ASYMMETRICAL DRIVER

摘要

A drive circuit having asymmetrical drivers. In an embodiment, a brushless DC motor may be driven by a drive circuit having three high-side MOSFETs and three low-side MOSFETs. A driver controller turns the MOSFETs on and off according to a drive algorithm such that phase currents are injected into motor coils to be driven. The high-side MOSFETs may be sized differently than the low-side MOSFETs. As such, when a MacDonald waveform (or similar drive algorithm) is used to drive the phases of the motor, less power may be required during disk spin-up because the MOSFETs that are on more (e.g., the low-side MOSFETs with a MacDonald waveform) may be sized larger than the MOSFETs that are on less (e.g., the high-side MOSFETs). In this manner, less power is dissipated in the larger size MOSFETs that are on more than the others.

主权项

1. A drive circuit, comprising:
a bridge circuit including a first drive circuit and a second drive circuit, the first drive circuit having a first value of a drive characteristic and the second drive circuit having a second value of the drive characteristic that is greater than the first value, each drive characteristic being a parameter indicating a power dissipation of the corresponding drive circuit where the larger the value of the drive characteristic the larger the power dissipation of the corresponding drive circuit; and wherein the first and second drive circuits are driven by an asymmetrical drive algorithm to control the first and second drive characteristics during a phase drive cycle to activate the first drive circuit for a longer portion of the drive cycle than the second drive circuit.