Method and circuit for determining the velocity of a data detector mechanism of a mass storage device, or the like, using a BEMF voltage in the associated voice coil
AssigneeSTMicroelectronics S.r.l.
InventorsFrancesco Carobolante, Paolo Menegoli
Life of this patent
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Abstract
A circuit and method for measuring a back EMF voltage of a voice coil in a mass storage device, or the like, includes an amplifier connected across the coil to produce an output signal proportional to a voltage across the coil and a circuit connected to selectively connect the output signal of the amplifier to a circuit output when a driving current is not applied to said coil. A sample window is generated after drive currents within the coil have been allowed to decay to zero, and between a time during which a PWM signal changes from negative to positive and a time when the PWM waveform crosses a voltage error value.
Claims15
A circuit for measuring a back EMF voltage of a coil in PWM operation, comprising:
- an amplifier connected across the coil to produce an output signal proportional to a voltage across the coil;
- and
- a circuit connected to selectively connect the output signal of the amplifier to a circuit output when a driving current is not applied to said coil.
A circuit for determining a BEMF voltage of a coil, comprising:
- an amplifier connected across said coil;
- a switch operable to selectively connect an output of the amplifier to a circuit output;
- a circuit for operating said switch to connect the output of the amplifier to the circuit output at a time during which no drive current is being applied to said coil.
A method for determining a BEMF voltage of a coil, comprising:
- driving the coil with a drive current for a time proportional to an error signal in the loop;
- discontinuing the drive current;
- allowing any current in the coil to decay to approximately zero;
- and
- measuring the voltage across the coil while the current in the coil is approximately zero, whereby the measured voltage corresponds to the BEMF voltage of the coil.
Dependencies are inferred from the claim text.