Analog Devices Inc./Maxim Integrated MAX806TEPA+

Overview

MAX806TEPA+ from Maxim Integrated is a 3.3V microprocessor supervisory circuit with active-high open-drain RESET output, 3.075V reset threshold, 200ms reset timeout, watchdog timer (1.6s), and battery-backup switchover. It monitors VCC supply integrity, asserts reset during brownout or watchdog timeout, and powers CMOS RAM from VBATT when VCC fails - used in embedded controllers and portable equipment requiring reliable power sequencing.

For engineers reviewing the MAX806TEPA+ datasheet, MAX806TEPA+ pinout, MAX806TEPA+ application, or MAX806TEPA+ equivalent, this page delivers verified specifications, validated pin functions, confirmed battery-switching behavior, exact reset timing under temperature, and real-world alternatives for 3.3V µP supervision with manual reset and power-fail warning capability.

Technical Context

The MAX806TEPA+ integrates a precision reset comparator with ±2% threshold tolerance (3.075V), a 1.6s watchdog timer that clears on WDI edge transitions, and a dual-path power switch: VCC-to-VOUT via 3Ω PMOS and VBATT-to-VOUT via 140Ω NMOS. Its PFI input accepts external voltage dividers for auxiliary supply monitoring, while PFO provides an independent low-active power-fail signal.

Unlike the MAX690 or MAX704 families, the MAX806TEPA+ features active-high open-drain RESET (requiring external pull-up), supports VBATT > VCC operation up to 6.0V, guarantees RESET assertion down to VCC = 1.0V, and maintains battery leakage below 1µA across –40°C to +85°C. The internal MR pull-up is 70µA, and WDI logic thresholds are referenced to 0.3×/0.7×VCC.

Key Specifications

Pinout & Package

MAX806TEPA+ is housed in an 8-pin plastic DIP (PDIP) package with 0.300" wide body, RoHS-compliant lead finish indicated by the '+' suffix. Pin spacing is 0.100", and thermal resistance is 9.09mW/°C above +70°C (727mW max at TA = +70°C).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX802TEPA+, MAX806TEPA+ adds manual reset and active-high reset polarity; compared with MAX706TEPA+, it adds battery switchover and watchdog - making MAX806TEPA+ the only choice among these three for battery-backed, watchdog-secured µP systems requiring field-reset capability.

Availability

MAX806TEPA+ is available at Aetrix Electronics and suitable for battery-powered computers and controllers, embedded controllers, intelligent instruments, and portable equipment requiring stable component supply with guaranteed long-term manufacturability.

Supply support for MAX806TEPA+ 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, mixed-signal, and power-management ICs for industrial, medical, communications, and computing applications.

The MAX806TEPA+ belongs to Maxim's µP supervisory family targeting 3.0V/3.3V systems, engineered to replace discrete reset circuits with integrated reset generation, watchdog supervision, battery switchover, and power-fail detection in space-constrained embedded designs.

FAQ

What is the function of the WDI pin on the MAX806TEPA+?

The WDI (Watchdog Input) pin on the MAX806TEPA+ monitors µP activity: if WDI remains static (high or low) for longer than 1.6 seconds, the internal watchdog timer expires and triggers a reset. The timer clears on any rising or falling edge at WDI. This function cannot be disabled, and WDI thresholds are 0.3×VCC (low) and 0.7×VCC (high). The MAX806TEPA+ relies on this pin to detect firmware lockups autonomously.

Does the MAX806TEPA+ support battery voltage higher than VCC?

Yes, the MAX806TEPA+ explicitly supports VBATT exceeding VCC - a key feature enabling direct connection of standard 3.6V lithium coin cells to the VBATT pin while VCC is at 3.3V. Switchover occurs when VCC falls below 2.40V (VSW), and the internal 140Ω switch connects VBATT to VOUT. This behavior is confirmed in the Absolute Maximum Ratings (VBATT: –0.3V to +6.0V) and Detailed Description sections of the MAX806TEPA+ datasheet.

What is the reset output type of the MAX806TEPA+?

The MAX806TEPA+ features an active-high, open-drain RESET output (Pin 7), distinct from the active-low RESET found on MAX690/MAX704 variants. It requires an external pull-up resistor to VCC to generate a valid logic-high signal. This output goes high only after the 200ms reset timeout completes and VCC rises above 3.075V. The MAX806TEPA+ datasheet confirms this configuration in the Pin Description and Typical Operating Circuits sections.

Can the MAX806TEPA+ operate without a backup battery?

Yes, the MAX806TEPA+ can operate without a backup battery: connect both VBATT and VOUT pins to VCC. However, doing so disables battery switchover and backup RAM functionality. The device continues to provide reset supervision, watchdog, and power-fail detection. The MAX806TEPA+ datasheet states this configuration is acceptable when battery backup is unnecessary, though alternative parts like MAX706TEPA+ may be more cost-optimized for such use cases.

What is the guaranteed minimum VCC voltage for RESET assertion in the MAX806TEPA+?

The MAX806TEPA+ guarantees RESET assertion (i.e., RESET output driven low in active state) for all VCC values from 0V up to the reset threshold of 3.075V - and specifically down to VCC = 1.0V, as stated in the Features list and Electrical Characteristics table. This ensures reliable reset initiation even during severe brownout conditions where VCC sags below typical logic thresholds, a critical capability for maintaining system integrity in unstable power environments.