ST's Hard-Disk-Drive Motor Controller Chip Maximizes Battery Life

The L7208 is based on a flexible digital architecture which minimizes the Bill-of-Materials, reducing costs for manufacturers and allowing the device to be used across a broad range of HDD-based products. The IC includes two innovative technologies: ST’s respected Smooth Drive pseudo-sinusoidal digital-drive technique for minimizing acoustic noise from the spindle motor, an important feature for CE applications where quiet operation is essential; and a free-fall sensor interface.

Power consumption is extremely low in all operating modes, including a highly efficient sleep mode, to deliver extended battery life in the application. The class AB output stage has zero dead-band and minimal crossover distortion, and the power FETs can deliver up to 0.5A peak current. The voice-coil section includes a 14-bit digital-to-analog converter (DAC) for current commands and load/unload circuits.

In addition to the Smooth Drive feature, the spindle-motor section includes circuits for spindle-current limiting, start-up position sensing, and spindle braking during power down. The L7208 is register controlled, and connects to the host system through a serial bus running at up to 50MHz. Auxiliary functions integrated on the chip include an internal isolation FET, a 10-bit ADC, programmable voltage regulators, a shock sensor circuit and monitors for all voltage levels. The chip is produced using ST’s field-proven Bipolar-CMOS-DMOS (BCD) technology, which combines digital circuits, precision bipolar analog circuits and high-efficiency power FETs on the same piece of silicon.

ST’s HDD motor-controller family also includes the L7207, which is firmware compatible with the L7208 and is designed both for the 5V drives made for mobile applications such as laptop computers, and for 12V desktop computer drives.

Available in an ultra-thin LGA package, samples of the L7208 HDD Motor Controller will be available in October 2006, priced at $15.00.