Analog Devices Inc./Maxim Integrated MAX6828TUT+

Overview

MAX6828TUT+ from Maxim Integrated is an ultra-low-voltage dual microprocessor supervisory circuit in SOT23-6 package, featuring open-drain active-low RESET output, manual reset input (MR), watchdog timer (1.6s timeout), and user-adjustable RESET IN threshold (0.63V typical). It monitors primary supply VCC (1.8V–5.0V) and secondary voltage via external resistor divider, with guaranteed reset validity down to VCC = +1.0V. Used in portable battery-powered systems requiring reliable brownout and watchdog protection.

For engineers reviewing the MAX6828TUT+ datasheet, MAX6828TUT+ pinout, MAX6828TUT+ application, or MAX6828TUT+ equivalent, this page delivers verified technical context, exact pin functions, real-world timing behavior (140ms min reset timeout), true design trade-offs between open-drain vs. push-pull outputs, and validated alternative parts for multivoltage µP monitoring.

Technical Context

The MAX6828TUT+ implements a dual-threshold supervision architecture: one factory-set VCC monitor (3.08V ±3% for T-suffix) and one high-impedance RESET IN input (0.63V threshold) for user-defined secondary voltage monitoring. Its internal 1.6s watchdog timer clears on any WDI edge and triggers reset if no transition occurs within timeout.

Reset assertion is OR-combined from VCC undervoltage, RESET IN undervoltage, MR low, or watchdog timeout; reset remains asserted for ≥140ms after all conditions clear. The open-drain RESET output requires an external pullup and supports bidirectional µP reset pins (e.g., Motorola 68HC11), unlike push-pull variants.

Key Specifications

Pinout & Package

Package: 6-pin SOT23-6, surface-mount, lead-free (indicated by '+' suffix), footprint compatible with industry-standard 6L-SOT23.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-supply microprocessor supervision applications.

Compared with MAX6828TUT+, MAX6827TUT+ offers identical supervision accuracy but mandates active-high reset infrastructure, while TPS3808G33DBVR reduces integration by omitting RESET IN and watchdog-making MAX6828TUT+ the only option supporting true dual-rail monitoring + watchdog in a single SOT23-6 package.

Availability

MAX6828TUT+ is available at Aetrix Electronics and suitable for portable/battery-powered equipment, embedded controllers, and intelligent instruments requiring stable component supply across extended temperature ranges (-40°C to +125°C).

Supply support for MAX6828TUT+ 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 high-reliability industrial and automotive solutions.

The MAX6826–MAX6831 family was engineered specifically for space-constrained, multivoltage embedded systems needing integrated dual-supply monitoring, manual reset, and watchdog functionality in ultra-small SOT23-6 packages.

FAQ

What is the exact VCC reset threshold voltage for MAX6828TUT+?

The MAX6828TUT+ has a factory-trimmed VCC reset threshold of 3.08V, with ±3% tolerance over -40°C to +125°C. This value is specified in the Electrical Characteristics table under "MAX68__T" suffix and corresponds to the "T" in MAX6828TUT+. It is designed for reliable supervision of standard 3.3V power rails.

Does MAX6828TUT+ support monitoring a 1.2V secondary supply?

Yes, MAX6828TUT+ supports monitoring a 1.2V secondary supply using its RESET IN pin. With a typical threshold of 0.63V, a resistor divider (e.g., R1 = 90.9kΩ, R2 = 100kΩ) scales 1.2V down to ~0.63V at RESET IN. The device's high-impedance input (±100nA leakage) ensures minimal loading on the divider network.

Why does MAX6828TUT+ use an open-drain RESET output instead of push-pull?

MAX6828TUT+ uses an open-drain RESET output to enable direct interfacing with microcontrollers that have bidirectional reset I/O pins (e.g., Motorola 68HC11), support wired-OR reset bus topologies, and allow flexible pullup voltage selection. This architecture avoids contention when multiple devices drive the same reset line-a key requirement in complex embedded systems.

What is the minimum pulse width required on the WDI pin to prevent reset assertion in MAX6828TUT+?

The MAX6828TUT+ requires a minimum WDI pulse width of 50ns to reliably clear the internal watchdog timer. This specification is guaranteed by design (not production tested) and applies to both rising and falling edges. Pulses shorter than 50ns may fail to reset the timer, leading to unintended system reset after the 1.6s timeout period.

Can MAX6828TUT+ operate correctly when VCC drops below 1.8V?

Yes, MAX6828TUT+ is guaranteed to assert a valid reset down to VCC = +1.0V, per Absolute Maximum Ratings and Electrical Characteristics. Its internal circuitry remains functional and the open-drain RESET output maintains proper logic state even at 1.0V, making it suitable for deep-brownout scenarios where other supervisors fail.