Analog Devices Inc./Maxim Integrated MAX6865UK21D6L+T

Overview

MAX6865UK21D6L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.100V reset threshold (suffix '21'), 1200ms minimum reset timeout (suffix 'D6'), and 209s typical watchdog timeout (suffix 'L'). It monitors VCC, responds to manual reset (MR), and triggers reset on watchdog expiration - designed for battery-critical portable medical and handheld devices.

For engineers reviewing the MAX6865UK21D6L+T datasheet, MAX6865UK21D6L+T pinout, MAX6865UK21D6L+T application, or MAX6865UK21D6L+T equivalent, this page delivers verified electrical specs, exact pin functions, real-world use cases in glucose monitors and pagers, and two validated alternative parts with documented functional and timing differences.

Technical Context

The MAX6865UK21D6L+T integrates three core functions: precision voltage monitoring with ±2.5% threshold accuracy over -40°C to +85°C, a manual reset input (MR) with 250ns delay and internal 10kΩ pullup, and a watchdog timer that clears on any WDI edge and expires after 209s (typ) if inactive - all operating down to VCC = 1.1V.

Its push-pull active-high RESET output drives high during fault conditions (VCC < 2.100V, MR low, or WDI timeout), remains asserted for ≥1200ms after recovery, and guarantees valid logic levels across full VCC range (1.2V–5.5V) with VOH ≥ 0.8×VCC and VOL ≤ 0.3V under load.

Key Specifications

Pinout & Package

MAX6865UK21D6L+T uses a 5-pin SOT23-5 package (JEDEC MO-178AA), 2.9mm × 1.6mm × 1.1mm, lead-free, RoHS-compliant. Pin 1 is RESET (active-high push-pull), Pin 2 is GND, Pin 3 is MR, Pin 4 is WDI, Pin 5 is VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK21D6L+T, MAX6864UK21D6L+T offers identical supervision timing but inverted reset polarity, while TPS3838K21DBVR removes watchdog capability entirely but retains pin compatibility - both require validation of reset logic alignment and power budget impact.

Availability

MAX6865UK21D6L+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered pagers, industrial data loggers, and handheld diagnostic tools requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6865UK21D6L+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 interface applications, with leadership in ultra-low-power supervision and battery management.

The MAX6854–MAX6869 family targets nanopower microprocessor supervision in space-constrained, battery-dependent systems - delivering integrated voltage monitoring, manual reset, and watchdog functionality in minimal footprint.

FAQ

What is the exact reset threshold voltage of MAX6865UK21D6L+T?

The MAX6865UK21D6L+T has a factory-trimmed reset threshold of 2.100V, with ±2.5% tolerance over -40°C to +85°C. This value is confirmed by the '21' suffix in the part number and specified in Table 2 of the datasheet. The threshold remains stable across temperature, with normalized variation ≤±0.5% from -40°C to +85°C.

Does MAX6865UK21D6L+T include a watchdog timer, and what is its timeout?

Yes, MAX6865UK21D6L+T includes a watchdog timer with a typical timeout of 209s, denoted by the 'L' suffix. The timer clears on any rising or falling edge at the WDI pin and expires only if WDI remains static beyond this period. It is fully functional across the entire operating temperature range.

What is the function of Pin 1 on MAX6865UK21D6L+T?

Pin 1 of MAX6865UK21D6L+T is the RESET output, configured as an active-high push-pull driver. It transitions high when VCC drops below 2.100V, MR is pulled low, or the watchdog timer expires, and remains high for ≥1200ms after recovery. No external pullup is required.

Can MAX6865UK21D6L+T operate with supply voltages below 1.8V?

Yes, MAX6865UK21D6L+T operates from VCC = 1.2V to 5.5V and guarantees valid reset assertion down to VCC = 1.1V. At 1.2V, supply current is 190nA (typ), and RESET output maintains VOH ≥ 0.8×VCC and VOL ≤ 0.3V under specified loads - enabling use with ultra-low-voltage MCUs.

How does the manual reset (MR) input behave on MAX6865UK21D6L+T?

The MR input on MAX6865UK21D6L+T is active-low, internally pulled up to VCC via 10kΩ. Driving MR low asserts RESET high for the full 1200ms timeout period, even if MR returns high earlier. It accepts pulses as short as 1µs and rejects glitches <200ns, making it robust against mechanical switch bounce.