Description

The MAX31790 controls the speeds of up to six fans using six independent PWM outputs. The desired fan speeds (or PWM duty cycles) are written through the I²C interface. The outputs drive '4-wire' fans directly, or can be used to modulate the fan's power terminals using an external pass transistor.Tachometer inputs monitor fan tachometer logic outputs for precise (±1%) monitoring and control of fan RPM as well as detection of fan failure. Six pins are dedicated tachometer inputs. Any of the six PWM outputs can also be configured to serve as tachometer inputs.The PWM_START inputs select the PWM output status at startup to ensure appropriate fan drive when power is first applied.To ensure low acoustic impact of fan control, all changes in PWM duty cycle take place at a controlled, programmable rate.The MAX31790's 3.0V to 5.5V supply voltage range and I²C-compatible interface make it ideal for fan control in a wide range of cooling applications. The MAX31790 is available in a 28-pin TQFN package and operates over the -40°C to +125°C temperature range.ApplicationsNetworkingServersTelecom