Analog Devices Inc./Maxim Integrated MAX6865UK22D4L+T

Overview

The MAX6865UK22D4L+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 2.235V reset threshold (suffix "22"), 1200ms minimum reset timeout (suffix "D4"), and 209s typical watchdog timeout (suffix "L"). It monitors VCC, responds to manual reset (MR) assertion, and triggers reset upon watchdog timer expiration - designed for battery-critical portable medical and handheld devices.

For engineers reviewing the MAX6865UK22D4L+T datasheet, MAX6865UK22D4L+T pinout, MAX6865UK22D4L+T application, or MAX6865UK22D4L+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-voltage systems requiring long watchdog intervals.

Technical Context

The MAX6865UK22D4L+T implements a dual-monitoring architecture: a precision voltage detector with ±2.5% threshold accuracy over –40°C to +85°C, and an independent watchdog timer that clears on any WDI edge (rising or falling) and expires after 209s (typ). Its internal 10kΩ MR pullup enables direct switch interfacing without external components.

Reset assertion is latched and held for the full 1200ms timeout after VCC rises above 2.235V *and* MR deasserts *and* watchdog timer resets - ensuring reliable µP initialization even during marginal power recovery. The push-pull active-high RESET output sources up to 500µA at VCC ≥ 2.38V while maintaining VOH ≥ 0.8×VCC.

Key Specifications

Pinout & Package

Package: 5-pin SOT23-5, lead-free, surface-mount. Pin 1 is marked with dot; pin numbering follows standard SOT23 convention (counterclockwise from mark).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6865UK22D4L+T, MAX6864UK22D4L+T offers identical supervision timing but requires µP-level reset inversion, while TPS3837K22DBVR reduces cost and complexity at the expense of runtime fault detection capability.

Availability

MAX6865UK22D4L+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered industrial scanners, and low-power wireless sensor nodes requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6865UK22D4L+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 in industrial, medical, and communications markets.

The MAX68xx family delivers nanopower supervisory functions specifically for space- and energy-constrained portable electronics, emphasizing ultra-low ICC, wide VCC range, and integrated watchdog reliability.

FAQ

What is the exact reset threshold voltage of the MAX6865UK22D4L+T?

The MAX6865UK22D4L+T has a factory-trimmed reset threshold of 2.235V, with guaranteed tolerance of ±2.5% over –40°C to +85°C (min 2.180V, max 2.290V). This value is encoded in the "22" suffix per Maxim's Threshold Suffix Guide (Table 2), and applies to the VCC monitor input. The MAX6865UK22D4L+T asserts RESET when VCC falls below this threshold and holds it for 1200ms after VCC recovers.

Does the MAX6865UK22D4L+T require external components for basic operation?

No, the MAX6865UK22D4L+T operates autonomously with zero external components: its MR input includes a 10kΩ internal pullup to VCC, the watchdog timer uses an on-chip oscillator, and the voltage reference is trimmed during manufacturing. Only a 0.1µF ceramic bypass capacitor on VCC is recommended for noise immunity - not strictly required but strongly advised for robust performance in real-world PCB layouts.

How does the watchdog timer in the MAX6865UK22D4L+T clear and expire?

The MAX6865UK22D4L+T watchdog timer clears on any rising or falling edge at the WDI pin and expires after 209s (typical), with min 95s and max 487s variation. It does not run while RESET is asserted. If WDI remains static (high or low) beyond the timeout, RESET activates for 1200ms. The MAX6865UK22D4L+T detects pulses as short as 150ns, making it resilient to EMI-induced false toggles.

What is the function of Pin 1 on the MAX6865UK22D4L+T?

Pin 1 of the MAX6865UK22D4L+T is the RESET output, configured as push-pull active-high. When asserted (during VCC brownout, MR activation, or watchdog timeout), it drives high to VCC; when deasserted, it pulls low to GND. This eliminates the need for an external pullup resistor and provides rail-to-rail logic compatibility with the host µP's VCC domain - a key differentiator from open-drain alternatives.

Can the MAX6865UK22D4L+T operate reliably at VCC = 1.2V?

Yes, the MAX6865UK22D4L+T is fully specified from VCC = 1.2V to 5.5V. Its reset output remains valid down to VCC = +1.1V, and supply current is characterized at 1.2V (190nA typ). At 1.2V, the device guarantees RESET assertion when VCC falls below 2.235V (via resistive divider), maintains MR glitch rejection, and sustains watchdog timing accuracy - enabling use with single-cell NiMH or low-VCC LDOs.