Analog Devices Inc./Maxim Integrated MAX805TCPA+

Overview

MAX805TCPA+ from Maxim Integrated is a 3.3V microprocessor supervisory circuit with active-high open-drain RESET output, 3.075V reset threshold (T-suffix), 200ms reset timeout, 1.6s watchdog timer, and battery-backup switchover capability for CMOS RAM retention. It monitors VCC supply integrity, detects power-fail conditions via PFI/PFO, and supports manual reset input - deployed in embedded controllers and portable equipment requiring reliable brownout protection.

For engineers reviewing the MAX805TCPA+ datasheet, MAX805TCPA+ pinout, MAX805TCPA+ application, or MAX805TCPA+ equivalent, this page delivers verified technical context, exact pin functions, real-world use cases, and validated alternative parts - all grounded in Maxim's official specifications for the MAX805T family in 8-pin SO package with lead-free (+) marking.

Technical Context

The MAX805TCPA+ integrates a precision reset comparator with ±4% threshold tolerance (3.075V nominal), a 1.6s watchdog timer that clears on WDI edge transitions, and a dual-path power-switching architecture: VOUT connects to VCC above reset threshold and switches to VBATT when VCC falls below 2.40V (VSW), enabling seamless RAM backup during brownout. Its PFI input features 1.237V threshold with 10mV hysteresis for external power-rail monitoring.

It operates across 0°C to +70°C (C-grade), draws only 40µA typical VCC supply current at VCC < 3.6V, and guarantees RESET assertion down to VCC = 1V. The active-high RESET output is open-drain, requiring external pull-up; PFO is an active-low open-drain power-fail indicator; MR is internally pulled up (70µA) and debounced by the 200ms timeout.

Key Specifications

Pinout & Package

MAX805TCPA+ is housed in an 8-pin SOIC (Small Outline Integrated Circuit) package, RoHS-compliant with lead-free finish indicated by the '+' suffix. Pin spacing is 1.27mm, body width 3.9mm, and total package dimensions conform to JEDEC MS-012AA.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX805TSA+, MAX805TCPA+ offers higher reset threshold for tighter 3.3V supply monitoring; compared with MAX804TCPA+, it provides active-high reset signaling - simplifying interface to µPs with weak or no internal pull-up on reset I/O.

Availability

MAX805TCPA+ is available at Aetrix Electronics and suitable for battery-powered computers and controllers, intelligent instruments, and critical µP power monitoring applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for MAX805TCPA+ 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 markets.

The MAX805 series belongs to Maxim's microprocessor supervisory product line, designed specifically for reliable power monitoring, reset generation, and battery-switchover in 3.0V/3.3V embedded systems - emphasizing low quiescent current, precise thresholds, and integrated watchdog functionality.

FAQ

What is the reset threshold voltage of the MAX805TCPA+?

The MAX805TCPA+ has a nominal reset threshold voltage of 3.075V, with a tolerance of ±4% over temperature and supply variations. This value applies to both rising and falling VCC edges, though hysteresis ensures clean transition behavior. The 'T' in the part number explicitly denotes this 3.075V variant, and the threshold is guaranteed to assert reset before VCC falls below 3.00V and release reset after VCC rises above 3.17V.

Does the MAX805TCPA+ support battery backup for CMOS RAM?

Yes, the MAX805TCPA+ supports battery backup for CMOS RAM via its VOUT and VBATT pins. When VCC drops below the 2.40V switchover threshold (VSW), the internal 140Ω switch connects VBATT to VOUT, maintaining power to RAM. VBATT may exceed VCC (e.g., 3.6V Li-cell), and battery leakage is limited to 0.4–1µA - ensuring multi-year data retention without excessive drain on the backup source.

How does the watchdog timer function in the MAX805TCPA+?

The MAX805TCPA+ incorporates a 1.6s watchdog timer (1.12–2.24s range) that monitors the WDI pin. If WDI remains static (high or low) beyond this timeout, RESET is asserted. The timer clears on any edge transition (rising or falling) at WDI, enabling flexible software servicing. Unlike older families, the watchdog cannot be disabled - ensuring continuous fault coverage in safety-critical applications.

What is the purpose of the PFI and PFO pins on the MAX805TCPA+?

The PFI (Power-Fail Input) pin accepts a divided voltage from an auxiliary supply rail and compares it to a 1.237V internal reference. When PFI falls below this threshold, the PFO (Power-Fail Output) pin goes low - providing an active-low, open-drain signal usable for µP interrupts or cascaded reset triggering. PFO can also be connected to MR on compatible parts like MAX704 to generate a reset on power-fail events.

Is the MAX805TCPA+ pin-compatible with other members of the MAX80x family?

Yes, the MAX805TCPA+ shares identical 8-pin SOIC pinout and function mapping with MAX802T/S/R, MAX804T/S/R, and MAX806T/S/R - including VOUT, VCC, GND, PFI, PFO, WDI, RESET, and VBATT assignments. However, RESET polarity differs: MAX805TCPA+ provides active-high open-drain output, whereas MAX804TCPA+ offers active-low. No PCB changes are needed when substituting within same suffix (T/S/R) and package type.