Analog Devices Inc./Maxim Integrated MAX804TCPA

Overview

MAX804TCPA 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, watchdog timer (1.6s), and battery-backup switchover. It monitors VCC, asserts reset during power-up/brownout/watchdog timeout, and switches VOUT to VBATT when VCC falls below 2.40V - used in battery-backed embedded controllers requiring reliable power sequencing and RAM retention.

For engineers reviewing the MAX804TCPA datasheet, MAX804TCPA pinout, MAX804TCPA application, or MAX804TCPA equivalent, this page delivers verified specifications, validated pin functions, confirmed use cases in portable instrumentation and critical µP monitoring, and two technically documented alternative parts with explicit tolerance and functional distinctions.

Technical Context

The MAX804TCPA integrates a precision reset comparator with ±2% threshold accuracy (3.075V nominal), a non-disableable 1.6s watchdog timer cleared by WDI edges, and a dual-path power-switching architecture: VCC-to-VOUT via 3Ω PMOS and VBATT-to-VOUT via 140Ω switch. Its PFI input accepts external voltage dividers for auxiliary supply monitoring, while PFO provides active-low power-fail signaling.

Reset assertion is guaranteed down to VCC = 1V (with VBATT > 1V), and the device supports battery voltages exceeding VCC (e.g., 3.6V Li-cell). The manual reset input (MR) features internal 70µA pull-up and 200ms deassertion delay, and all logic inputs (WDI, MR, PFI) are compatible with TTL/CMOS levels.

Key Specifications

Pinout & Package

MAX804TCPA is housed in an 8-pin plastic DIP (PDIP) package with 0.3-inch body width and through-hole mounting. Pin spacing conforms to JEDEC MS-001, and the package is RoHS-compliant (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 MAX804TCPA, MAX804TSA offers identical supervision performance in a surface-mount form factor for modern production, while MAX805TCPA provides pin-compatible active-low reset output - both eliminate redesign effort but address distinct mechanical and interface constraints.

Availability

MAX804TCPA is available at Aetrix Electronics and suitable for battery-powered computers and controllers, intelligent instruments, and critical µP power monitoring requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.

Supply support for MAX804TCPA 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, computing, and communications markets.

The MAX804 series belongs to Maxim's microprocessor supervisory product line, designed specifically for robust power monitoring and fail-safe reset generation in 3.0V/3.3V embedded systems with battery backup requirements.

FAQ

What is the reset threshold voltage of the MAX804TCPA?

The MAX804TCPA has a nominal reset threshold voltage of 3.075V, with ±2% accuracy over temperature. This value is specified for VCC falling and rising conditions, and it ensures reset assertion occurs before the 3.3V supply drops below 3.0V - critical for systems with ±5% power tolerance. The 'T' suffix explicitly denotes this 3.075V variant.

Does the MAX804TCPA support battery voltages higher than VCC?

Yes, the MAX804TCPA explicitly supports VBATT exceeding VCC - for example, a 3.6V lithium coin cell can be connected to VBATT while VCC is at 3.3V. The internal battery switchover circuit activates when VCC falls below 2.40V, connecting VBATT to VOUT regardless of the voltage difference, enabling reliable RAM backup without external diodes.

How does the watchdog timer in the MAX804TCPA operate?

The MAX804TCPA incorporates a non-disableable 1.6s watchdog timer that triggers reset if the WDI input remains static (high or low) for longer than its timeout period. The timer clears on any edge (rising or falling) at WDI, making it responsive to µP heartbeat signals. Unlike older families, this watchdog cannot be disabled - ensuring continuous fault detection.

Can the MAX804TCPA be used without a backup battery?

Yes, but with configuration: connect both VBATT and VOUT pins directly to VCC. The MAX804TCPA is designed for battery-backed operation, so omitting the battery requires this wiring to prevent undefined behavior. For battery-less applications, Maxim recommends alternatives like the MAX706T/S/R, which lack battery switchover circuitry entirely.

What is the function of the PFI and PFO pins on the MAX804TCPA?

The PFI (Power-Fail Input) pin accepts an external voltage - typically from a resistor divider - 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 interrupt-capable signal to the µP. PFO is open-drain and can also be wired to MR on compatible parts (e.g., MAX704) to trigger reset on auxiliary supply failure.