Analog Devices Inc./Maxim Integrated MAX6865UK35D6S+T

Overview

MAX6865UK35D6S+T from Maxim Integrated is a nanopower microprocessor supervisory circuit in 5-pin SOT23 package, combining voltage monitoring (3.5V reset threshold), manual reset input (MR), and watchdog timer (209s typical timeout) with ultra-low 170nA supply current. It asserts active-high push-pull RESET during VCC brownout, MR assertion, or watchdog timeout, and guarantees valid reset down to VCC = +1.1V - ideal for battery-powered glucose monitors and portable medical devices.

For engineers reviewing the MAX6865UK35D6S+T datasheet, MAX6865UK35D6S+T pinout, MAX6865UK35D6S+T application, or MAX6865UK35D6S+T equivalent, key selection criteria include its 3.5V factory-trimmed reset threshold, 1200ms minimum reset timeout (D6), 209s watchdog period (S suffix), active-high push-pull output, and immunity to sub-40µs VCC transients at 100mV overdrive.

Technical Context

The MAX6865UK35D6S+T implements a dual-trigger reset architecture: one path monitors VCC against a precision 3.5V threshold (±2.5% tolerance), while a second path responds to MR low or WDI inactivity exceeding 209s (typ). Its internal watchdog timer clears on any WDI edge, MR assertion, or RESET assertion - preventing false timeouts during system recovery.

Reset assertion persists for ≥1200ms after VCC rises above 3.5V and MR deasserts, ensuring µP initialization completes before release. The device operates across -40°C to +85°C with guaranteed functionality down to VCC = 1.1V, and features 10kΩ internal MR pullup and 20nA WDI input leakage.

Key Specifications

Pinout & Package

Package: 5-pin SOT23 (lead-free, +T suffix), footprint-compatible with industry-standard 5-lead SOT-23 packages.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6864UK35D6S+T, the MAX6865UK35D6S+T's active-high RESET simplifies connection to modern low-voltage µPs; versus TPS3837K33DBVR, it delivers 10× lower supply current and critical watchdog protection for unattended operation.

Availability

MAX6865UK35D6S+T is available at Aetrix Electronics and suitable for portable medical devices, battery-powered diagnostics, and industrial sensor nodes requiring stable component supply with long-term lifecycle support.

Supply support for MAX6865UK35D6S+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 connectivity in demanding environments.

The MAX68xx family targets ultra-low-power supervisory needs in portable and medical electronics, delivering nanopower operation, factory-trimmed thresholds, and integrated watchdog functionality without external components.

FAQ

What is the exact reset threshold voltage of the MAX6865UK35D6S+T?

The MAX6865UK35D6S+T has a factory-trimmed reset threshold of 3.500V 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 "35" corresponds to 3.500V nominal. The device guarantees reset assertion when VCC falls below this threshold and remains asserted until VCC exceeds it and the 1200ms timeout elapses.

Does the MAX6865UK35D6S+T support active-high or active-low reset output?

The MAX6865UK35D6S+T provides an active-high push-pull RESET output (Pin 1), as specified in the MAX6865 pin description on page 8 of the datasheet. This eliminates the need for an external pullup resistor and directly interfaces with µPs requiring high-true reset signals - unlike the MAX6864 variant, which offers active-low output.

What is the watchdog timeout period for the MAX6865UK35D6S+T?

The MAX6865UK35D6S+T uses the "S" watchdog suffix, providing a typical timeout period of 209 seconds (min 95s, max 487s) as defined in Table 3 (Watchdog Timeout). The timer resets on any WDI edge and triggers reset if WDI remains static beyond this interval - enabling robust detection of long-duration firmware hangs.

Can the MAX6865UK35D6S+T operate reliably below 1.8V supply?

Yes, the MAX6865UK35D6S+T operates from VCC = 1.2V to 5.5V and guarantees valid RESET output down to VCC = +1.1V, as stated in the Absolute Maximum Ratings and Electrical Characteristics tables. At 1.2V, supply current remains ultra-low (190nA typ), and reset timing parameters remain within specification - making it suitable for single-cell LiFePO₄ or deeply discharged alkaline systems.

Is the MAX6865UK35D6S+T pin-compatible with other MAX68xx devices?

The MAX6865UK35D6S+T uses the standard 5-pin SOT23 package and shares identical pinout with MAX6864/MAX6866 variants (Pin 1: RESET, Pin 2: GND, Pin 3: MR, Pin 4: WDI, Pin 5: VCC). However, it is not pin-compatible with MAX6861–MAX6863 (which use CT instead of WDI) or MAX6854–MAX6856 (which lack WDI), as confirmed in the Pin Configurations section (page 15) and Selector Guide (page 16).