Analog Devices Inc./Maxim Integrated MAX6828VUT+

Overview

MAX6828VUT+ from Maxim Integrated is an ultra-low-voltage dual-supply microprocessor supervisory IC in 6-pin SOT23 package, featuring open-drain active-low RESET output, manual reset (MR) input with internal 50kΩ pullup, watchdog timer (1.6s nominal timeout), and user-adjustable RESET IN threshold (0.63V typ). It monitors primary supply VCC (1.53V–2.0V range, factory-trimmed to 1.575V ±0.054V at -40°C to +125°C) and secondary supply via RESET IN for voltages down to 0.63V - used in battery-powered embedded controllers requiring reliable brownout detection and system-level reset coordination.

For engineers reviewing the MAX6828VUT+ datasheet, MAX6828VUT+ pinout, MAX6828VUT+ application, or MAX6828VUT+ equivalent, key selection considerations include its open-drain RESET output compatibility with bidirectional µP reset pins (e.g., Motorola 68HC11), guaranteed reset validity down to VCC = +1.0V, immunity to short negative VCC transients (<20µs at 100mV overdrive), and absence of external components required for basic operation.

Technical Context

The MAX6828VUT+ integrates two independent voltage monitoring paths: a factory-trimmed VCC threshold comparator (1.575V) and a high-impedance RESET IN input with 0.63V internal reference, enabling user-defined secondary voltage monitoring via resistor divider. Its watchdog circuit clears on any WDI edge and triggers reset if no transition occurs within 1.6s (min 0.80s, max 2.60s over temperature).

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 supports flexible pullup configurations and interfaces directly with µPs having bidirectional reset I/O without level-shifting.

Key Specifications

Pinout & Package

MAX6828VUT+ uses a 6-pin SOT23 package (outline U6+1, land pattern 90-0175), RoHS-compliant with lead-free plating (+T suffix). Pin 1 is marked by dot; pin numbering follows standard SOT23 top-view convention.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6826VUT+, MAX6828VUT+ provides open-drain flexibility for bidirectional reset interfaces; compared with MAX6831VUT+, it trades fixed VCC2 monitoring for adjustable RESET IN, enabling custom secondary voltage thresholds without component changes.

Availability

MAX6828VUT+ is available at Aetrix Electronics and suitable for portable/battery-powered equipment, embedded controllers, and intelligent instruments requiring stable component supply across industrial temperature ranges (-40°C to +125°C) and long-term production continuity.

Supply support for MAX6828VUT+ 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, and communications applications.

The MAX6826–MAX6831 family delivers dual-supply µP supervision in ultra-small SOT23 packages, targeting space-constrained, low-power systems where reliable power-on reset, brownout detection, and software watchdog functionality are essential.

FAQ

What is the exact VCC reset threshold voltage for MAX6828VUT+ and its tolerance over temperature?

The MAX6828VUT+ has a factory-trimmed VCC reset threshold of 1.575V (typical), with minimum 1.521V and maximum 1.629V over the full -40°C to +125°C operating range. This specification is guaranteed per the Electrical Characteristics table in the MAX6826–MAX6831 datasheet, and applies specifically to the 'V' suffix variant. The threshold exhibits 60ppm/°C temperature coefficient and 2×VTH hysteresis.

Does MAX6828VUT+ support monitoring a secondary voltage lower than 0.63V?

No, MAX6828VUT+ does not support monitoring voltages below its internal RESET IN comparator threshold of 0.63V (typical). The device's RESET IN pin is designed for user-adjustable monitoring of voltages ≥0.63V via external resistor divider; attempting to apply sub-threshold voltages results in no reset assertion. For sub-0.63V monitoring, alternative supervisors with lower reference voltages (e.g., MAX6361 series) must be selected.

How does the watchdog timer in MAX6828VUT+ interact with the manual reset (MR) input?

In MAX6828VUT+, the watchdog timer and manual reset (MR) input operate independently but share the same reset assertion logic. Pulling MR low forces immediate reset assertion regardless of watchdog state, and the reset remains active for the full timeout period (≥140ms) after MR returns high. During MR assertion, the watchdog timer is cleared and does not count; it resumes timing only after reset deassertion completes.

Can MAX6828VUT+ be used with a 5V microcontroller that has a bidirectional reset pin?

Yes, MAX6828VUT+ can interface with 5V µPs having bidirectional reset pins (e.g., Motorola 68HC11) using its open-drain RESET output. Connect MAX6828VUT+ pin 1 (RESET) directly to the µP reset pin with a single external pullup resistor to the µP's 5V supply. The open-drain structure prevents contention when the µP drives the line low, enabling safe bidirectional communication without level shifters or additional logic.

What is the maximum allowable leakage current on the RESET IN pin of MAX6828VUT+?

The RESET IN pin of MAX6828VUT+ has a guaranteed input current of ±100nA over the full -40°C to +125°C temperature range. This low leakage ensures minimal error in resistor-divider networks used to set secondary voltage thresholds, supporting accurate monitoring of voltages as low as 0.63V. The specification is documented in the Electrical Characteristics table under "RESET IN Input Current".