Analog Devices Inc./Maxim Integrated MAX6865UK25D6S+T

Overview

The MAX6865UK25D6S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.5V reset threshold (±2.5%), and 1200ms minimum reset timeout period. It integrates voltage monitoring, manual reset input (MR), and watchdog timer with 209s typical timeout, and asserts active-high push-pull RESET during VCC brownout, MR assertion, or watchdog expiration - used in battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK25D6S+T datasheet, MAX6865UK25D6S+T pinout, MAX6865UK25D6S+T application, or MAX6865UK25D6S+T equivalent, this page delivers verified technical context, pin-level design meaning, real-world use cases, and validated alternative options for low-power µP reset supervision in space-constrained, long-life embedded systems.

Technical Context

The MAX6865UK25D6S+T implements a dual-trigger reset architecture: VCC monitoring with guaranteed validity down to 1.1V, and a watchdog timer that expires if WDI remains static beyond 209s (typ). Its internal 10kΩ MR pullup and glitch rejection (200ns) enable robust manual reset without external components.

It uses BiCMOS process technology (2848 transistors) and features temperature-stable reset threshold (±0.5%VTH hysteresis) and normalized tRP variation <±1% over –40°C to +85°C. The active-high push-pull RESET output sources ≥500µA at VCC ≥2.38V while maintaining VOH ≥0.8×VCC.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, 2.9mm × 1.6mm footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK25D6S+T, MAX6864UK25D6S+T removes watchdog functionality while retaining identical reset behavior and ultra-low ICC, whereas TPS3837K25DBVR trades 10× higher supply current for broader vendor support and simplified qualification - making MAX6865UK25D6S+T optimal for multi-year battery-critical medical wearables.

Availability

MAX6865UK25D6S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered IoT sensors, and low-power industrial loggers requiring stable component supply across extended product lifecycles.

Supply support for MAX6865UK25D6S+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, medical, and communications applications.

The MAX6865UK25D6S+T belongs to the nanopower µP supervisory family targeting ultra-long-life battery-operated equipment, with emphasis on guaranteed low-voltage reset validity and integrated watchdog supervision.

FAQ

What is the exact reset threshold voltage of the MAX6865UK25D6S+T?

The MAX6865UK25D6S+T has a factory-trimmed reset threshold of 2.500V with ±2.5% tolerance over –40°C to +85°C, as defined by the "25" suffix in its part number per Maxim's Threshold Suffix Guide. This value is guaranteed by design and does not require external calibration. The device asserts RESET when VCC falls below this threshold and maintains assertion for the full D6 timeout period (600–1200ms) after VCC rises above it. The MAX6865UK25D6S+T also provides 0.5%VTH hysteresis to prevent chatter near threshold crossing.

Does the MAX6865UK25D6S+T support active-high or active-low reset output?

The MAX6865UK25D6S+T features an active-high push-pull RESET output, as confirmed by its pin description (Pin 1 = RESET, "Active-High Push-Pull Reset Output") and Selector Guide entry. When asserted, RESET drives high to VCC; when deasserted, it drives low. This eliminates the need for an external pullup resistor and simplifies interfacing with µPs requiring high-active reset inputs. The MAX6865UK25D6S+T does not offer open-drain or active-low variants - those are assigned to other members of the MAX686x family such as MAX6866.

What is the watchdog timeout behavior of the MAX6865UK25D6S+T?

The MAX6865UK25D6S+T implements a watchdog timer with 209s typical timeout (L suffix), which expires if the WDI input remains static (high or low) beyond that duration. Each rising or falling edge on WDI clears the timer. The watchdog is disabled during RESET assertion and resumes counting only after RESET deasserts. This behavior is documented in the Electrical Characteristics table and functional diagram. Unlike some competitors, the MAX6865UK25D6S+T requires edge transitions-not level changes-to clear the watchdog, preventing false clears from stuck signals.

Can the MAX6865UK25D6S+T operate down to 1.1V supply voltage?

Yes, the MAX6865UK25D6S+T guarantees valid RESET assertion down to VCC = 1.1V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Below this voltage, RESET output drive capability degrades, but the device continues asserting RESET until VCC drops further. This feature ensures fail-safe behavior during deep brownout conditions common in battery discharge profiles. For applications requiring RESET validity all the way to 0V, a pulldown resistor on the push-pull RESET output is recommended - a design technique explicitly described in the Applications Information section for the MAX6865UK25D6S+T.

Is the MAX6865UK25D6S+T pin-compatible with other devices in the MAX686x family?

The MAX6865UK25D6S+T uses the standard 5-pin SOT23-5 package and shares identical pinout with MAX6864, MAX6866, MAX6867, MAX6868, and MAX6869 - Pin 1 = RESET, Pin 2 = GND, Pin 3 = MR, Pin 4 = WDI, Pin 5 = VCC. However, it is not pin-compatible with MAX6861/MAX6862/MAX6863 (which substitute CT for WDI) or MAX6854/MAX6855/MAX6856 (which lack WDI). This shared pinout enables layout reuse across watchdog-enabled variants, provided firmware and schematic account for the presence of WDI and active-high RESET.