The MAX6661 is a remote temperature sensor and fan-speed regulator that provides complete closed-loop fan control. It integrates thermal measurement and fan regulation, which can be programmed by the user over the SPI bus. The device enables automatic fan control that is proportional to the remote junction temperature, and the temperature feedback loop can be broken at any time for system control over the fan speed. Fan speed is voltage controlled, reducing acoustic noise and maximizing fan reliability. Temperature data is updated every 500ms and can be read over the SPI interface. The MAX6661 is accurate to 1°C (max) when the remote junction is between +60°C to +100°C. Data is formatted as a 10-bit + sign word with 0.125°C resolution. The MAX6661 is specified between -40°C to +125°C and is available in a 16-pin QSOP package.
The MAX6661 is a remote temperature sensor and fan‑speed regulator that provides closed‑loop fan control via an SPI‑compatible serial interface. It converts the temperature of a remote PN‑junction to a 10‑bit signed digital word with 0.125 °C resolution and updates the data every 500 ms. The device includes an on‑chip power driver capable of driving fans up to 250 mA and offers programmable temperature thresholds and gain settings.
The datasheet specifies electrical characteristics, absolute maximum ratings, pin descriptions, and recommended PCB layout practices. It also describes the SPI command protocol, register map, and standby mode operation, enabling designers to integrate the MAX6661 into telecom, server, workstation, and electronic instrument applications.
| Supply Voltage Range (VCC) | 3.0 V – 5.5 V |
|---|---|
| Fan Supply Voltage (V_FAN) | 4.5 V – 13.5 V |
| Operating Temperature Range | -40 °C to +125 °C |
| Fan Output Current | 250 mA |
| Temperature Accuracy (60 °C–100 °C) | ±1 °C (max) |
| Standby Supply Current | <10 µA (typ) |
The fan supply voltage (V_FAN) can be between 4.5 V and 13.5 V.
The on‑chip power device can drive fans rated up to 250 mA.
The MAX6661 operates from –40 °C to +125 °C.