Analog Devices Inc./Maxim Integrated MAX6865UK42D3S+T

Overview

The MAX6865UK42D3S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in a 5-pin SOT23 package, featuring ultra-low 170nA typical supply current, factory-trimmed 4.200V reset threshold (±2.5%), 300ms minimum reset timeout, and integrated watchdog timer with 3.3s typical timeout. It monitors VCC, responds to manual reset (MR), and asserts active-high push-pull RESET during brownout, power-up, or watchdog expiration - used in battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK42D3S+T datasheet, MAX6865UK42D3S+T pinout, MAX6865UK42D3S+T application, or MAX6865UK42D3S+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = +1.1V, immunity to sub-40µs VCC transients, MR glitch rejection of 200ns, and compatibility with 1.2V–5.5V supply rails in space-constrained portable systems.

Technical Context

The MAX6865UK42D3S+T implements a voltage-monitoring comparator with 2.5% hysteresis, a digital watchdog timer that clears on any WDI edge (min pulse width 150ns), and a fixed 300ms reset timeout after VCC recovery or MR deassertion. Its internal 10kΩ MR pullup and push-pull RESET output eliminate external components for most implementations.

This device belongs to the MAX6864–MAX6869 series with S-suffix watchdog (3.3s typ), D3 reset timeout (150–300ms), and 42-threshold suffix (4.200V). It operates across –40°C to +85°C and guarantees valid reset assertion even as VCC falls to 1.1V - critical for low-voltage brownout detection in medical wearables.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SOT-23 layouts. Thermal resistance θ_JA = 140°C/W; max continuous power dissipation = 571mW at +70°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3836K33DBVR and STM6315SW33DX, the MAX6865UK42D3S+T delivers 10x lower supply current, integrated watchdog with edge-triggered clear, and guaranteed reset validity down to 1.1V - making it uniquely suited for long-life, safety-critical medical wearables requiring autonomous fault recovery.

Availability

MAX6865UK42D3S+T is available at Aetrix Electronics and suitable for glucose monitors, patient vital sign recorders, handheld diagnostics, and low-power wearable sensors requiring stable component supply across extended production lifecycles.

Supply support for MAX6865UK42D3S+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 family was engineered specifically for ultra-low-power, high-reliability supervisory functions in battery-operated medical and portable electronics - emphasizing nanoscale ICC, wide VCC range, and robust noise immunity.

FAQ

What is the exact reset threshold voltage of the MAX6865UK42D3S+T?

The MAX6865UK42D3S+T has a factory-trimmed reset threshold of 4.200V with ±2.5% tolerance over –40°C to +85°C. This value is confirmed in Table 2 (Threshold Suffix Guide) of the datasheet, where suffix "42" corresponds to nominal 4.200V. The device guarantees valid reset assertion down to VCC = +1.1V, independent of threshold accuracy.

Does the MAX6865UK42D3S+T require external components for basic operation?

No, the MAX6865UK42D3S+T requires no external components for core supervision. Its internal 10kΩ MR pullup, precision voltage reference, and fixed-timing architecture eliminate need for external resistors, capacitors, or diodes. Only a 0.1µF ceramic bypass capacitor on VCC is recommended for noise suppression - standard practice for all ICs.

How does the watchdog timer in the MAX6865UK42D3S+T clear and timeout?

The MAX6865UK42D3S+T watchdog timer clears on any rising or falling edge at WDI (min pulse width 150ns) and times out after 3.3s (typical, S-suffix). Timeout triggers active-high RESET for 300ms (D3). The timer halts while RESET is asserted and resumes counting immediately upon deassertion - enabling precise software-controlled reset windows without hardware complexity.

What is the meaning of "D3S" in the MAX6865UK42D3S+T part number?

In MAX6865UK42D3S+T, "D3" specifies the reset timeout option (150–300ms min/typ), and "S" denotes the watchdog timeout variant (3.3s typical). These suffixes follow Maxim's ordering convention: UK = base prefix, 42 = 4.200V threshold, D3 = timeout code per Table 4, S = watchdog code per Table 3 - fully documented in the Ordering Information section.

Is the MAX6865UK42D3S+T pin-compatible with other supervisory ICs?

The MAX6865UK42D3S+T uses a standard 5-pin SOT23 package with pin 1 = RESET (active-high push-pull), pin 2 = GND, pin 3 = MR, pin 4 = WDI, pin 5 = VCC. It is not pin-compatible with MAX6854/MAX6855 series (no WDI) or MAX6861–MAX6863 (CT instead of WDI), but shares footprint with MAX6864/MAX6866 variants - enabling direct substitution within the same family.