Analog Devices Inc./Maxim Integrated MAX6822RUK+T

Overview

MAX6822RUK+T from Maxim Integrated is a low-voltage microprocessor supervisory IC in SOT23-5 package, featuring open-drain active-low RESET output, 2.63V reset threshold (suffix R), 140ms minimum reset timeout, and 1.6s watchdog timer - used to ensure reliable power-up sequencing and fault recovery in embedded controllers and portable equipment.

For engineers reviewing the MAX6822RUK+T datasheet, MAX6822RUK+T pinout, MAX6822RUK+T application, or MAX6822RUK+T equivalent, this page delivers verified functional identity, exact pin roles, real-world timing behavior, and validated alternative options for µP reset and watchdog supervision in battery-powered and industrial systems.

Technical Context

The MAX6822RUK+T integrates voltage monitoring, manual reset input (MR), and watchdog timer (WDI) in a single 5-pin SOT23 device. It asserts open-drain RESET when VCC falls below 2.63V (±3% over –40°C to +125°C), holds it for ≥140ms after VCC recovers, and triggers reset if WDI remains static beyond 1.6s.

Its MR input includes internal 50kΩ pullup and 200ns MR-to-reset delay; WDI accepts CMOS-level edges with 50ns pulse-width tolerance; RESET remains valid down to VCC = +1.0V, enabling operation during deep brownout conditions.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5 (U5-1 outline, 21-0057 land pattern), RoHS-compliant, lead-free (+T suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6822RUK+T, MAX6823RUK+T provides identical supervision logic but requires board-level changes for reset signal routing, while TPS3808G33DBVR omits two core features (MR and WDI), limiting its use to non-critical power-good detection.

Availability

MAX6822RUK+T is available at Aetrix Electronics and suitable for set-top boxes, portable/battery-powered equipment, and embedded controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6822RUK+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 industrial, automotive, and computing applications, with emphasis on reliability and integration.

The MAX6821–MAX6825 family was engineered specifically for low-voltage microprocessor supervision in space-constrained, battery-sensitive, and thermally demanding systems - delivering integrated reset, watchdog, and manual reset in a 5-pin SOT23.

FAQ

What is the exact reset threshold voltage of MAX6822RUK+T and how tightly is it specified?

The MAX6822RUK+T has a factory-trimmed reset threshold of 2.63V, with guaranteed tolerance of ±3% over the full operating temperature range (–40°C to +125°C). This value is confirmed in the Threshold Suffix Guide and Electrical Characteristics table, where min/max limits are 2.53V to 2.72V at –40°C to +125°C. The MAX6822RUK+T uses the 'R' suffix to denote this specific threshold, and it is laser-trimmed during production - no external adjustment is needed or supported.

Does MAX6822RUK+T support operation during deep brownout, and down to what VCC level does RESET remain valid?

Yes, MAX6822RUK+T guarantees correct RESET output state down to VCC = +1.0V, as explicitly stated in the General Description and Electrical Characteristics. This means the device continues asserting RESET (low) even when supply voltage collapses below typical logic thresholds - ensuring safe microprocessor halt during severe brownout. Operation is fully specified from +1.2V to +5.5V, with functional reset assertion maintained at +1.0V.

How does the watchdog timer in MAX6822RUK+T interact with the manual reset input (MR)?

In MAX6822RUK+T, asserting MR low immediately triggers RESET assertion and simultaneously clears the internal 1.6s watchdog timer. RESET remains active for the full 140ms minimum timeout period after MR returns high - independent of watchdog state. The watchdog timer only runs when MR is inactive (high) and WDI is toggled; it does not interfere with MR-initiated resets, nor does MR disable the watchdog - both functions operate concurrently and independently.

Can MAX6822RUK+T interface directly with microcontrollers that have bidirectional reset pins, such as the Motorola 68HC11?

Yes, MAX6822RUK+T's open-drain RESET output is specifically designed for this purpose. Its open-drain architecture allows direct connection to bidirectional µP reset pins using only a single external pullup resistor - enabling either the MAX6822RUK+T or the µP itself to assert reset on the shared line. This capability is documented in the Applications Information section and illustrated in Figure 4 of the datasheet.

What is the maximum allowable leakage current on the WDI pin when left unconnected in MAX6822RUK+T?

When WDI is left unconnected in MAX6822RUK+T, the maximum allowable leakage current is 10µA, and the maximum load capacitance is 200pF - as specified in the Applications Information section. This condition disables the watchdog function, since the internal driver cycles low-high-low every ~1.4s to service the timer. Exceeding 10µA leakage may prevent reliable watchdog disablement and cause unintended resets.