Enhanced voltage drive circuit for HDD write driver
US6373298B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 30, 2001 |
| Grant date | Apr 16, 2002 |
| Priority date | — |
| Expiry date | Jan 30, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/567
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.