Analog Devices Inc./Maxim Integrated MAX6865UK18D6L+T

Overview

The MAX6865UK18D6L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, a factory-trimmed 1.8V reset threshold (±2.5%), 1200ms minimum reset timeout, and integrated watchdog timer with 209s typical timeout. It monitors VCC, responds to manual reset (MR), and asserts an active-high push-pull RESET output - designed for reliable power-up/brownout protection in battery-critical systems like glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK18D6L+T datasheet, MAX6865UK18D6L+T pinout, MAX6865UK18D6L+T application, or MAX6865UK18D6L+T equivalent, key selection factors include its guaranteed reset validity down to VCC = +1.1V, immunity to short VCC transients (<40µs at 100mV overdrive), watchdog input (WDI) pulse detection as short as 150ns, and compatibility with CMOS-level MR/WDI inputs across 1.2V–5.5V VCC range.

Technical Context

This device belongs to the MAX6864–MAX6869 family, integrating voltage monitoring, manual reset assertion, and watchdog timer functionality in a single die. Its watchdog logic clears on any WDI edge (rising or falling), resets on MR assertion or VCC dropout, and triggers a full reset timeout upon expiration - ensuring robust recovery from software lockups without requiring external timing components.

The internal reset generator guarantees monotonic behavior during VCC ramp-up/down, with a fixed 1200ms timeout (D6 option) and hysteresis of 0.5% of VTH. The active-high push-pull RESET output is referenced to VCC and delivers VOH ≥ 0.8×VCC (ISOURCE = 500µA) and VOL ≤ 0.3V (ISINK = 1.2mA), supporting direct interface to µP reset inputs without pullup resistors.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount, 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 TPS3837K33DBVR and STM6315SW13F, the MAX6865UK18D6L+T uniquely combines 1.8V precision reset, 1200ms timeout, 209s watchdog, and active-high push-pull output - making it the only viable choice for low-power medical wearables requiring both voltage supervision and firmware crash recovery.

Availability

MAX6865UK18D6L+T is available at Aetrix Electronics and suitable for glucose monitors, patient monitoring devices, and smart wearables requiring stable component supply across extended production lifecycles and battery-life-critical designs.

Supply support for MAX6865UK18D6L+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, mixed-signal, and power management ICs for demanding industrial, medical, and communications applications.

The MAX6864–MAX6869 product line targets ultra-low-power microprocessor supervision in battery-operated medical and portable electronics, emphasizing nanoscale current consumption, wide VCC range, and integrated watchdog reliability.

FAQ

What is the exact reset threshold voltage of the MAX6865UK18D6L+T?

The MAX6865UK18D6L+T has a factory-trimmed reset threshold of 1.800V with ±2.5% tolerance over temperature (−40°C to +85°C). This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "18" corresponds to 1.8V nominal VTH. The device guarantees valid reset assertion down to VCC = +1.1V, independent of threshold accuracy.

Does the MAX6865UK18D6L+T support active-high or active-low reset output?

The MAX6865UK18D6L+T features an active-high push-pull RESET output (pin 1), as confirmed in the MAX6865-specific pin description on page 8 of the datasheet. It drives high (VOH ≥ 0.8×VCC) when reset is deasserted and low (VOL ≤ 0.3V) when asserted - eliminating need for external pullup resistors unlike open-drain variants.

What is the watchdog timeout period for the MAX6865UK18D6L+T?

The MAX6865UK18D6L+T uses the "L" watchdog suffix, providing a typical timeout period of 209 seconds (min 95s, max 487s) as specified in Table 3 (Watchdog Timeout). This long interval is optimized for firmware with extended idle or measurement cycles, such as in clinical-grade glucose monitors.

How does the manual reset (MR) input function on the MAX6865UK18D6L+T?

The MR input on the MAX6865UK18D6L+T is active-low with an internal 10kΩ pullup to VCC. Driving MR low initiates reset; the RESET output remains asserted for the full 1200ms timeout after MR returns high. Glitch rejection is 200ns, and minimum pulse width is 1µs - enabling reliable button-based reset without external debounce circuitry.

Is the MAX6865UK18D6L+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK18D6L+T shares the same 5-pin SOT23-5 package and pinout (VCC, WDI, MR, GND, RESET) with MAX6864, MAX6866, MAX6867, MAX6868, and MAX6869. However, it is not pin-compatible with MAX6854–MAX6863 due to differing pin functions (e.g., CT vs. WDI on pin 4), and substitution requires schematic and layout verification.