Fan Control and Monitoring
Control up to 6 fans with 9-bit PWM Drive, Customizable PWM Dutycycle Rate-of-change, and PWM Frequencies from 25Hz to 25kHz
Up to 12, 11-bit Tachometer Inputs for speed and failure detection
Automatic Fan Speed Control Loops, RPM control on fans with digital tachometer outputs
High System Reliability
Fan failure/fault detection with automatic safe state responses.
Power-up defaults are hardware selectable. Default PWM frequency, duty cycle, and start-up speed can be set by external pin connections.
Integrated Watchdog Timer
I2C Communication interface
Fast-mode I2C controller up to 400kbps
Open-drain pins
16 possible hardware-selectable addresses
Operating characteristics
Wide supply voltage range: 1.62V to 3.6V
Extended temperature: –40°C up to 125°C
Clock system
Internal 32kHz oscillator with ±5% accuracy
External 32kHz crystal oscillator (LFXT)
32.768kHz Digital clock output
Package
Bom-to-BOM and Pin-to-pin with common fan controllers
28 pin LGA 4x4mm (Identical footprint to WQFN 4x4mm)
RoHS Compliant
The FAN31790 is an intelligent fan controller that can control the speed of six fans using independent PWM outputs and dedicated TACH inputs. The device is designed for 4-wire fans but can still be used to modulate the speed of 3-wire and 2-wire fans via external power transistors. The device can monitor the speed of up to 12 fans with six dedicated tachometer inputs and any of the PWM output channels can be reconfigured as additional tachometers. Using a tachometer allows the device to automatically adjust the PWM duty cycles to maintain desired fan speeds. Target fan speeds and update rates can be configured via an I2C interface.
This device’s default power-up states are hardware configurable with external connections. The fan spin-up behavior, PWM frequency, PWM duty cycle, and the integrated watchdog timer can all be configured via pin configurations. This allows customization of fan behavior before custom settings are loaded via the I2C bus.
The FAN31790 supports a 1.62-3.6V supply voltage for PWM/TACH pins and the I2C interface. The FAN31790 is designed to be pin-to-pin and BOM-to-BOM compatible with common fan controllers and it offers a matching I2C interface and register map to leverage any pre-existing software drivers.
| Top documentation | Type | Title | Format options | Date |
|---|---|---|---|---|
| * | Data sheet | FAN31790 6-Channel PWM/RPM Fan Controller datasheet | PDF | HTML | 29 Apr 2026 |
| Application brief | Migration Guide to FAN31790 from MAX31790 | PDF | HTML | 28 Apr 2026 |
For additional terms or required resources, click any title below to view the detail page where available.
| Package | Pins | CAD symbols, footprints & 3D models |
|---|---|---|
| LGA (ZFP) | 28 | Ultra Librarian |
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