The MAX6620 controls the speeds of up to four fans using four independent linear voltage outputs. The drive voltages for the fans are controlled directly over the I²C interface. Each output drives the base of an external bipolar transistor or the gate of a FET in high-side drive configuration. Voltage feedback at the fan's power-supply terminal is used to force the correct output voltage.The MAX6620 offers two methods for fan control. In RPM mode, the MAX6620 monitors four fan tachometer logic outputs for precise (±1%) control of fan RPM and detection of fan failure. In DAC mode, each fan is driven with a voltage resolution of 9 bits and the tachometer outputs of the fans are monitored for failure.The DAC_START input selects the fan power-supply voltage at startup to ensure appropriate fan drive when power is first applied. A watchdog feature turns the fans fully on to protect the system if there are no valid I²C communications within a preset timeout period.The MAX6620 operates from a 3.0V to 5.5V power supply with low 250µA supply current, and the I²C-compatible interface makes it ideal for fan control in a wide range of cooling applications. The MAX6620 is available in a 28-pin TQFN package and operates over the -40°C to +125°C automotive temperature range.ApplicationsCommunications EquipmentConsumer ProductsServersStorage Equipment