Analog Devices Inc./Maxim Integrated MAX6865UK31D6L+T

Overview

The MAX6865UK31D6L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, combining voltage monitoring, manual reset input (MR), and watchdog timer (WDI) functions. It asserts an active-high push-pull RESET output when VCC drops below 3.075V (typ), MR is pulled low, or the watchdog expires after 209s (typ). Designed for ultra-low-power systems, it draws only 170nA (typ) supply current and guarantees valid reset operation down to VCC = +1.1V.

For engineers reviewing the MAX6865UK31D6L+T datasheet, MAX6865UK31D6L+T pinout, MAX6865UK31D6L+T application, or MAX6865UK31D6L+T equivalent, key selection criteria include its factory-trimmed 3.075V reset threshold, 1200ms minimum reset timeout (D6), 209s watchdog period (L suffix), active-high push-pull RESET output, and compatibility with battery-powered medical and portable electronics requiring guaranteed reset assertion at low VCC.

Technical Context

This device implements a precision bandgap-based voltage monitor with ±2.5% threshold accuracy over -40°C to +85°C, coupled with a temperature-stable RC-based watchdog timer. Its internal 10kΩ MR pullup and glitch rejection (200ns) enable robust manual reset handling without external components.

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), ensuring reliable interface with µP reset inputs across 1.2V–5.5V supply range. The watchdog clears on any WDI edge and tolerates pulse widths as short as 150ns.

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 MAX6864UK31D6L+T and TPS3837K33DBVR, the MAX6865UK31D6L+T uniquely combines active-high RESET, 209s watchdog, and nanopower operation-enabling simplified design in space- and energy-constrained medical and IoT endpoints where reset polarity and long watchdog intervals are critical.

Availability

MAX6865UK31D6L+T is available at Aetrix Electronics and suitable for portable medical devices, industrial handheld scanners, smart asset trackers, and battery-powered IoT sensors requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6865UK31D6L+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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX6854–MAX6869 family was designed specifically for ultra-low-power microprocessor supervision in battery-critical applications, integrating precision voltage monitoring, configurable reset timing, and robust watchdog functionality in minimal 5-pin SOT23 packages.

FAQ

What is the exact reset threshold voltage of the MAX6865UK31D6L+T?

The MAX6865UK31D6L+T has a factory-trimmed reset threshold voltage of 3.075V (typical), with tolerance of ±2.5% over -40°C to +85°C. This value corresponds to the "31" suffix in the part number per Maxim's Threshold Suffix Guide, and is optimized for reliable brownout detection in 3.3V systems where VCC may dip near 3.0V during transient load conditions. The MAX6865UK31D6L+T guarantees reset assertion down to VCC = +1.1V regardless of threshold drift.

Does the MAX6865UK31D6L+T require external components for basic operation?

No, the MAX6865UK31D6L+T operates autonomously with no external components required. It integrates an internal 10kΩ pullup on the MR pin, precision voltage reference, RC-based watchdog timer, and push-pull RESET driver. Only a 0.1µF ceramic bypass capacitor from VCC to GND is recommended for noise immunity-this is standard practice, not a functional requirement. The MAX6865UK31D6L+T eliminates discrete resistors, capacitors, or diodes typically needed in discrete reset solutions.

How does the watchdog timer in the MAX6865UK31D6L+T function, and what is its timeout period?

The MAX6865UK31D6L+T watchdog timer monitors the WDI pin and triggers a reset if no edge (rising or falling) occurs within 209 seconds (typical), as specified by the "L" suffix. The timer clears on every WDI transition and remains disabled while RESET is asserted. It accepts pulses as short as 150ns, enabling minimal firmware overhead. Unlike windowed watchdogs, this is a simple timeout timer-ideal for periodic sanity checks in low-duty-cycle applications like smart sensors. The MAX6865UK31D6L+T does not support programmable or adjustable watchdog periods.

What is the purpose of the D6 suffix in MAX6865UK31D6L+T, and how does it affect reset behavior?

The "D6" suffix in MAX6865UK31D6L+T specifies a minimum reset timeout period of 600ms, with typical and maximum values of 900ms and 1200ms respectively. After VCC rises above 3.075V or MR is released, the active-high RESET output remains asserted for this full duration to ensure the microprocessor completes power-up initialization and clock stabilization. This extended hold time is critical for µPs with slow internal oscillators or complex boot sequences. The MAX6865UK31D6L+T uses internal RC timing-no external capacitor is needed to set this interval.

Is the MAX6865UK31D6L+T pin-compatible with other devices in the MAX68xx family?

The MAX6865UK31D6L+T shares the same 5-pin SOT23-5 package and pinout as all MAX6864–MAX6869 variants (pins: 1=RESET, 2=GND, 3=MR, 4=WDI, 5=VCC), making it mechanically and electrically pin-compatible within that subgroup. However, it is not pin-compatible with MAX6861–MAX6863 (which use CT instead of WDI on pin 4) or MAX6854–MAX6856 (which lack WDI entirely). The MAX6865UK31D6L+T's active-high RESET output also differs from the active-low versions (e.g., MAX6864), so signal polarity must be verified in the target system.