternatively, designers may select the MAX705–MAX708 series, which omit battery-switching circuitry entirely and simplify layout for non-backup applications.