Analog Devices Inc./Maxim Integrated MAX6665ASA40

Overview

MAX6665ASA40 from Maxim Integrated is a factory-programmed thermal fan controller with integrated 250mA low-side power switch, +40°C activation threshold (±3°C max error), 1°C/4°C/8°C pin-selectable hysteresis, and dual overtemperature warning outputs (WARN at +15°C, OT at +30°C above threshold). It drives cooling fans rated up to 24V/250mA in notebook computers and server power supplies.

For engineers reviewing the MAX6665ASA40 datasheet, MAX6665ASA40 pinout, MAX6665ASA40 application, or MAX6665ASA40 equivalent, key selection criteria include its fixed +40°C trip point, SO-EP package thermal performance, FANOUT low-side drive capability, and open-drain WARN/OT signaling for system-level thermal shutdown coordination.

Technical Context

The MAX6665ASA40 integrates a precision bandgap temperature sensor, comparator with hysteresis control via HYST pin, and a low-R_DS(ON) N-channel MOSFET driver for direct fan switching. Its die temperature sensing directly controls FANOUT without external thermistors or ADCs.

FANON provides push-pull fan-status feedback, while WARN and OT deliver active-low, open-drain signals referenced to the same factory-set threshold-enabling staged thermal response: fan activation → warning → forced shutdown. Self-heating effects (up to +7.65°C at 250mA) are quantified and design-critical for hysteresis calibration.

Key Specifications

Pinout & Package

MAX6665ASA40 is housed in an 8-pin SOIC with exposed paddle (SO-EP), optimized for thermal dissipation and PCB ground-plane integration. The exposed paddle is internally connected to GND and must be soldered to the board's ground plane.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar thermal fan control applications.

Compared with LM75BIMM-3/NOPB and MAX6642AESA+, the MAX6665ASA40 delivers complete analog thermal control in a single chip - eliminating firmware dependencies, reducing component count, and guaranteeing deterministic response timing for safety-critical fan activation and shutdown.

Availability

MAX6665ASA40 is available at Aetrix Electronics and suitable for notebook computers, server power supplies, and laboratory instruments requiring stable component supply, guaranteed +40°C thermal trip accuracy, and long-term obsolescence management.

Supply support for MAX6665ASA40 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, computing, and communications applications.

The MAX6665 family was engineered specifically for autonomous, low-component-count thermal management in space- and power-constrained systems - delivering factory-trimmed accuracy without software or external sensing elements.

FAQ

What is the exact factory-programmed temperature threshold for MAX6665ASA40?

The MAX6665ASA40 has a fixed, non-adjustable fan activation threshold of +40°C, programmed at wafer test. Its accuracy is specified as ±1°C typical and ±3°C maximum over the full operating range (-40°C to +125°C), with hysteresis selectable via the HYST pin.

Can MAX6665ASA40 drive a 24V fan directly?

Yes, the MAX6665ASA40's FANOUT pin supports up to 24V fan supply voltage and can sink 250mA continuously. The internal MOSFET's R_DS(ON) ensures <0.6V saturation voltage at 250mA, minimizing self-heating and enabling efficient high-voltage fan control without external components.

How does the HYST pin affect hysteresis in MAX6665ASA40?

The HYST pin configures hysteresis in three states: unconnected = 1°C, tied to GND = 4°C, tied to VDD = 8°C. This setting determines the temperature drop required after fan activation before FANOUT turns off - critical for preventing oscillation and managing acoustic noise in sensitive environments.

What is the function of the FANON pin on MAX6665ASA40?

FANON is an active-high, push-pull logic output that goes high whenever the FANOUT switch is conducting - whether due to die temperature exceeding +40°C or FORCEON being driven low. It provides real-time fan status feedback for LEDs, system logs, or host MCU monitoring without requiring external sensing.

Are WARN and OT outputs open-drain on MAX6665ASA40?

Yes, both WARN and OT pins are active-low, open-drain outputs requiring external pull-up resistors. WARN asserts at +15°C above the +40°C threshold (+55°C total), and OT asserts at +30°C above (+70°C total), enabling independent handling of warning and emergency shutdown signals in the system.