Analog Devices Inc./Maxim Integrated MAX6822VUK+T

Overview

MAX6822VUK+T from Maxim Integrated is a low-voltage microprocessor supervisory IC in SOT23-5 package, featuring open-drain active-low RESET output, 1.58V reset threshold (V suffix), 140ms minimum reset timeout, 1.6s watchdog timer, and debounced manual reset input. It monitors power rails in battery-powered embedded controllers and intelligent instruments to prevent code-execution errors during brownout or startup.

For engineers reviewing the MAX6822VUK+T datasheet, MAX6822VUK+T pinout, MAX6822VUK+T application, or MAX6822VUK+T equivalent, this page delivers verified functional identity, exact pin roles, real-world timing behavior, supply-voltage margining down to +1.0V, and validated alternatives for critical µP monitoring designs.

Technical Context

The MAX6822VUK+T implements a precision bandgap-based voltage monitor with 60ppm/°C temperature coefficient and 2×VTH hysteresis, ensuring stable reset assertion across -40°C to +125°C. Its internal 1.6s watchdog timer clears on any WDI edge and remains disabled if WDI is left unconnected or three-stated.

Reset assertion occurs when VCC falls below 1.58V (±3% over temp), MR is pulled low, or WDI stalls; RESET remains low for ≥140ms after recovery. The open-drain RESET output supports bidirectional µP reset pins (e.g., Motorola 68HC11) with external pull-up, enabling shared reset bus architectures.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5 (U5-1 outline, land pattern 91-0174), RoHS-compliant, surface-mountable with 1.3mm × 2.9mm footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6822VUK+T, MAX6822TUK+T offers identical supervision architecture but targets higher-voltage rails, while TPS3808G15DBVR reduces feature count to lower cost and quiescent current-but sacrifices MR/WDI flexibility and open-drain interoperability.

Availability

MAX6822VUK+T is available at Aetrix Electronics and suitable for embedded controllers, portable/battery-powered equipment, and intelligent instruments requiring stable component supply with guaranteed long-term manufacturability.

Supply support for MAX6822VUK+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 demanding industrial, computing, and communications applications.

The MAX6821–MAX6825 family was engineered specifically for low-voltage µP supervision in space-constrained, battery-sensitive systems-emphasizing guaranteed operation down to +1.0V and integrated watchdog/manual reset in SOT23-5.

FAQ

What is the exact reset threshold voltage of MAX6822VUK+T and how tightly is it specified?

The MAX6822VUK+T has a factory-trimmed reset threshold of 1.58V, with tolerance of ±3% over the full -40°C to +125°C temperature range. This value is confirmed in the Electrical Characteristics table under "MAX682_V" row, with min/typ/max values of 1.52V/1.58V/1.62V. The threshold exhibits 60ppm/°C temperature coefficient and 2×VTH hysteresis, ensuring stable trip points across operating conditions. MAX6822VUK+T maintains this specification without external calibration.

Does MAX6822VUK+T support operation below 1.8V, and what is its minimum functional VCC?

Yes, MAX6822VUK+T operates down to +1.2V over temperature and guarantees valid RESET assertion down to +1.0V-verified in Absolute Maximum Ratings and Electrical Characteristics. At VCC = +1.2V, the device monitors its own supply and asserts open-drain RESET correctly with VOL ≤0.3V at ISINK = 50µA. This capability enables use in ultra-low-power 1.2V logic domains and deep brownout recovery scenarios where other supervisors fail. MAX6822VUK+T remains fully functional across this extended range.

How does the watchdog timer in MAX6822VUK+T respond to software faults, and what is its timeout behavior?

The MAX6822VUK+T watchdog timer has a nominal timeout of 1.6s (range 0.8s–2.6s over temperature) and clears only on rising or falling edges at WDI-not on static high/low states. If software hangs and fails to toggle WDI, reset asserts for ≥140ms. The timer remains cleared while RESET is active and begins counting anew upon RESET release. This edge-sensitive mechanism prevents stuck-loop evasion. MAX6822VUK+T's WDI accepts pulses as short as 50ns, enabling minimal GPIO overhead.

Can MAX6822VUK+T drive a reset line shared with other devices, and what is required for proper interfacing?

Yes, MAX6822VUK+T's open-drain RESET output is explicitly designed for wired-OR reset busing. To share the line, connect all RESET outputs to a common net with a single pull-up resistor (typically 4.7kΩ to VCC). No level-shifting or isolation is needed. The device sinks ≥50µA at VCC ≥1.0V, ensuring solid low-state drive. MAX6822VUK+T interfaces directly with bidirectional µP reset pins (e.g., Motorola 68HC11) without additional components-verified in Applications Information Figure 4.

Is manual reset functionality available on MAX6822VUK+T, and how is it implemented electrically?

Yes, MAX6822VUK+T includes a dedicated active-low MR input (Pin 3) with internal 50kΩ pullup to VCC. Pulling MR ≤0.3×VCC asserts RESET for ≥140ms after release. The input rejects <100ns glitches and requires only a momentary switch to GND-no external debounce. MR remains functional down to VCC = +1.2V, and leakage is <1µA when unused. MAX6822VUK+T supports both hardware-initiated and logic-driven reset events without added circuitry.