Analog Devices Inc./Maxim Integrated MAX807NCUE+T

Overview

MAX807NCUE+T from Maxim Integrated is a full-featured microprocessor supervisory circuit designed for power monitoring, battery switchover, and watchdog protection in 5V µP systems. It provides ±1.5% reset threshold accuracy (4.575V), 200ms reset timeout, active-low and active-high RESET outputs, independent watchdog timer (1.6s timeout), and 250mA VCC-mode output drive capability. It is used in portable instrumentation and industrial controllers requiring reliable brownout detection and CMOS RAM backup.

For engineers reviewing the MAX807NCUE+T datasheet, MAX807NCUE+T pinout, MAX807NCUE+T application, or MAX807NCUE+T equivalent, key selection considerations include its dual RESET outputs, low-line comparator with 52mV offset above reset threshold, BATT OK flag, chip-enable gating with 2ns propagation delay, and guaranteed RESET validity down to VCC = 1V.

Technical Context

The MAX807NCUE+T integrates seven comparators - reset, low-line, power-fail, battery-OK, and three internal reference monitors - plus a state-machine-based watchdog timer and BiCMOS transmission gates for CE signal control. Its reset comparator uses precision bandgap reference and hysteresis (30mV typical) to ensure noise immunity during VCC transients.

It implements automatic power-source arbitration between VCC and VBATT via dual N-channel/P-channel pass transistors, delivering up to 250mA from VCC or 20mA from battery while maintaining <70µA supply current in normal operation and <1µA in battery-standby mode.

Key Specifications

Pinout & Package

MAX807NCUE+T is housed in a 16-pin TSSOP package (4.4mm × 5mm, 0.65mm pitch), optimized for high-density PCB layouts and reflow compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX807NCUE+T, the MAX809SCHEXK+T omits all advanced supervision features, while the TPS3808G33DBVR supports different voltage domains and adjustable timing but lacks integrated battery management and dual-reset architecture essential for robust 5V µP systems.

Availability

MAX807NCUE+T is available at Aetrix Electronics and suitable for portable instrumentation, industrial controllers, medical handhelds, and smart metering applications requiring stable component supply, long-term lifecycle support, and guaranteed parametric compliance.

Supply support for MAX807NCUE+T 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 power management, sensing, and interface applications in industrial, automotive, and computing markets.

The MAX807 belongs to Maxim's µP supervisory product line, engineered specifically for high-accuracy, multi-function power monitoring in battery-backed 5V microprocessor systems where reliability, low quiescent current, and deterministic timing are critical.

FAQ

What is the reset threshold voltage of the MAX807NCUE+T?

The MAX807NCUE+T has a nominal reset threshold of 4.575V with ±1.5% accuracy over temperature (−40°C to +85°C). This value is factory-trimmed and specified in the Electrical Characteristics table under VRST for the "N" variant. The threshold remains stable across VCC supply variations and ensures reliable µP hold-off until the 5V rail reaches specification.

Does the MAX807NCUE+T support battery backup for CMOS RAM?

Yes, the MAX807NCUE+T provides fully integrated battery backup switching. When VCC falls below the reset threshold and VBATT exceeds VCC − 0.25V, the device automatically connects OUT to BATT. It delivers up to 20mA in battery-backup mode and includes a dedicated BATT OK output that goes high when VBATT > 2.265V, confirming backup readiness before power loss.

How does the watchdog timer function in the MAX807NCUE+T?

The MAX807NCUE+T features an independent watchdog timer with a typical timeout period of 1.6 seconds. It monitors the WDI input for edges; if no transition occurs within that window, WDO asserts low. Connecting WDO to MR creates an automatic reset loop on timeout. The watchdog is disabled when VCC < reset threshold or when WDI is left floating (internally biased to 1.8V).

Can the MAX807NCUE+T gate chip-enable signals to protect memory during power failure?

Yes, the MAX807NCUE+T includes on-chip CE gating logic. During normal operation, CE IN passes directly to CE OUT with 2ns propagation delay. When RESET is asserted, the transmission gate disables and CE OUT is actively pulled to the higher of VCC or VBATT, preventing spurious writes to CMOS RAM or EEPROM during brownout or power-down sequences.

What is the purpose of the LOW LINE output on the MAX807NCUE+T?

The LOW LINE output on the MAX807NCUE+T is an active-low comparator signal triggered when VCC falls to 52mV above the reset threshold (e.g., ~4.627V for the N version). It provides a non-maskable interrupt (NMI) to initiate software-controlled shutdown before reset occurs, allowing time to save state or flush buffers - a critical capability for data integrity in portable and industrial systems.