A latch apparatus is configured to latch an actuator arm assembly that can
position a read/write head relative to a data storage disk in a disk
drive. The latch apparatus includes a latch arm, a coil, a permanent
magnet, and a latch control circuit. The latch arm is configured to be
moved between a closed position that inhibits movement of the actuator
arm assembly in a landing zone and an open position that does not inhibit
movement of the actuator arm assembly in the landing zone. The coil is
configured to generate an electromagnetic force on the latch arm
responsive to a coil current. The permanent magnet is configured to
generate a magnetic force on the latch arm that is substantially opposed
to the electromagnetic force from the coil. The latch control circuit is
configured to increase according to defined open current profiles over a
defined opening time period the coil current to at least an upper defined
level to cause the coil to move the latch arm from the closed position to
the open position. The latch control circuit is further configured to
decrease according to defined close current profiles over a defined
closing time period the coil current to no more than a lower defined
level to cause the permanent magnet to move the latch arm from the open
position to the closed position.