1℃のリモート温度センサ付ファンスピードレギュレータによる自動閉ループファン制御及びPWMノイズの除去
SUNNYVALE, CA-February 19, 2002-Maxim Integrated Products introduces the MAX6661 remote temperature sensor and intelligent closed-loop fan controller. Fan speed is voltage controlled, as opposed to PWM controlled, greatly reducing acoustic noise and maximizing fan reliability. An on-chip power device drives 5V and 12V fans rated up to 250mA.
Housed in a small 16-pin QSOP package, the MAX6661 measures the temperature of a common-collector PNP, such as a substrate PNP of a microprocessor or a diode-connected transistor. It then uses the resulting temperature data to regulate the fan’s speed, freeing up the processor from fan control functions.
The closed-loop fan controller regulates fan speed with tachometer feedback from the fan and adjusts fan speed based on the remote-junction temperature. If desired, the automatic temperature-based fan-speed control function can be bypassed and the fan can be placed under direct, open-loop control.
Temperature data is updated continuously at a user-programmable rate and is readable at any time over the SPI-compatible interface. The MAX6661 is accurate to 1°C (max) when the remote junction is between +60°C and +100°C and 3°C accurate (max) when the remote junction is between +25°C and +125°C. Data is formatted as an 11-bit word with 0.125°C resolution.
When a temperature or voltage measurement falls outside the user-programmed high- and low-limit thresholds, the MAX6661 generates a latched interrupt output at the ALERT-bar pin. In addition, the OVERT-bar comparator output asserts when the temperature exceeds an additional programmed high limit and deasserts only when the temperature falls below the programmed low limit. This pin can be used to facilitate a system shutdown.
The MAX6661 communicates through a 3-wire serial interface accepting standard SPI protocol. This interface is used to program the MAX6661’s configuration, including all temperature alarm thresholds and the fan trip threshold and gain settings. It is also used to set fan speed directly in open-loop mode.
The MAX6661 operates with a supply voltage between 3.0V and 5.5V. Average supply current is 450µA (typ) and standby current is just 3µA (typ).
Prices start at $3.39 for the MAX6661 (1000-up, FOB USA).
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