Read/write circuit with switchable head resistance for read and write modes

摘要

A read/write circuit for a disk drive system with a two- terminal magnetic head, having an adjustable damping resistor across the magnetic head. A switch network connects across the magnetic head and controls a resistor network to obtain an optimum level of impedance across the magnetic head in both the read mode and the write mode. The circuit provides a lower and well-defined impedance across the magnetic head in the write mode for all operating voltages across the head. A clamp circuit operates to prevent the write current source from saturating to improve current switching speed in the write mode.