Analog Devices Inc./Maxim Integrated MAX807MCWE+T

Overview

MAX807MCWE+T from Maxim Integrated is a full-featured microprocessor supervisory circuit designed for critical power monitoring in 5V µP systems. It provides ±1.5% accurate 4.425V reset threshold, active-low and active-high RESET outputs, manual reset input (MR), watchdog timer (1.6s timeout), and dual-mode backup-battery switchover (250mA VCC mode / 20mA battery mode). It ensures reliable system initialization and orderly shutdown in portable, industrial, and embedded controllers.

For engineers reviewing the MAX807MCWE+T datasheet, MAX807MCWE+T pinout, MAX807MCWE+T application, or MAX807MCWE+T equivalent, key selection considerations include its guaranteed RESET validity down to VCC = 1V, 2ns CE gate propagation delay, ±1.5% reset accuracy, two-stage low-line warning (52mV above reset threshold), and BATT OK status flag for 2.265V battery monitoring.

Technical Context

The MAX807MCWE+T integrates seven independent comparator functions: reset detection (4.425V ±1.5%), low-line warning (4.477V typical), power-fail input (2.265V threshold), battery-OK (2.265V), and watchdog timing (1.6s timeout). Its BiCMOS process enables 70µA supply current in normal operation and 1µA standby in battery-backup mode while maintaining precise voltage thresholds and fast propagation delays.

It implements dual-path power switching: VCC-to-OUT with 1.2Ω on-resistance (250mA) and BATT-to-OUT with 8.5Ω on-resistance (20mA), both guaranteed functional at VCC ≥1V. The chip-enable gating circuit features 2ns propagation delay (50Ω source, 50pF load) and automatic disable during reset assertion to prevent RAM corruption.

Key Specifications

Pinout & Package

MAX807MCWE+T is housed in a 16-pin TSSOP package (4.4mm × 5.0mm, 0.65mm pitch), optimized for space-constrained PCB layouts while maintaining thermal performance up to +85°C ambient.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX807MCWE+T, MAX809SCHEXK+T lacks supervision depth (no watchdog, no low-line warning), while TPS3808G33DBVR operates at incompatible voltage (3.3V vs. 4.425V) and omits battery management-making MAX807MCWE+T uniquely suited for 5V systems requiring full-feature power integrity and RAM retention.

Availability

MAX807MCWE+T is available at Aetrix Electronics and suitable for industrial controllers, portable medical devices, embedded test equipment, and automotive infotainment modules requiring stable component supply and long-term lifecycle support.

Supply support for MAX807MCWE+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) is a semiconductor company specializing in precision analog, mixed-signal, and power management ICs for demanding industrial, automotive, and computing applications.

The MAX807 product line delivers full-featured µP supervision-including reset, watchdog, battery switchover, and CE gating-for mission-critical 5V embedded systems where reliability, accuracy, and multi-function integration are essential.

FAQ

What is the exact reset threshold voltage of the MAX807MCWE+T?

The MAX807MCWE+T has a nominal reset threshold of 4.425V with ±1.5% accuracy over temperature (-40°C to +85°C) and supply voltage. This value is specified for the 'M' variant per Maxim's datasheet revision 4, and guarantees deterministic reset assertion when VCC falls below this level during power-down or brownout conditions. The MAX807MCWE+T maintains this accuracy without external calibration.

Does the MAX807MCWE+T support battery-backed RAM retention, and what are its drive limits?

Yes, the MAX807MCWE+T supports battery-backed RAM retention via its integrated BATT-to-OUT switchover circuit. In battery-backup mode, it delivers up to 20mA at ≤2.8V input, with BATT-to-OUT on-resistance of 8.5Ω (typical). The MAX807MCWE+T also provides a BATT OK flag to confirm battery voltage exceeds 2.265V before switchover, preventing data loss due to marginal battery charge.

How does the watchdog timer function in the MAX807MCWE+T, and how is it reset?

The MAX807MCWE+T watchdog timer has a 1.6s typical timeout period. It resets on any edge (low-to-high or high-to-low) at the WDI pin while RESET is deasserted. If no transition occurs within the timeout, WDO goes low. Connecting WDO to MR generates an automatic 200ms reset pulse. The MAX807MCWE+T watchdog is disabled when VCC falls below 4.35V or when WDI is left floating (internally biased to 1.8V).

Can the MAX807MCWE+T monitor power supplies other than +5V, and how is this implemented?

Yes, the MAX807MCWE+T can monitor non-5V supplies using its dedicated PFI input, which compares against a fixed 2.265V threshold. By configuring a resistor divider between the target supply and PFI, users set custom trip points-for example, monitoring a 3.3V rail with a 1.21kΩ/2.43kΩ divider. The MAX807MCWE+T's PFO output then signals degradation, enabling NMI-driven shutdown regardless of the main VCC rail voltage.

What is the purpose of the LOW LINE output, and how does it differ from the RESET output?

The LOW LINE output provides early warning of impending power failure-triggering when VCC falls to 52mV above the 4.425V reset threshold (i.e., at ~4.477V). Unlike RESET, which halts µP execution, LOW LINE asserts a non-maskable interrupt (NMI) to initiate firmware-controlled shutdown (e.g., saving EEPROM data). The MAX807MCWE+T guarantees ±13mV hysteresis on LOW LINE to prevent chatter during slow VCC decay.