Analog Devices Inc./Maxim Integrated MAX6865UK26D4L+T

Overview

The MAX6865UK26D4L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.625V reset threshold (suffix '26'), 1200ms minimum reset timeout (suffix 'D4'), and 209s typical watchdog timeout (suffix 'L'). It monitors VCC, responds to manual reset (MR), and triggers reset on watchdog timeout (WDI), making it ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK26D4L+T datasheet, MAX6865UK26D4L+T pinout, MAX6865UK26D4L+T application, or MAX6865UK26D4L+T equivalent, key selection criteria include guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), push-pull active-high RESET output, and compatibility with noisy low-power systems requiring long watchdog intervals.

Technical Context

This device integrates three core functions: precision voltage monitoring with ±2.5% threshold accuracy over temperature, a configurable watchdog timer that clears on any WDI edge and expires after 209s (typ) if inactive, and a manual reset input with 250ns MR-to-reset delay and internal 10kΩ pullup. The reset assertion logic combines VCC undervoltage, MR assertion, and WDI timeout - all triggering the same push-pull active-high RESET output.

The internal architecture uses BiCMOS process (2848 transistors) to achieve nanoscale quiescent current while maintaining robust noise immunity: reset remains valid down to VCC = 1.1V, and the device rejects transients ≤40µs when VCC drops 100mV below threshold. No external components are required beyond standard 0.1µF VCC bypass.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SC-70/SOT-23 variants.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK26D4L+T, the MAX6865UK26D4L+T provides active-high reset polarity for direct µP compatibility, while TPS3837K26DBVR offers higher threshold accuracy but omits watchdog and long timeout - making MAX6865UK26D4L+T optimal for battery-powered medical devices requiring both supervision and fault recovery.

Availability

MAX6865UK26D4L+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitors, and portable ECG recorders requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK26D4L+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 timing applications in industrial, medical, and communications markets.

The MAX6854–MAX6869 family delivers nanopower supervisory functionality for battery-critical systems, emphasizing ultra-low ICC, wide VCC range, and integrated watchdog capability without external components.

FAQ

What is the exact reset threshold voltage of the MAX6865UK26D4L+T?

The MAX6865UK26D4L+T has a factory-trimmed reset threshold voltage of 2.625V, with ±2.5% tolerance over the -40°C to +85°C operating temperature range. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix '26' corresponds to 2.625V nominal. The device guarantees reset assertion when VCC falls below this threshold and maintains reset for the full 1200ms timeout after VCC rises above it.

Does the MAX6865UK26D4L+T require external components for basic operation?

No, the MAX6865UK26D4L+T requires no external components for core functionality. A 0.1µF ceramic capacitor from VCC to GND is recommended for noise suppression but not strictly required for specification compliance. The MR input features an internal 10kΩ pullup, and the push-pull active-high RESET output eliminates the need for external pullup resistors - enabling true "single-chip" supervision in space-constrained designs.

How does the watchdog timer in the MAX6865UK26D4L+T respond to software activity?

The MAX6865UK26D4L+T watchdog timer clears on any rising or falling edge at the WDI pin - not on level detection - which prevents infinite loops from masking faults. With a typical timeout of 209s (suffix 'L'), it allows long firmware execution windows while still detecting hangs. If WDI remains static beyond this period, the device asserts RESET for 1200ms, ensuring full µP restart. The timer pauses during RESET assertion and resumes counting immediately upon deassertion.

Can the MAX6865UK26D4L+T operate reliably during severe supply voltage sags?

Yes, the MAX6865UK26D4L+T guarantees valid reset assertion down to VCC = +1.1V, and its internal circuitry remains functional across the full 1.2V–5.5V supply range. Its transient immunity rejects VCC glitches under 40µs duration when overdrive is ≤100mV, as shown in the Typical Operating Characteristics graph (Figure MAX684 toc05). This ensures deterministic behavior during brownout and switching regulator noise events.

What is the pin compatibility status of the MAX6865UK26D4L+T with other devices in the family?

The MAX6865UK26D4L+T shares identical 5-pin SOT23 pinout (VCC, WDI, MR, GND, RESET) with MAX6864/MAX6866/MAX6867–MAX6869 variants. It is not pin-compatible with MAX6861–MAX6863 (which use CT instead of WDI) or MAX6854–MAX6860 (which lack WDI). The push-pull active-high RESET output matches MAX6865/MAX6868 pin-for-pin, enabling direct substitution where active-high reset polarity is required.