Analog Devices Inc./Maxim Integrated MAX6821YUK

Overview

MAX6821YUK from Maxim Integrated is a low-voltage microprocessor supervisory IC in SOT23-5 package, providing voltage monitoring (2.19V threshold), 140ms minimum reset timeout, 1.6s watchdog timer, manual reset input, and push-pull active-low RESET output. It ensures reliable µP initialization during power-up, brownout, and code faults in embedded controllers and portable equipment.

For engineers reviewing the MAX6821YUK datasheet, MAX6821YUK pinout, MAX6821YUK application, or MAX6821YUK equivalent, this page delivers verified functional identity, exact reset threshold (2.19V), guaranteed reset validity down to VCC = +1.0V, watchdog timing behavior, and validated alternative options for critical µP monitoring designs.

Technical Context

The MAX6821YUK integrates a precision voltage comparator with 60ppm/°C temperature coefficient, a monostable reset timeout generator (140–320ms), and a watchdog timer with 1.6s nominal timeout (0.8–2.6s over temperature). Its internal 50kΩ MR pullup and glitch-rejecting input circuitry enable robust manual reset triggering without external components.

RESET assertion is synchronized to VCC falling below 2.19V (±1% at -40°C to +125°C), with propagation delay under 20µs and guaranteed valid output state down to VCC = +1.0V. The push-pull RESET output drives low with VOL ≤ 0.4V at 3.2mA and high with VOH ≥ 0.8×VCC at 800µA, supporting direct interface to µP reset pins.

Key Specifications

Pinout & Package

MAX6821YUK is housed in a 5-pin SOT23-5 package (JEDEC MO-178AA), 2.9mm × 1.6mm × 1.1mm, with gull-wing leads and exposed pad not connected internally.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6821YUK, MAX6326YUT+T removes watchdog and MR to reduce cost and quiescent current further, while TPS3808G18DBVR trades integrated fault coverage for tighter threshold tolerance and deeper low-VCC support-neither offers the complete supervision stack of voltage, watchdog, and manual reset in one SOT23-5 device.

Availability

MAX6821YUK is available at Aetrix Electronics and suitable for embedded controllers, portable/battery-powered equipment, automotive systems, and critical µP monitoring requiring stable component supply across extended temperature ranges.

Supply support for MAX6821YUK 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, sensing, and interface applications, with emphasis on reliability and integration.

The MAX6821–MAX6825 family was engineered specifically for space-constrained, low-voltage microprocessor systems needing combined voltage supervision, watchdog protection, and manual reset-all in a 5-pin SOT23 package.

FAQ

What is the exact reset threshold voltage for MAX6821YUK?

The MAX6821YUK has a factory-trimmed reset threshold of 2.19V, specified as 2.11V to 2.27V over the full -40°C to +125°C temperature range. This value corresponds to the "Y" suffix in the part number and is guaranteed by production testing-not just design simulation-ensuring accurate brownout detection for 2.2V logic supplies. The MAX6821YUK's 60ppm/°C temperature coefficient maintains stability across operating conditions.

Does MAX6821YUK include a watchdog timer, and what is its timeout behavior?

Yes, the MAX6821YUK includes a watchdog timer with a nominal timeout of 1.6 seconds, varying from 0.8s to 2.6s across -40°C to +125°C. The timer resets on any rising or falling edge at the WDI pin and remains cleared while RESET is asserted. If WDI is left unconnected, the internal driver disables the watchdog function. This behavior is confirmed in the Selector Guide and Electrical Characteristics table for MAX6821YUK.

What type of RESET output does MAX6821YUK provide, and how is it driven?

The MAX6821YUK provides an active-low push-pull RESET output. When asserted, it drives low with VOL ≤ 0.4V at 3.2mA sink current; when released, it drives high with VOH ≥ 0.8×VCC at 800µA source current. Unlike open-drain variants, this eliminates the need for an external pullup resistor and ensures fast, rail-to-rail transitions-critical for reliable µP reset signaling. This configuration is explicitly assigned to MAX6821 in the Pin Description and Selector Guide.

Can MAX6821YUK operate reliably at VCC = +1.0V, and what functions remain active?

Yes, the MAX6821YUK guarantees correct RESET output state (asserted or de-asserted per conditions) down to VCC = +1.0V, as stated in the General Description and confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables. At this voltage, the reset comparator, timeout timer, and MR input remain fully functional-enabling safe operation during ultra-low-power wake-up or deep brownout recovery sequences where other supervisors fail.

How is the manual reset input (MR) implemented on MAX6821YUK, and what external components are needed?

The MAX6821YUK includes an internal 50kΩ pullup resistor on the MR pin, allowing direct connection of a momentary switch from MR to GND-no external resistor or capacitor required. MR is active-low with VIH = 0.7×VCC and VIL = 0.3×VCC, and it rejects glitches <100ns. The MR-to-RESET delay is 200ns, and reset remains active for ≥140ms after MR returns high. These parameters are measured and specified in the Electrical Characteristics table for MAX6821YUK.