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Spindle Motor Brake Circuit

IP.com Disclosure Number: IPCOM000109882D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Enami, K: AUTHOR

Abstract

Disclosed is a circuit which makes a spindle motor stop quickly. Many hard disk files have brake means to reduce disk surface damage by contact start/stop. This circuit includes no mechanical parts like a relay and works when the power supply is cut off. Also, it can be used with brush-less spindle motor driver IC that can supply large current to spindle motor coils directly.

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Spindle Motor Brake Circuit

       Disclosed is a circuit which makes a spindle motor stop
quickly.  Many hard disk files have brake means to reduce disk
surface damage by contact start/stop.  This circuit includes no
mechanical parts like a relay and works when the power supply is cut
off.  Also, it can be used with brush-less spindle motor driver IC
that can supply large current to spindle motor coils directly.

      The drawing shows this circuit.  In the circuit, the spindle
motor driver consists of one IC module, and it has a port for start/
stop mode change.  When this port is set in the stop mode, the IC
keeps ports for motor coils U, V, and W at high impedance.

      When the power supply is cut off or the start/stop port is set
in stop mode, Q3 turns off.  Then, the voltage of C1 turns Q1 and Q2
on.  Therefore, the current which is generated by electromotive force
of the spindle motor coil V and W causes brake torque.  Motor coil U
is used for the power source both of brake torque and voice coil
motor control.  When the voltage of U is lower than the one of V +
W, brake current flows through diode D2 and Q1 or Q2.  When it is
higher, the current generated by the electromotive force of U makes
the magnetic head go to home position.

      In this operation, the voltage of the ports for motor coil U,
V, W is not forced to be lower than ground level.  It can avoid
spindle motor driver IC damage by unexpected large current caused by
the pa...