Variable speed control for single-phase motors

If you need to provide flexible variable speed control for single-phase brushless DC fans and blowers, then the ZXBM1004 pre-driver IC from Zetex might be the answer.

Fully compatible with NTC thermistor, voltage and PWM input signals, the QSOP16 packaged device provides thermal control of single-phase motors up to 100W in PC, mainframe and other applications dependent on forced air-cooling.

The ZXBM1004’s adjustable minimum speed setting prevents the fan from running too slowly or not being able to start. An external resistor protects the speed control circuit against supply voltage fluctuations, ensuring air flow is maintained at the target level. A built-in automatic restart function is set using a single capacitor.

An integral Hall amplifier enables Hall sensors to be wired directly to the controller for the detection of fan rotation and speed. Compatible with virtually any type of Hall-effect sensor, the ZXBM1004 removes the need for external signal conditioning circuitry.

Two separate diagnostic outputs are offered by the controller – a pulsed rotor speed output and a locked rotor alarm output. In response to a locked rotor condition, the device puts phase drive outputs into a safe mode that protects the transistor pair and motor windings.

The price of the ZXBM1004 through distributors is $0.88 in quantities of 1000.

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