| 摘要 |
A HDD write driver circuit (30) having two sets of boost devices (Q1, M2, and Q2, M1) which are temporarily turned on during a current reversal to boost the normal current and increase the differential transient voltage across the coil (LS) while decreasing the TRTF. During a current reversal cycle, one set of transistors is turned on while the other set is left off. The on set to pulls the node at one end of the coil substantially to the positive rail, and pulls the other node at the other end of the coil substantially to the lower rail (Vee). The boost FETs (M1, M2) are preferably large PMOS devices that must be driven hard to achieve a quick transient switching time. Advantageously, when one of the PMOS FETs (M1, M2) are on, the associated series resistor (RS) is bypassed. The voltage at nodes HX and HY are no longer limited by an IR voltage drop associated with a resister (RS) therefore increasing the differential transient voltage across nodes HX and HY by increasing the maximum transient voltage of the pull-up node. Preferably, each node (HX, HY) of the coil (LS) can be pulled to within 0.2 volts of the positive rail.
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