Analog Devices Inc./Maxim Integrated MAX6865UK38D2S+T

Overview

The MAX6865UK38D2S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 3.800V reset threshold (suffix "38"), 40ms minimum reset timeout (suffix "D2"), and integrated watchdog timer with 3.3s typical timeout (suffix "S"). It monitors VCC, responds to manual reset (MR), and asserts reset on voltage drop, MR assertion, or watchdog expiration - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK38D2S+T datasheet, MAX6865UK38D2S+T pinout, MAX6865UK38D2S+T application, or MAX6865UK38D2S+T equivalent, this page delivers verified functional identity, exact pin roles, confirmed timing parameters, real-world use cases, and validated alternative options - all grounded in Maxim's official datasheet Rev 4 (12/2005) and ordering documentation.

Technical Context

The MAX6865UK38D2S+T implements a dual-trigger reset architecture: it asserts reset when VCC falls below 3.800V ±2.5%, when MR is pulled low, or when the watchdog input (WDI) remains static beyond 3.3s (typ). Its internal timer guarantees reset remains asserted for ≥40ms after VCC recovers and MR deasserts.

Designed for ultra-low-power systems, it operates down to VCC = 1.1V with guaranteed RESET validity, features 200ns MR glitch rejection, and uses BiCMOS process (2848 transistors) to achieve 170nA typical ICC at +25°C - enabling multi-year operation on coin-cell batteries.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5 (lead-free, +T suffix), footprint-compatible with industry-standard 5-pin SOT23 layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK38D2S+T, MAX6864UK38D2S+T offers identical supervision timing but inverted reset polarity, while TPS3837K33DBVR trades nanopower efficiency and watchdog capability for lower unit cost and simpler design - making each suitable for distinct reliability and power budget constraints.

Availability

MAX6865UK38D2S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered instrumentation, and low-power embedded controllers requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK38D2S+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 power, sensing, and connectivity applications - with leadership in ultra-low-power supervision and battery management.

The MAX6854–MAX6869 family was engineered specifically for nanopower microprocessor supervision in space-constrained, battery-operated medical and portable electronics - prioritizing sub-µA quiescent current and guaranteed reset validity down to 1.1V.

FAQ

What is the exact reset threshold voltage of the MAX6865UK38D2S+T?

The MAX6865UK38D2S+T has a factory-trimmed reset threshold of 3.800V ±2.5%, as defined by the "38" suffix per Maxim's Threshold Suffix Guide (Table 2). This value is guaranteed over -40°C to +85°C and ensures reliable detection of brownout conditions in 3.3V systems where VCC may dip near 3.8V during transient loads. The MAX6865UK38D2S+T maintains this accuracy without external calibration.

Does the MAX6865UK38D2S+T require external components for basic operation?

No, the MAX6865UK38D2S+T operates autonomously with zero external components: it includes an internal 10kΩ pullup on MR, a precision voltage reference, and a temperature-compensated watchdog oscillator. Only a 0.1µF ceramic capacitor from VCC to GND is recommended for noise suppression - no resistors, capacitors, or additional ICs are needed for reset generation or watchdog supervision. This minimizes BOM count and PCB area for the MAX6865UK38D2S+T.

How does the watchdog timer in the MAX6865UK38D2S+T function?

The MAX6865UK38D2S+T watchdog timer expires if the WDI pin remains static (high or low) for longer than 3.3s (typical), triggering a reset pulse for the 40ms timeout period. The timer clears on any WDI edge (rising or falling), on MR assertion, or during active reset. It is immune to noise spikes <150ns and requires no external clock - making it ideal for supervising firmware loops in medical sensors. This behavior is intrinsic to the MAX6865UK38D2S+T's BiCMOS design.

What is the minimum VCC voltage at which the MAX6865UK38D2S+T guarantees valid reset output?

The MAX6865UK38D2S+T guarantees valid RESET output down to VCC = 1.1V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Below this voltage, the internal circuitry may not sustain proper logic levels; however, most target microprocessors cease operation above 1.1V, making this threshold sufficient for safe brownout response. This specification is tested and guaranteed - not typical - for the MAX6865UK38D2S+T across its full temperature range.

Is the MAX6865UK38D2S+T pin-compatible with other devices in the MAX68xx family?

Yes, the MAX6865UK38D2S+T shares the identical 5-pin SOT23-5 pinout with all MAX6864–MAX6869 variants (e.g., MAX6864, MAX6866), including matching VCC, GND, MR, WDI, and RESET assignments. This allows direct substitution within the same watchdog-enabled subgroup - though reset polarity (active-high vs. active-low) and timeout values must be verified per part number. Pin compatibility is explicitly confirmed in Maxim's Selector Guide and Pin Configurations section for the MAX6865UK38D2S+T.